texts: How can we balance one-half of an oxygen molecule, or any other diatomic, in a chemical reaction?

texts: How can we balance oxygen or any other diatomic molecule with a fractional coefficient in a reaction?  I mean, if we can balance oxygen atoms in an odd number what happens to other oxygen atom, and can this sort of reaction even happen?


texts:
I was reading a book called 'Hundred and Seven Stories of Chemistry'.

There is a chapter about how the attributes of different elements can change in presence of enormous pressure and temperature. The book says in presence of enormous pressure and temperature potassium's 19th electron can enter the 3d orbital. Then, it would no longer be a metal.

Is it possible? If yes, is there any theoretical calculation possible for the pressure and temperature needed for this exotic behaviour?


texts: Deformation of the nematic phase of liquid crystals surviving in the solid state

texts:
Does anyone know if I were to cool a liquid crystal with a deformed nematic phase quickly, if it will preserve the deformation in the crystal lattice?

I didn't find any information in classical books on liquid crystals.


texts:
This popped into my my mind while watching a match burn (don't ask me what I was doing with a burning match...).

Now as I know it, 'ash' is what you call the residual, grey-black powdery material left over following the combustion of wood.

I'm under the impression that ash is largely just carbon, with little or no organic constituents present along with it (since I'm pretty sure that pure powdered carbon is black, not grey-black).

Now I heated what remained of the matchstick with, well...another matchstick and found out, unsurprisingly, that the ash underwent practically no visible change. So I scooped up some ash into a crevice in a concrete block and then blow-torched it for about 2 minutes. Same result. However, while I was heating it this time, it glowed orange, it subsided as soon as I turned off the torch.

Thinking about it, if I did heat it strong enough it should decompose completely to black colored elemental carbon. If that is the case, to what temperature should you heat it?

I don't think I've considered everything there is to consider in this situation, which is why I've adopted a tentative tone while typing out this question.

Could there be other, side-reactions/effects as well? What would they be?

Additionally if anyone happens to know; what is it that contributes to the grey color that ash normally assumes?


texts: why are halogens considered deactivating groups while methoxyl groups are activating?

texts:
Something's wrong with how I think of this:

methoxyl has the partial negative charge on oxygen which means it's activating. However, halogens are more electronegative yet they're considered deactivating. Why?

On my lecture notes, I have one section that says
"if Q is an electron withdrawing group then attack on the ring is slowed because this leads to additional positive charge on the ring".

While another section says "all meta directing groups have either a partial or full positive charge on the atom directly attached to the aromatic ring."


texts:
Recently, I am learning the production of soluble and insoluble salts. My friend and I have done this experiment at the school lab.

We wanted to taste them to see whether they are salty are not. The teacher luckily stopped us from doing that.

So without tasting them, I would really like to know whether all salts are salty.


texts: Entropy change of surroundings and system

texts:
The entropy change of the surroundings can be calculated by the equation $dS_{sur}=\frac{dq}{T_{sur}}$ regardless of the path (irreversible or reversible).

The argument is that because the surroundings may be approximated as either constant volume or constant pressure, the heat absorbed/released by it is equal to the internal energy or enthalpy change, respectively. As both are state functions, it does not matter if the path taken was reversible or not, the changes would be the same for both, so $dU_{sur,rev}=dU_{sur,irrev}$ and $dH_{sur,rev}=dH_{sur,irrev}$. However, $dH=dq$ for constant pressure, and as per definition $dS=\frac{dq_{rev}}{T}$, the initial equation follows.

This is somewhat the way my book derives the formula. It seems to be inconsistent to me because it equals $\frac{dq_{rev}}{T}=\frac{dq_{irrev}}{T}$, which some pages after the book says that is not the case and uses the fact that $dq_{rev}\geq dq_{irrev}$ to derive the Clausius inequality.
I do understand the Clausius inequality and its derivation, however I do not understand why is it that it is not used to calculate the entropy change of the surrounds, only the system. The arguments for its derivation seem to apply to the first case as well.

Similar question that has no answer: Entropy change of surroundings


texts:
If the pKa of Glycerol is 14.15. How do you calculate the pH for it?

I assume that the Henderson-Hasselbalch derivative that works for weak acids and bases is not applicable here.


texts: How would one favor the formation of p-TsCl over o-TsCl in the chlorosuflonation of toluene?

texts: I found an old synthesis of $\ce{o-TsCl}$ that purportedly gives a yield of $85\%$ here and was wondering how, still using chlorosulfonic acid, I could favor the formation of $\ce{p-TsCl}$ instead.


texts: Possible to Calculate Electronic Charge Distributions/Densities for Organic Molecules?

texts:
I was wondering if there are any programs that can calculate the electronic charge distributions around an organic molecule, possibly in the form of a volumetric charge volume density? I am reading up about using DFT programs that (correct me if I'm wrong) I believe may be able to tell us something about finding the charge density.

I'm working on a project that involves obtaining the electric field values surrounding an organic molecule. My current approach involves finding a function for the molecule's electronic volume charge density and doing a volume integral to get the electric field.

Is this a potentially valid method? If not, what else should I look into?


texts: How to interpret the rate constants of in-vivo racemization of thalidomide?

texts:
The article by Eriksson et. al. found that thalidomide undergoes chiral inversion in vivo. It found the mean rate constants too, $0.17~\mathrm{h^{-1}}$ (R to S) and $0.12~\mathrm{h^{-1}}$ (S to R).

I have no idea what those numbers mean. Does that mean 17% of the R-thalidomide becomes S-thalidomide every hour?

Reference
Eriksson, T.; Bjöurkman,S.; Roth, B.; Fyge, Å; Höuglund, P; Chirality 1995, 7 (1), 44-52. (PubMed)


texts: Are alkaline conditions required for Maillard reaction?

texts:
The Maillard reaction, a form of non-enzymatic browning, refers to a cascade of chemical reactions that frequently occurs in the cooking of foods (e.g. baking of pastries, roasting of meats). It primarily starts as a reaction between amines and carbonyl compounds. It is stated on the Wikipedia page that the reaction is accelerated by alkaline conditions:

  This process is accelerated in an alkaline environment (e.g., lye applied to darken pretzels), as the amino groups ($\ce {RNH3^+ → RNH2}$) are deprotonated, hence have an increased nucleophilicity.

Similar tips on using alkali to hasten the Maillard reaction have also been propagated on various cooking websites, even on cooking.stackexchange. In this post, I would like to investigate the chemistry behind this piece of advice.

The use of alkali is chemically sound since the first step of the initial stage of the reaction is the formation of a Schiff base from the amine and the carbonyl compound. However, is it a bit far-fetched to say that since the first step is accelerated, the entire reaction cascade is similarly sped up significantly?

More importantly, as I have mentioned previously in this post: Conditions for imine formation, the reaction is primarily catalysed by acid and not by base. Yes, nucleophilicity of the amine increases. However, the alkali medium does not facilitate the leaving of certain groups. Thus, the overall effect of the alkali may not be exactly favourable.

The fact of the matter is that alkalis, such as baking soda, have been used in cooking for a long period of time. Thus, it certainly does improve the taste of food by some mechanism. However, I question whether this mechanism is indeed the hastening of the Maillard reaction.


texts:
Is $\ce{CCl_4}$ an electrolyte all by itself, or does something need to be added to it so that it becomes an electrolyte?

Also, is it weak or strong?


texts: Difference between Particle in a Box and Harmonic Oscillator approximations

texts: Why in the particle in a box model do the values of n begin at 1 but in the harmonic oscillator they begin at 0? I understand what the wave-functions and their corresponding probabilities look like and that the PIB has 0 nodes for n=1 which means the number of nodes is n-1, so for n = 0 it would have -1 nodes which is physically unreasonable. But I do not understand why the PIB cannot have n=0 whereas the Harmonic oscillator can.


texts: Can one predict the entropy change for aqueous phase reactions without calculation?

texts:
I have seen several sources that claim aqueous solutions always have more entropy than pure liquids or solids, however, some aqueous ions have negative standard entropy.  This opens the possibility of solubility reactions with negative standard entropy change.  For example,
$$\begin{align}
\ce{NaF (s) &<=> Na+ (aq) + F- (aq)}&&\Delta S^{\circ} =-6.26 \ \mathrm{J/(mol\cdot K)}\\
\ce{AlCl3 (s) &<=> Al^3+ (aq) + 3 Cl- (aq)}&&\Delta S^{\circ} =-261.5 \ \mathrm{J/(mol\cdot K)}\\
\ce{AlF3 (s) &<=> Al^3+ (aq) + 3 F- (aq)}&&\Delta S^{\circ} =-429.58 \ \mathrm{J/(mol\cdot K)}
\end{align}$$

I have used thermodynamic data from this source.

So it seems to me that it is impossible to easily predict whether the entropy change for a reaction involving an aqueous phase is either positive or negative without calculation (unless a gas phase is involved, in which case the aqueous phase is moot)

Am I missing something, or are all the sources that claim an aqueous phase always has more entropy than a liquid phase oversimplifying the situation or just plain wrong?

I brought up the example of aluminum chloride to a chemistry instructor who then said that it is possible for molecular compounds to have negative entropy change when dissolved, but never for ionic compounds.  Yet both sodium fluoride and aluminum fluoride are ionic, and seem to have a negative entropy change when dissolved.

I understand why the standard entropies are negative, and about solvation shells. What I'm asking is whether the change in entropy can be predicted at a glance instead of looking up values and calculating as I have done.  Many textbooks claim all of these reactions should have a positive $\Delta S^{\circ}$ simply because "aqueous solutions have more entropy than solids or liquids." The instructor I talked to claimed that $\ce{AlCl3}$ will have negative $\Delta S^{\circ}$ because it is a molecular solid whereas $\ce{NaF}$ and $\ce{AlF3}$ should have positive $\Delta S^{\circ}$ because they are ionic solids. Are the textbooks and this instructor incorrect?


texts: Does the temperature of water change during electrolysis?

texts:
Applying an electric potential to impure water splits water into its constituents H/O.

Does the temperature of the electrolyte change during this electrolysis?


texts: Can i use deionized water instead of distilled water

texts:
My question is really simple : can i use deionized water instead of distilled in experience ?
Because i have a air dehumidifier at home and it produce a lot of deionized water
I know that deionized water ($\ce{diH2O}$) is :

  Water that has had almost all of its mineral ions removed, such as cations like sodium, calcium, iron, and copper, and anions such as chloride and sulfate.

And distilled water ($\ce{dH2O}$) is :

  Water boiled and then condensed into a clean container, leaving solid contaminants behind

So basically the difference between $\ce{diH2O}$ and $\ce{dH2O}$ is that $\ce{dH2O}$ keep his ions mineral right ?
Can i use deionized water anyway ? Or not ?


texts: I have a sodium silicate sealant in my car and need to find a way to soften it

texts: Poured Blue devil sealant and found that it clogged my engine. Can someone who knows about chemistry and cars maybe give me any ideas on how to solve this issue?


texts: Predicting orbital angular momentum effects on magnetic moments

texts:
For metal complexes with $A_{2}$ or $E$ ground state terms there is angular momentum contribution to the magnetic moment which is generally positive for more than half-filled subshells and negative otherwise, and related to the spin-only magnetic moment by
$$m_\mathrm{eff} = m_\mathrm{SO}\left(1-\frac{\alpha\lambda}{\Delta}\right)$$

where $\Delta$ is the ligand field splitting parameter, $\alpha$ is the orbital angular momentum degeneracy of the state and $\lambda$ is a constant.

My questions:

When do exceptions to this behaviour occur ? For example I have found that $\ce{Co(bipy)_{3}(ClO4)}$ has a lower experimental magnetic moment than the spin only formula predicts despite being a $\ce{Co(I)}$ (d8) compound with a $^{3}\!A_{2g}$ ground state, but I do not understand why.
Is the deviation from the spin only formula always positive for $T$ states ? If not can we predict its sign similarly ?
EDIT: a simple way to do this is via Hund's third rule. If the d-orbitals are half or more full, the highest J state will be lowest in energy, and then the deviation for the T state will be positive ! Exactly why is probably rather subtle.


texts: Why are electrons filled in fourth shell before the third shell is filled?

texts:
I am a beginner and am learning about atomic structure and I am getting confusions regarding the aufbau principle.
It is said that the electrons will be filled first in lowest available energy level. But according to aufbau principle electrons are filled in $\mathrm{4s}$ orbital before filling the $\mathrm{3d}$ orbital. Similarly,electrons are filled in $\mathrm{5s}$ before $\mathrm{4f}$.
But I am also taught that if $n$(principle quantum number) increases,the size of the orbital also increases. By size I mean the maximum distance from the nucleus.
So accordingly, $\mathrm{4s}$ orbital should have greater size than $\mathrm{3d}$. Similarly $\mathrm{5s}$ should have greater size than $\mathrm{4f}$. Hence $\mathrm{4s}$ as well as $\mathrm{5s}$ are farther from nucleus as compared to $\mathrm{3d}$ and $\mathrm{4f}$ respectively. Thus they have more total energy and hence electrons should be filled in $\mathrm{3d}$ and $\mathrm{4f}$ before $\mathrm{4s}$ and $\mathrm{5s}$ respectively.
But the above stated doesn't happen. My confusion is, "Why isn't this line of thinking correct?"
Here is a diagram depicting that $\mathrm{4s}$ is bigger than $\mathrm{3d_{xy}}$.


texts:
The wikipedia page on cyclononatetraene says that the aromatic cyclononatetraenyl anion can be synthetised by a rearangement of 9-chlorobicyclo[6.1.0]nona-2,4,6-triene.

My first idea on how to synthetise this compound is to react cyclooctatetraene with chlorocarbene $(\ce{:\!CHCl})$. However, in contrast to dichlorocarbene $(\ce{:\!CCl2})$, chlorocarbene $(\ce{:\!CHCl})$ is much less stable. Can it be synthetised by an action of a strong base on dichloromethane?

It seems, from this pdf, that $t$-$\ce{BuOK}$ will make $\ce{:\!CPhCl}$ from $\ce{CHPhCl2}$. Is it, however, a strong enough base to deprotonate $\ce{CH2Cl2}$? Or must some stronger one, e.g. LDA, be used?


texts: I want to extract the $\ce{KI}$ component of the Lugol solution, is there a method to do it? If not, how can I make a $\ce{KI}$ solution?


texts: What does "less hindered hydrogen" mean?

texts:
In a book they have given a statement,

  In the process of pyrolysis of esters, esters having  beta hydrogen are heated at high temperature and then alkenes are formed along with carboxylic acid.
  If there are two beta hydrogens then beta hydrogen having less hindrance will participate in the reaction.

In the last line, what do they mean by less hindered hydrogen?


texts: when reading about polar covalent bond I came across the rule called 'Fajan's Rule' but could not find the explanation nor the derivation


texts: Buffer Solution Problem (Acid/Conjugate Base)

texts:
To create a buffer mixture, I understand that mixing an equal concentration of a weak acid and it's salt (conjugate base) will form an acidic buffer.

However, why is it that when $\pu{25 cm^3, 9.100 M}$ $\ce{CH3COOH}$ and $\pu{50 cm^3, 0.100 M}$ $\ce{CH3COONa}$ can also form a buffer solution?

Is there any specific rule for the creation of buffer solution from weak acid and it's salt?


texts: Why is the most probable KE for a monoatomic ideal gas exactly 1/3 of its average KE?

texts: The most probable value of the kinetic energy for a monoatomic ideal gas can be calculated by setting the first derivative of the probablity density function equal to $0$, this turns out to be $\frac{1}{2}kT$ which is $\frac{1}{3}$ of the average value, $\frac{3}{2}kT$ what is the physical reason behind this?


texts: Does ethanol "decompose" or "remove" phosgene from chloroform?

texts:
A question I was asked was: "Why is ethanol added to chloroform bottles?". I know that chloroform can be slowly converted to poisonous phosgene gas, and that ethanol is added to prevent phosgene levels from rising. However, the options I was given were:

It decomposes phosgene by converting it into ethyl carbonate.
It removes phosgene  by converting it into ethyl carbonate

Is there a difference between the two wordings, and is one more correct than the other? The answer is supposedly "decomposes".


texts: What are the preferred IUPAC names of these two compounds?

texts:
In a recent homework assignment we are asked to give IUPAC name to the following two compounds:

I am not asking this question for homework help -- for that purpose I got both names correct, to the extent of the standard given in my orgo textbook. What intrigues me is that compound naming softwares seem unable to agree upon the names of these compounds.

For structure I: (MarvinSketch is consistent with homework answer, because bromo comes alphabetically before bromobutyl)

ACD/ChemSketch (freeware) 2017.1.2: 4-(2-bromobutyl)-6-methyloctan-3-ol
MarvinSketch 18.4: 6-bromo-4-(2-methylbutyl)octan-3-ol

For structure II: (ACD/ChemSketch is consistent with homework answer, because this name recognizes 3 substituents, while the other recognizes only 2)

ACD/ChemSketch (freeware) 2017.1.2: 4-(2-bromobutyl)-6,6-dimethyloctan-3-ol
MarvinSketch 18.4: 6-bromo-4-(2,2-dimethylbutyl)octan-3-ol

Is it because IUPAC rules are so complicated they can be only followed by hand, or because the tie-breaking rules presented in textbooks are too simplistic to give preferred names in every case?


texts: It seems like the first molecule has a bond order of $1$, the second and third have a bond order of $7/6$ and the fourth molecule has a bond order of $3/2$. Why is the answer not $4 < 2 = 3 < 1$?


texts: Classification of oxides,transition elements

texts:
I understand  what  basic,acidic and amphoteric oxides are.
But how do we classify oxides on the basis of metallic nature?Explain how we can deduce if the oxide is metallic or not.
For example,what does it mean when it is stated that "CrO2 is a metallic oxide."

This was an answer to one of the questions in an exam that I wrote recently.


texts:
Are the half-reactions used in analyzing redox reactions a real thing or are they a conceptual shortcut?

Is there a way to, however briefly, run a half-reaction by itself without the corresponding other half?  For example, reduce metal atoms to metal ions without the corresponding oxidation half-reaction?


texts: As adjectives, not in a math context: 'different' vs 'differential'

texts:
I looked up  differential, but still don't savvy why the books below use 'differential' rather than 'different' and vice versa.

Advanced Organic Chemistry: Part A: Structure and Mechanisms by Francis A. Carey, Richard J. Sundberg. p 211.

Electroanalytical Chemistry: A Series of Advances
edited by Allen J. Bard. p 195.

Tietz Textbook of Clinical Chemistry and Molecular Diagnostics - E-Book by Carl A. Burtis, Edward R. Ashwood, David E. Bruns. p 519.


texts: One special branch in chemistry is allotted to compounds of only one element (carbon). Is it justified when there are more than 115 elements and their compounds but not with any special branches?


texts:
My textbook says that Clemmensen Reduction cannot take place in the presence of an acid-sensitive group and the Wolf Kishner reaction won't happen in the presence of a base sensitive group, citing $\ce{-OH}$ (alcohol) and $\ce{-X}$ (halogens) as respective examples.
However, I read from somewhere else that:

Acid sensitive groups are groups which are electron donors or have spare electrons, like $\ce{NH3}$. Base sensitive groups are groups, which are in need of electrons or have empty orbitals, like $\ce{BH3}$.

This seems incorrect to me as Halogens are clearly not in need of electrons. I can see why alcohols would be acid-sensitive but why would Halogens be base-sensitive?


texts: Separation techniques for different organic compounds

texts:
Select the best (most appropriate, easiest, fastest) separation technique for each pair of compounds shown below:

  Separation techniques:

  evaporation under reduced pressure
  column chromatography
  water-diethyl ether extraction
  acid-base extraction

This requires knowledge of what compounds are separated most efficiently/appropriately by what separation technique. Since I did the labs separately I can only attempt to try to meld the concepts together.

Pair 1 is a carboxylc acid and chlorodiene. Both are polar.
Pair 2 is an ether and hydrocarbon. One is polar the other nonpolar.
Pair 3 looks to be an ester and cyclodiene. One is polar and the other slightly polar.

My attempt:

Based on the acid I'd use acid-base on pair 1.
Pair 2, since one is polar and the other nonpolar, seems like it needs liquid-liquid extraction (water-diethyl ether extraction)
Pair 3 are polar. Unsure of this one. They'd be slow on a column. Evaporation is based on a low boiling point.


texts: Which natural orbitals are better for CASSCF calculations for organic diradicals?

texts:
I am trying to perform CASSCF calculations for a series of diradicals. As input orbitals I have used two types of natural orbitals. One is unrestricted natural orbitals and the other MP2-based natural orbitals. From both sets I am getting different trend for the properties I am trying to look into.
Can anyone suggest me which is the better way to know which results are reliable ?
I have used ORCA 4.0 version.


texts: What is the significance of antinode at r=0 in the plot of radial wave functions of s-orbitals?

texts:
Why should there be an antinode at r=0?
I can comprehend the presence of node at r=0 for p,d,f orbitals; but I don't understand that of s-orbital.
Is there any intuitive approach?


texts:
Consider a solid wall consisting of three layers where the layers are of equal
  thickness but made out of different materials: $\ce{Layer 1}$ is made out
  of copper (high thermal conductivity), $\ce{Layer 2}$ is made out of a
  highly porous ceramic (low thermal conductivity), and $\ce{Layer 3}$ is
  made out of concrete (medium thermal conductivity).

  How does
  the steady state temperature profile inside the wall look like?

I'm not sure if this question is asked in a way to mislead me into drawing the T-profile as (2) when at steady-state it actually should look like (1).

I apologize if this question is seen as off-topic or simple, but I would appreciate it if someone would explain if I am correct in saying that the T-profile at steady state should be linear.

Thank you!

(1)
 (2)


texts: Why are HgO and CdS compounds colourful?

texts:
We know that the electron configuration in $3d$ orbitals of $\ce{Zn^2+}$, in $4d$ orbitals of $\ce{Cd^2+}$ and in $5d$ orbitals of $\ce{Hg^2+}$ ions are completely same.

Then why the compounds of $\ce{Hg(II)}$ and $\ce{Cd}$, such as $\ce{HgO}$, $\ce{CdS}$ radiate versatile colour where $\ce{ZnO}$, $\ce{ZnS}$ are white?


texts: Are there any exceptions to Le Chatelier’s principle?

texts:
Peter Atkins says

In introductory chemistry, we meet the empirical rule of thumb known as  Le Chatelier’s principle:
When a system at equilibrium is subjected to a disturbance, the composition of the system adjusts so as to tend to minimize the effect of the disturbance.
For instance, if a system is compressed, then the equilibrium position can be expected to shift in the direction that leads to a reduction in the number of molecules in the gas phase, for that tends to minimize the effect of compression.Le Chatelier’s principle, though, is only a rule of thumb, and to understand why reactions respond as they do, and to calculate the new equilibrium composition, we need to use thermodynamics.

That Le Chatelier’s principle, is only a rule of thumb, and thermodynamic calculations need to be done to determine new equilibria.
So are there any exceptions to this rule of thumb ??


texts: Is a highly oxidized element more electropositive than a lesser oxidized counterpart?

texts:
My issue

I have a significant problem with the following excerpt from a general chemistry text:

Note that ON stands for oxidation number (state). The excerpt is with regard to polyatomic anions - specifically, chloride ion and its related polyatomic anions.

  It now follows that as oxygen-atom content increases by one, ON for the atom of variable ON increases by two because each added O has an ON of -2 and O is more EN than the atom of variable ON - thus, bonding O to this atom makes the atom more electropositive.

If electropositivity is defined as the ability to stabilize positive charge, how does a highly partially positive central chlorine atom have this ability? How  can EP increase?

If electropositivity is more formally defined as the ability for an atom to give up electrons within a covalent framework (note that this is the converse of the definition of electronegativity), how exactly does a highly oxidized chlorine atom, such as the chlorine atom in the perchloric ion, have the ability to give up any more electrons? It already has no valence electrons to give up if we stick with an ionic model to assign oxidation states!

If we look at this intuitively, and agree that more electropositive elements are more likely to bear positive charges - i.e. sodium (Na) is highly electropositive and it is very easy for Na to be stripped of its one electron to become isoelectronic with a noble gas - then why would chlorine become more electropositive as it is further oxidized?

If we consider the successive ionization energies of chlorine, they become more and more massive! So how in the world would chlorine be more electropositive (willing to give up electrons within a covalent framework) as it is further oxidized?

(I do recognize that ionization energy of an electron is not a measure of electronegativity but still it is highly correlated with EN).

Professor's response

My professor, respectfully, didn't offer much a defense. He said something about how positive charge doesn't exist because it's the lack of valence electrons rather than the presence of something material. This, to me, is sidestepping the argument.

He also asked me which would be more likely to bear a positive charge - Cl or O? Obviously Cl; it has electrons way further from the nucleus than oxygen, so of course Cl would more easily be stripped of an electron than O. However, this again, I believe, is a mistake, because we cannot consider electronegativities of elements and expect them to hold within ions and molecules. Carbon, for example, isn't very electronegative at all. But no one doubts the electron-withdrawing powers of a carbonyl carbon, or better yet, the electron-stabilizing powers of a ... CARBOCATION.

Further, last semester, I distinctly remember correcting him with regard to this electronegativity business; he said that a more negative ion would be more electronegative. I had to correct that statement; a more negative ion would be less able to stabilize valence electron density and less able to attract valence electrons if bound within a covalent framework, so the correct term would be instead more electropositive.

Does anyone here agree with me? Sometimes I feel that it's not the argument that matters as much as your tenacity and ability to present the argument. I lacked both tenacity and presentation skills when presenting the above argument.

I came close to telling him that his entire take of electronegativity was fundamentally flawed when I told him that "I don't associate a positive charge with electropositivity and a negative charge with electronegativity" but that was met with nothing to the contrary (which would have been welcome!) - because no, positive charge has nothing to do with electropositivity; in fact, it suggests the opposite of electropositivity!


texts:
Is there any way of predicting whether a precipitate will be colored? I know that for solutions, transition metal ions with unfilled d-orbitals will have color because of d-orbital splitting in the complex ions. However, this isn't applicable to precipitates because those are just ionic solids, not complex ions.

For example, $\ce{PbI2}$ is a yellow solid, and $\ce{Al(OH)3}$ is white. Is there a way to predict that $\ce{PbI2}$ will be colored while $\ce{Al(OH)3}$ will not be, or is it something we have to memorize to know?


texts: Basicity Alteration Due To Ortho Effect In Methoxy Aniline System

texts:
I wanted to ask something more in reference to this question.

Suppose instead of toluidine, 2-methoxyaniline and 3-methoxyaniline are present. Now, why is 2-methoxyaniline more basic than 3-methoxyaniline (even though 2-methoxyaniline has reduction of basicity due to ortho-effect but 3-methoxyaniline does not)?
Also what would be the correct order of basicity if nitro group was present in place of methoxy group? Would ortho-effect still take place?


texts:
We know that isodiaphers have same difference in neutrons and protons, but I encountered another definition:

  Atoms which have same isotopic axis are called isodiaphers.

I don't know what it means by "isotopic axis". Please try to explain in simple words.


texts: What takes place in this transformation of the 1,3-dicarbonyl?

texts:
I was just looking at a particular synthesis method on the Organic Chemistry Portal when I saw a particularly puzzling step, involving a 1,3-dicarbonyl compound. The step which I am puzzled by is shown here:

The second step, acid-catalysed esterification is unambiguous. It is the first step which opens the ring which concerns me. The fact that esterification occurs in the second step seems to suggest that the product of the acid-catalysed ring opening in the first step is a carboxylic acid and I simply cannot see how it can possibly form. Would someone kindly enlighten me on step 1?


texts:
Given the value 380 PaK^-1, how do I convert Pa to Jdm-3?

I know that 1 joule = 1 Nm, and that 1 pascal = 1 N/m^2.

But where does the dm^-3 (or L) come into this? I don't know where to start.


texts: can i calculate equilibrium constant of this reaction?

texts:
Good day,
i had organic chemistry labs. And we had this reaction:
$$\ce{(CH3)3COH + HCl -> (CH3)3CCl + H2O}$$

My question is:
how do i explain my yield of reaction is only 40%?

My theory is:
reaction is reversible so the K isn't so high and that lead to yield 40%.
If my theory is right please explain me how to calculate K?

I had these informations:

V$\ce{((CH3)3COH)}$ = 10 ml

V$\ce{(HCl)}$ = 20 ml
HCl was concentrated.

Thank for answers.


texts: In HPLC, how does column diameter affect the retention time?

texts:
I am using a smaller diameter column than my previous one keeping all other factors such as stationary phase, solvent, solvent gradient constant. (Obviously, flow rate will be less in smaller column). I would like to know will changing the diameter affect the retention time of my target?

I searched and got results like this and this But they do not mention about the effect of column diameter on retention time. Moreover, I am weak in understanding mathematical equations.


texts: Why is the melting point of magnesium nitride less than that of beryllium nitride?

texts:
Why is melting point of $\ce{Mg3N2}$ lower than that of $\ce{Be3N2}$ ?
I have two reasonings:

The lattice energy of $\ce{Be3N2}$ is higher than that of $\ce{Mg3N2}$ so accordingly the melting point of the former should be higher
Both of them form ionic nitrides. Since $\ce{Mg3N2}$ has more ionic character it should have higher melting point than $\ce{Be3N2}$

Since both of these are contradicting, I wish to ask which one is correct? And if both are correct in some way, which one should be prioritized over the other?
Can this be determined or is it experimental?


texts: Does rearrangement take place in the reaction between ethenylcyclohexane and iodine chloride?

texts:
I am stuck at the point if a non classical carbocation should be formed on the 2nd Carbon of the side chain.
One of my friend gave me the following suggestion:
I guess $\ce{ICl}$ will break in the form $\ce{I+/Cl-}$ so considering this if $\ce{I+}$ gets attached to the lower side of the chain then the carbocation formed on the 2nd element of the chain will not be a non-classical carbocation (because $\ce{I+}$ won't give a lone pair to the carbocation as it is electron deficient itself). A simple carbocation will be formed, and the rearrangement will be possible.
After rearranging it will get its most stable position on the carbon joining the ring and the chain so there the $\ce{Cl-}$ attacks and the requires molecule is formed.
I suspect this is wrong, What is the solution to this problem?


texts: What happens to the bleach after mopping?

texts:
At home, I clean the tiled floors by mopping with highly diluted bleach.  After mopping, I let the floor dry.  What happens to the acid in the bleach?

Will it crystallize on the floor, stay there invisibly in solid form, and get solved again next time the floor gets wet?  Will it instead evaporate, or turn to fine dust that floats in the air and leaves through the window?  Will it decompose in some sort of chemical reaction?


texts: Is there a pH range for "neutral" detergents?

texts:
There exist many home made pH scales like these

But do any of you know if there is an "official" scale that defines if a neutral detergent is 7 sharp or within a range _______?


texts: Is it wrong to say that Density Functional means that Electron Density is a function of the orbitals (wave function) of all electrons in 3 dimensions, if so, why ?


texts: Why mustn't the sample be dipped in the mobile phase in paper chromatography?

texts:
As the title says it, I am curious about why the sample (ie, an extract of plant's chlorphyl transferred onto paper) must not be dipped into the mobile phase (ie, the solvent which goes up the paper)?

My first guesses are that it is because the sample would dissolve into the solvent and only a small portion of the sample would go up the paper, but I am really keen to know if there is more to it than just this.


texts: Is there a mathematical and rigorous way to prove whether a given function is a state function or a path function?

texts: My textbooks have explained why Enthalpy, Entropy, Internal Energy, Gibbs Free Energy are state functions or path functions only intuitively and with examples. But that never fully satisfied me. Is there any mathematical way to prove whether a given function is a state function or path function?


texts: What is the difference between a phosphoryl group and a phosphate group?

texts: I am looking at covalent modification of enzymes and I found out that only one of these types is phosphorylation. But I do not understand what the difference between the a phosphate and a phosphoryl group is in terms of nomenclature.


texts:
Consider the molecular formula $\ce{CH2=CH-CH=CH-OH}$ $(\ce{C4H5OH})$. Tell the types of bond, hybridizations, bond angles and geometry of this compound.

I didn't have any trouble with the first 3 topics.
Carbon hybridizes in $\mathrm{sp^2}$ and oxygen hybridizes in $\mathrm{sp^3}$.
Each carbon makes 3 $\sigma$ bonds and 1 $\pi$ bond and the oxygen makes 2 $\sigma$ bonds. The angles of the bonds $\ce{H-C-H}$, $\ce{H-C-C}$, $\ce{C-C-C}$ are 120 degrees and the angle of bond $\ce{H-O-C}$ is 109 degrees.
My problem is with the geometry. How can I deduce it? It doesn't seem to be one of the standard geometries.


texts:
Disclaimer: I'm asking this because I am curious.  Not because I'm actually handling nitric acid.

In another answer I was reading, the poster mentioned that if you spill nitric acid, you shouldn't pour water on anything but a small spill, because it will generate heat (maybe enough to flash-boil the water?), but if you spill nitric acid on yourself, you should have an emergency shower ready.

Except, wouldn't the emergency shower be using water and cause the exact same problem?  Is this just a case of deciding that possible burns from a hot liquid, while under a cold shower are much better than definite acid burns?


texts: Acid catalysed bond hydrolysis in 3-bromobut-1-ene

texts: I came across this doubt while solving a problem. I can't understand to which path (1 or 2) I should give priority, as both sound equally good to me.


texts: Why are the radial wavefunction and radial distribution function different?

texts:
I'm having trouble understanding the following two graphs, which are the radial wavefunction of the hydrogen 1s orbital and the corresponding radial distribution function:

Specifically, why is the radial distribution function zero at $r = 0$, but not the radial wavefunction?

Also, why does the radial distribution function have a maximum at the Bohr radius $a_0$?

(Mathematica input for the graphs: Plot[{2*Exp[-x], 4*Exp[-2 x]*x^2}, {x, 0, 6}, AxesLabel -> {r/Subscript[a, 0], Subscript[f, "1s"][r]}, PlotRange -> {{0, 6}, {0, 2}}, PlotLegends -> {"Radial wavefunction", "Radial distribution function"}, BaseStyle -> {FontSize -> 14}, ImageSize -> Medium])


texts: How do I identify the compound(s) that formed from a failed synthesis of another compound?

texts:
A general answer to the question is great, but specified to my problem is very much welcomed.

My team had a lab project — to synthesize chrome alum crystals.

We first dissolved $0.3 \, \rm g$ of potassium dichromate on $4 \,\rm mL$ of $1 \,\rm M$ sulfuric acid, then added $2 \,\rm mL$ of $99\%$ ethanol and let it rest for a day. There were some crystals formed, but the color was orange (it should've been purple).

From the instruction that we followed, we should heat up the solution, so we did that, and carelessly let the temperature go up past $70 \,^{\circ} \rm C$. It become greenish in color and doesn't form any crystal after a week.
We resorted to evaporating the liquid part and obtained some leftover greenish yellow powder at the bottom which is very much far from the desired chrome alum.


texts: I have found in the textbook that Be has negative electron affinity while Ca has positive why? how can I compare the electron affinity values of these two.?


texts: Apparently it has $sp^3$ hybridization, but I don't understand why. Ammonia ($\ce{NH3}$) seems to me to not require $sp$ hybridization because all of its bond lengths are already equal. It has 3 hydrogens bonded to the $p$ orbitals. Why can't the lone electron pair in nitrogen's $2s$ shell stay put where it is?


texts: How to predict the correct splitting pattern in a NMR spectrum

texts:
If I were to do a simulation and obtain all the chemical shifts and coupling constants between the different atoms, how would I then predict the NMR spectrum with coupling. Without coupling, I just use the chemical shifts and compare those to a base (TMS for example) and then I have all the peak locations and I'm pretty much done. But how do I incorporate all the splittings?

My guess would be to compare the chemical shift difference between two nuclei, $i$ and $j$ with their coupling constant and when $\Delta\sigma_{ij} > J_{ij}$ then I need to split the peaks corresponding to particle $i$ and $j$ but this would mean that coupling between nuclei that are very far apart with a very small $J$ would also be split, which is not really what you want.


texts: 2-methylpropene to tert-butyl alcohol Reaction Mechanism

texts:
Can someone explain what reaction is going on here?
I looked in my list of mechanisms learnt: I find nothing related!


texts: Effect of protecting group on diastereoselectivity of LiAlH4 reduction of α-hydroxyketones

texts:
In the reactions above, taken from Tetrahedron Lett. 1982, 23 (23), 2355–2358, the choice of protecting group on the α-hydroxyl group has a large influence on the diastereoselectivity of reduction.

Why does the benzyloxymethyl protecting group lead to the formation of the anti diol (consistent wiht the Cram chelate model), whereas the tert-butyldiphenylsilyl protecting group gives the syn diol (consistent with the Felkin–Anh model)?


texts: UV-Vis Spectra: Multiple peaks for one component

texts:
I am working on a project in my lab, and we are analyzing capsaicin using HPLC. I am trying to find an appropriate wavelength for the HPLC using a UV-Vis spectrometer. When analyzing the pure capsaicin standard dissolved in methanol, I of course use methanol as a blank. However, I got two peaks, one around 230nm and one at 280nm. Since the system automatically subtracts the methanol, I can't understand why I am getting two peaks.
Anyway, 230 yielded the maximum absorbance, so I used that in my HPLC. I didn't get great results and decided to read some literature on the project. I saw that most other people had a UV-Vis spectrum like mine, but they decided to use 280nm. Why is that?


texts: Isomerization of phosphorylated 2-imino-1,3-dioxalanes into phosphorylated cyclic carbamates

texts:
I found a patent dating back to the Soviet Union. The patent number is 256764, and the patent describes the synthesis of phosphorylated cyclic carbamates. Here is a section of the patent, followed by a translation:

....A method of obtaining n-phosphoryl cyclic urethanes of the general formula [Picture] where R=alkyl, R1= H or alkyl, n=1,2, by the interaction of dichloromethyleneamides of phosphoric acid with glycols in the presence of organic bases, for example triethylamine, in organic solvent under cooling of the reaction mixture, preferrably to 0 C, is offered. In the case of using ethylene glycol or 1,2 propyleneglycol, and also 2,3- or 1,3 butyleneglycol, first, it seems, n phosphoryl 2-imino-1,3-dioxolanes are formed, which are converted by means of elevated temperatures to the desired products.
The rest of the patent gives an example of such synthesis.
It seems to me that the authors are suggesting that this reaction happens after the glycol is reacted with a dichloromethyleneamide of esters of phosphoric acid:

This looks similar to a Chapman Rearrangement, but, to my knowledge, a Chapman Rearrangement requires the presence of aromatic groups, so this isomerization reaction is not a Chapman Rearrangement. How and why does this isomerization reaction occur? What is the reaction mechanism?
Link to patent: https://patents.su/2-256764-sposob-polucheniya-n-fosforilirovannykh-ciklicheskikh-uretanov.html


texts: Reaction of ethylacetoacetate with Iodine

texts:
A "reaction map" in my lecture handout suggests that the product of this reaction is:

So, basically overall it just merges two ethylacetoacetate molecules together at the central carbon. What is the mechanism for this? My thoughts are to swap the acidic proton for an Iodine atom by making the enol (in acidic conditions to avoid iodoform reaction) and react with $I_2$. Then, the enol of another molecule of EAA substitutes the Iodine to make the product. However, I don't know whether this is $S_N1$ or $S_N2$. Typically alkylation is $S_N2$ (I don't know why, please explain if you can) but in this case its a bulky secondary substituent and the solvent is protic (acidic conditions). Surely it's $S_N1$, right?


texts: Degree of association, van't Hoff factor and dissociation constant

texts:
$\ce{CH3COOH->CH3COO- + H+}$
  \begin{array}{c|c c c}
  \mathbf{Initial} &  \mathrm{1~mol} & \mathrm{0~mol} & \mathrm{0 ~mol} \\\hline
  \mathbf{Final} &   \mathrm{1-\alpha ~mol}&\mathrm{\alpha ~mol}&\mathrm{\alpha~ mol}
 \end{array}
  Where $\alpha$ is the degree of dissociation.

Therefore, $i = 1-\alpha+\alpha+\alpha =1+\alpha$, and $\alpha=(i-1)$.
This is what is written in my book. And I understand this.

  $\ce{CH3COOH->CH3COO- + H+}$
  \begin{array}{c|c c c}
  \mathbf{Initial} &  \mathrm{c~ mol}&\mathrm{0~mol}&\mathrm{0~ mol}\\\hline
  \mathbf{Final} &   \mathrm{c(1-\alpha)~ mol}&\mathrm{c\alpha~ mol}&\mathrm{c\alpha~ mol}
\end{array}
  Where $\alpha$ is the degree of dissociation.

Therefore,
$$i = \frac{c\alpha+c\alpha+c(1-\alpha)}{c} =1+\alpha$$
 (same as in case 1), and $\alpha=(i-1)$.

$$K_a=\frac{c^2\alpha^2}{c(1-\alpha)} = \frac{c\alpha^2}{(1-\alpha)}$$
This is also written in my book, and I understand this, too.

But, my question is why can we not use the former method to calculate the dissociation constant, $K_a$, which will give me:
$$K_a =\frac{ \alpha^2}{(1-\alpha)}$$
as opposed to what I got in the second (and the correct) case, which was:
$$K_a = \frac{c\alpha^2}{(1-\alpha)}$$
I can see the difference of a $c$ in the two equations, but can someone explain why do we get the difference?


texts: Quantum Chemistry: Small imaginary frequencies

texts:
I am running a freq calculation on a geometry optimized structure using the ORCA quantum chemistry program. The output of the freq. calculation contains small neg. frequencies. Normally, these are considered to be saddle points, and thus would lead to the conclusion that the geometry does not represent a ground state.

freq.             IR Int.
-17.6900          0.000
-16.8900          0.000
-10.6600          0.000
6.4000            0.000
11.7200           0.000
... more small frequencies with IR Int. 0
30.3700           0.000
36.7000           19.3544

However, I am wondering if this is really the case, as the output also assigns an IR intensity of 0.000 to these modes, and states that "The first frequency considered to be a vibration is 14", which is the first positive mode. I am a little bit stuck, as obviously a negative frequency shouldn't appear in the IR spectrum, so does ORCA just removes those frequencies from the IR, even though they are there? Or does the IR-Intensity of 0 imply that the negative frequencies are actually just a precision error of the calculation, and I can still assume the structure to be a ground state.

Normally, the criterion is "no negative frequencies". On the other hand, not much energy should be stored in these modes, so I wonder how this will affect the computed energies.


texts: What is the full mechanism for oxidation of toluene to benzoic acid using permanganate?

texts:
I have managed to get some of the way (I think):

I am particularly interested in the full mechanism i.e. all the curly arrows that take you from toluene right through to benzoic acid.


texts: Does adding solutes to water alter its triple point? If yes, how do we find the new temperature and pressure of this point?


texts: How to determine the hydroxide ion concentration in an acidic aqueous solution?

texts:
When doing a titration with $\ce{HCl}$ and $\ce{NaOH}$, both being strong and dissociating completely, if you add a volume of $\ce{NaOH}$ that is less than needed to reach the equivalence point, you say all the $\ce{OH-}$ reacted with an equal amount of $\ce{H+}$ from $\ce{HCl}$.
It would be amount of substance $\ce{HCl}$ - amount of substance of $\ce{OH-}$ = $[\ce{H3O+}]$, and all of the $\ce{OH-}$ is gone, so $[\ce{OH-}] = 0$. But if you take the pH found using the $[\ce{H3O+}]$ value, use that to find pOH and then use that to find $[\ce{OH-}]$ you get a very small value, but not zero. So if I need to report a $[\ce{OH-}]$ value, do I just put 0 or the one gotten from pOH?


texts: Reaction of a non-metal with alkali to produce hydrogen gas

texts: I want to ask that is there any non-metal which reacts with an alkali (NOT alkali metal) to produce hydrogen gas?


texts: Job's Plot or Method Of Continuous Variations

texts:
I was wondering why in order to find the stoichiometry of a complex using Job's Plot, the two compounds must have the exact same molarity. What kind of effect would it have if molarities weren't the same?
Thanks in advance!


texts: Calculating the electrode potential from thermochemical data

texts:
How can I calculate the electrode potential from thermochemical data?

My attempt: I know that the electrode potential is dependent on the enthalpies of: atomisation, first ionisation, second ionisation and hydration. So I summed up all to get $\Delta G$ and used the formula $\Delta G=-nFE$,but I am not getting the same value as given in the table.

Does the electrode potential depends on factors other than those given in the table, or there is something more to it than just addition?


texts:
I use common air to produce ozone. However the gas after the ozone generator does contain $\ce{NO2}$ gas, which I have to remove for the subsequent steps. I tried to remove the $\ce{NO2}$ with a stainless steel gas wash bottle filled with distilled water. This works fine, however the distilled water will subsequently get charged with $\ce{NO2}$ and turn to dilute nitric acid.

After a few days of operation, I have changed the water and tested its acidity. The $\mathrm{pH}$ was around 0.4 - it was possible to etch a copper pipe with it. So the formation of this acid is not very good for the stainless steel gas wash bottle. I have decided to add 2 more stainless steel gas wash bottles and fill the first one with $\ce{H2O + NaOH}$, in order to neutralize the $\ce{HNO3}$. The other two bottles are for capturing the remaining traces of $\ce{NO2}$.

Bottle 1: 5 liter $\ce{H2O}$ + $\pu{15g}$ $\ce{NaOH}$
Bottle 2: 5 liter $\ce{H2O}$
Bottle 3: 5 liter $\ce{H2O}$

Now I have done some ozone measurements with and without these gas wash bottles. The result was as follows:

It seemed as if $\ce{O3}$ would pass through pure $\ce{H2O}$ without any reaction once the solution is saturated and the saturation seems to happen almost immediately.
However the solution with the $\ce{NaOH}$ seems to react the first 2-3 minutes and then suddenly stop reacting, which is actually good, because it does not use up ozone, however I have no clue what is happening in detail.

Here are some charts from the measurement. Upper chart: test of the $\ce{H2O + NaOH}$ solution. Lower chart: test of the $\ce{H2O}$. Note: the lower the value in the chart, the higher the ozone concentration.

The duration of each test was about 5 minutes. I did measure the $\mathrm{pH}$ of the $\ce{NaOH}$ containing solution and it basically did not change due to the ozone treatment. (It was around 12.35 before and after ozone bubbling...)

Any idea what is happening there and why?


texts: Is it wrong to call carbon dioxide "methanedial"?

texts: Since dialdehydes have a carbonyl group on either end of an alkane, is it reasonable to call carbon dioxide "methanedial", or is it that ethanedial (glyoxal) is the first dialdehyde?


texts: Why NaHCO3 added to the water used (Ion Chromatography Suppression)

texts:
I'm studying HPLC detection techniques and stuck on the conductometric suppression technique. It is describing how buffer ions (in my case $\ce{Na+}$ and $\ce{HCO3-}$) are being either adsorbed ($\ce{Na+}$) or protonated ($\ce{H2CO3}$) which makes them electrolytically inactive and leaves just water in the column.

Great! I understand that background conductivity is a problem. What I do not get is why was $\ce{NaHCO3}$ added to the water in the first place?


texts:
I would like to synthesis gold/polyacrylic acid (PAA) Janus nanoparticles in solution.
Any ideas how I can functionalize gold with a photosensitizer and PAA with an antibody so that there would be no other unwanted interactions?


texts: Are these reaction mechanisms correct for Ammonia and Bromide anions acting as a base respectively?


texts: Does milk drinking prevent long-term chemical poisoning?

texts:
I have heard some rumors that drinking milk prevents chemical poisoning. I have done a bit research and some sources confirm that.

Corrosive Poisons
The best first aid is to dilute the poison as quickly as possible. For acids or alkalis (bases), give the patient water or preferably milk or ice cream — one (1) cup for victims under five (5) years; or one (1) to two (2) glasses for patients over five (5) years. Milk or ice cream is better than water because it dilutes and helps neutralize the poison. Water only dilutes the poison. Cornell University

In Case of Poison Ingestion: Drink Milk?
As @Jan pointed out in the case of chemical poisoning the paramedics are immediately called.
So my question is, does milk helps chemical poisoning, e.g., for people that daily work with chemicals or are working in chemical facilities (working with or be in the presence of $\ce{HCl}$, $\ce{HF}$, $\ce{NaOH}$, $\ce{HNO3}$, $\ce{H3PO4}$, etc.)? Or what would be beneficial? And I mean long-term exposure and not immediately threat to life or health.


texts: Reason behind Opaque translucent transparent

texts:
I would like to know the reason that some materials allow light to pass (transparent), blocks it a little (translucent), or completely reflects or absorbs it (opaque.)
I'm don't have a PhD, so answer this in a way that is easy to understand.


texts: Determining the pH of an organic solvent

texts:
Our work is faced with the issue of determining the charge of compounds that are dissolved in chloroform. One could realistically determine the charge of the relevant moieties knowing the $\mathrm{p}K_\mathrm{a}$ of those groups. However,

How would you determine or calculate the $\mathrm{pH}$ of an organic solvent?

An alternative way of asking this question is how would one calculate the concentration of hydronium ions or free protons in a nonaqueous solution.


texts: Determine concentration Using Beer's law

texts: How do you determine concentration of a sample using wavelength and absorbency? Say our wavelength for a sample of Red 40 is 508.50 nm and absorbance is 0.283 when we use 6ml water and 4 ml Red 40. What would be our concentration and the slope ε? This is really frustrating me so any help would be appreciated.


texts: Do non-English speaking countries use the same element symbols?

texts:
The question does sound pretty absurd, but hear me out first. The Periodic Table of the Elements, as I know it, is supposed to be a common standard adopted by the global scientific community.

However, I see a hitch when it comes to a total world-wide acceptance of such a standard.

Every Periodic Table of the Elements that I've seen in print uses the Latin Alphabet, and quite a few chemical symbols are assigned based on the Latin words for the elements ( Fe- Ferrum, Sn- Stannum, Au- Aurum, Cu- Cuprum, etc etc).

Now this appears to be a rather clever compromise reached by the English-speaking countries (the U.S.A, the U.K, Australia, etc) and countries that don't really use English, but use the Latin Alphabet (Germany, France, Spain, etc, etc). Obviously, using a "dead-language" to assign chemical symbols helps eliminate resentment that could rise by favoring one language (say, German) over another (say, English). Well, this appears to be the same logic behind the use of Latin in biological nomenclature too.

Now here's the catch;

How do countries that don't use the Latin Alphabet deal with this?

Alright, it seems credible to believe that Middle-Eastern countries (Arabic) and African countries would use the standard, Latin Alphabet Periodic Table that we use, without complaint. I guess the same goes for former European colonies too.

But what about:

1) Countries like Russia (Cyrillic) and Japan (Kanji), which have made significant contributions to the modern Periodic Table? Since they did contribute quite a bit to the Table, they probably "feel" they have the right to use their own customized Periodic Table using Cyrillic or Kanji characters.

2) Countries that vehemently oppose cooperation with Western countries, and would obviously dismiss the Latin Alphabet Periodic Table as an 'instrument of the West'. For example North Korea.


texts:
In Vogel's organic book, they have mentioned that in the Lund and Bjerrum method of purification of ethanol, magnesium is added, which forms ethanolate. But they said to activate the magnesium first by iodine.

Why is the activation needed and how exactly does this activation process work in the activation of magnesium?


texts:
I've been looking over the lists of materials used together to make metallic glass.

Is it purely coincidental that if you round up/down any decimals from the atomic weight of elements used to construct metallic glass, you're always very close to +-1 (if not at) a prime number for the atomic weight of each element?


texts: Placing the atomic mass and number of an element...

texts: Why are the atomic and the mass numbers of an element flipped in the textbooks relative to the periodic table?


texts: Why does final pH value of buffer solution after addition of acid not depend on amount added?

texts:
I'm brushing up and the example in my book is against my intuition.

  A buffer solution contains 1.0 mol/L acetic acid and 1.0 mol/L
  sodium acetate. The solution is at pH = pKa = 4.75. What's the pH
  after addition of 0.01 mol/L HCl?

They don't write how much of the acid is added.

They go on stating that addition of x = 0.01 mol/L H+ results in pH = 4.75 - log[(1.01 mol/L) / (0.99 mol/L)] = 4.733.

That's all fine from the formalism. What's against my intuition is:

Why is it not required to state how much of the acid was added? Given the buffer solution, is the outcome of adding acid the same independent if I add a Liter of if I add a mL?


texts: Are coordination numbers of elements fixed?

texts: Can we say that the coordination number of a particular element is fixed? If not please give an example where an element exhibits variable coordination numbers.


texts: Why is there sulfur in black powder / gun powder?

texts:
Black powder is composed of charcoal, sulfur and a nitrate salt. The charcoal and sulfur serve as fuel and the nitrate is the oxidizing agent.
However, wouldn't it be cheaper to leave out the sulfur, thus having only charcoal as fuel?
Wikipedia says about this (emphasis added):

Black powder is a granular mixture of

[...]
sulfur (S), which, while also serving as a fuel, lowers the temperature required to ignite the mixture, thereby increasing the rate of combustion.

I guess after this initial research my question boils down to: Why is sulfur required as an ingredient in gun powder, and how does it lower the ignition temperature of the mixture?


texts: Accurate textbook about synthesis of (organophosphorus) chemical warfare agents

texts:
Lately I've been interested in the chemistry of nerve agents due to reading Patrick's Introduction to Medicinal Chemistry in which they were only briefly discussed. I bought the Handbook of Toxicology of Chemical Warfare Agents by Ramesh C. Gupta which appeared to me as a comprehensive work discussing the physical chemistry, biological action, history and legislation of a whole range of chemical agents (in particularly organophosphorus agents).

However it lacks experimental information (i.e. synthesis). I found a book that detailed (to the somewhat questionable extreme) on this information, having the rather obscure title The Preparatory Manual of Chemical Warfare Agents (it's a Google preview link, quite handy to see if a book is worth the money). Now since I'm not an expert in organophosphorus synthesis (else I wouldn't be interested in it, right?) I cannot fully appreciate the level of accurateness. And while you may argue that, since it's only of theoretical use to me, the level of accurateness is unimportant, I wouldn't really feel satisfied learning about something from a textbook that finally turns out to be based on completely wrong information. Because then what knowledge have I gained?

Now for the question: the book raised my suspicion because the author seems not to be related to any serious research unit or university for that matter. The poor lay-out, language, and somewhat too practical advice given here and there, screams Uncle Fester type bull shit book. So, is this book based on legitimate research? And if not, where can I read about (organophosphorus) chemical warfare agents synthesis from a reliable (preferentially written by well known and respected chemists) source, that goes into enough detail on a chemical level (and does not necessarily contain Uncle Fester type practical information in which I'm obviously not very interested)?


texts: What is the mechanism by which lactones are hydrolyzed during a Wolff-Kishner reaction?

texts:
I've been away from orgo for a few years but lately someone asked me a question about lactones during a Wolff-Kishner reduction.  I understand the basic mechanism of a Wolff-Kishner but I cannot figure out how a lactone gets hydrolyzed.  Can anyone help me with that step?

Here is a link to the basic mechanism that mentions lactones.


texts:
I'm looking for a database of very basic crystal models for all the various types - triclinic, monoclinic, orthorhombic, tetragonal, rhombohedral, hexagonal, and cubic.
A basic example would be a CAD file for a cube, to represent the cubic structure. I don't want like a packing model which shows the individual atoms because I'm trying to represent macroscopic crystals.
Any ideas where I could find what I'm looking for? Not a 3D graphic designer.


texts: Separation of alkylated 1,2,4-triazole in solution

texts:
I was looking into heterocyclic compounds and their alkylation (i.e. the regioselectivity of the alkylation of the compound).

People are able to give pretty exact numbers, for an experiment done in solution. Take, for example, 1,2,4-triazole, the alkylation can occur in one of two positions and papers state that the yield is about 9:1 in the 1 to 4 position.

How would one go about the separation of the solution to validate these claims? Or is there a method where this can be quantified in solution?


texts: Would combining essential oils and carrier oils be okay in terms of flash point?

texts:
With NO scientific, or chemical background, I am making my own beard oils. I found essential oil recipes online to mix with one or many carrier oils to make beard oil. I want to be original by going out on a limb and exploring other scents besides sandalwood, cedar, pine forest, bergamot, patchouli etc etc etc. I get so burned out seeing and smelling the same scents over and over.

With all of that out of the way, I want to combine some essential oils and carrier oils, and then mix in one of the three following oils to make an awesome scent like no other before this. The three following oils are from Crafter's Choice (if that matters.)
The three oils to choose from are

Butterscotch fragrance
Pink Cotton Candy fragrance
Double Bubble Gum (this one is actually a flavor)

I see on the bottles that these all have a flash-point. I'm guessing that has something to do with combustion at a known flash-point temp.

My main worry is, can I combine these flavor and fragrance oils with carrier oils, and or essential oils without worrying about some crazy Frankenstein mad scientist Yosemite Sam mishap on my face at some point in the day.

Would combining these oils be okay?


texts: Regioselectivity in opening of cationic three-membered rings

texts:
The mechanism of electrophilic addition on alkenes often involves an electrophile attacking the double bond and causing an electromeric shift of electrons. The electrophile then forms a bridged cation if possible.

The carbon on the left side has an alkyl group which shows inductive effect (and hyperconjugation effect) which increases the electron density on the left carbon. The right carbon is not bonded by any such alkyl group. Therefore, the electron density on the left carbon must be higher than that on the right carbon.

Why does the nucleophile $\ce{Nu}$ attack the carbon which has higher electron density?


texts: Keeping an open, partially empty soda bottle bubbly longer

texts:
I remember as a kid being able to get a little pump which you could screw onto a half empty soda bottle (I believe the bottles were glass at the time) to pump air into it to keep it fizzy for longer.  I surmised or was told that this worked by increasing the density of the air, thus making it harder for gas to leave the liquid and enter the air.

I now find myself with partially empty soda bottles.  Can I keep the fizz longer by squeezing the air out of the bottles and screwing on the lid?    (My guess would be that this would work if the compressed bottle is altered such that it does not try and reform back to its original round shape, but if it would pop back save for the lid being screwed on, I'm actually going to make it loose its fizz slightly faster ?)


texts: Does OH- attack carbonyl carbon in aldehyde during aldol reaction?

texts:
Why does $\ce {OH^-}$ not attack the carbonyl carbon in an aldehyde during the aldol reaction and instead, deprotonate the $\alpha$ hydrogen to form an enolate intermediate?

Also, why does the enolate intermediate attack the carbonyl carbon of another aldehyde once it is formed?


texts: What is the origin of the Quadratic factor in calculation of XRD peaks?

texts:
Whenever we are to calculate the d-spacing(for cubic system) in XRD peaks with reference to Quadratic Factors we do that with the help of the formula $$\frac{1}{d_{hkl}^2}=\frac{h^2+k^2+l^2}{a^2}.$$

Please tell me how we are arriving at this form and where from are we getting ${h^2+k^2+l^2}$ as a factor. I know that things are different for hexagonal. Would be happy if both are explained with more emphasis on the cubic one.


texts: Is there a porous thin material that will cool a stream of air passed through it to an even cooler temperature on the other side?

texts: Is there a porous thin material (e.g. filter paper, membrane) that will cool a stream of air passed through it to an even cooler temperature on the other side? If this material is absorbent, could there be a chemical absorbed into the material to facilitate the cooling?


texts:
I want to verify a thought I had about Gibbs free energy. In some ways, I'm actually wondering why we are using enthalpy instead of the internal energy $U$. Right now, I'm thinking that enthalpy is mostly useful because reactions are done at constant pressure (in an open beaker). If we were to do our reactions at constant volume, we would actually use Helmholtz's free energy instead of Gibbs. My logic:

The definition of internal energy:
$\Delta U = Q_\text{heat} - p\Delta V$

If we inject $Q_\text{heat}$ without holding the volume constant, we might change $U$ or $V$, which is a problem because we'll want to be able to describe our system as fully as possible. If we define the enthalpy:

$\Delta H = Q + V\Delta p$

Then, by keeping the pressure constant, we know that the heat added goes straight into this "enthalpy".

Afterwards, to know if a reaction is spontaneous, we need to see if the enthalpy-heat from a reaction overthrows the energy associated with the change in entropy.

Example: a molecule of two atoms wants to break apart. The bond has potential energy $Q_\text{heat} = \Delta H_0$ but it will increase the entropy by $Q_\text{entropy} = T \Delta S_0$. So, we check if:

$ Q_\text{heat} - Q_\text{entropy} > 0 $

$ \Delta H - T \Delta S > 0$

And thus Gibbs free energy was invented as:

$\Delta G = \Delta H - T \Delta S$

BUT, if we wanted to use a closed beaker, we would keep the internal energy U, and then to see if we had a spontaneous reaction, we would use Helmholtz's free energy:

$ \Delta F = \Delta U - T \Delta S $

I'm not sure about any of this and I'm mostly looking for confirmation/information of my logic. Please tell me if my intuition is wrong somewhere.


texts:
My mom while making Potato chips put some Baking Soda in Oil with it. Just curious to know, it was first time Baking Soda in Oil at that high temperature. Is it safe to eat?

Answer ASAP before my chips get cold.


texts: Why burn methane to CO2 for isotopic analyis?

texts:
I am wondering why mathane is burned to CO$_2$ for isotopic analysis, e.g with a mass spec?
I have looked into several text books, they all describe how to do it but not why.
Is it because of a interference on mass 16? Analysing methane it it is would give you also information about the D/H ratio. So why?


texts: Shelf life of 1,4-Butanediol, colloquially known as BD or BDO

texts: 1,4-Butanediol is a chemical cleaning solvent used for industrial purposes and a precursor of GHB. Companies now post the "official" shelf life as "2 years", but a 1997 publication by BASF said GBL had an "almost unlimited" shelf life if stored properly. Is there a reason 1,4-Butanediol would have a shorter shelf life than GBL? Would anyone know the real shelf-life if stored in sealed containers? How much would it chemically degrade after 10 or 20 years? Thanks!


texts: Can a strong nucleophile carry out an SN1 reaction?

texts: For example, if I take a tertiary halide in water + ethanol solution and add I- ions to it (which is a good nucleophile), then shouldn't the reaction be SN1; because SN2 is not possible as the substrate is tertiary. Please explain.


texts: What is the IUPAC nomenclature for the cyclic mono-alkene ions formed after proton or hydride abstraction?

texts:
In this blog post, Steven Bachrach discusses the (anti-)aromaticity or lack thereof in the homologous series of anionic and cationic cyclic mono-alkenes formed respectively by deprotonation and hydride abstraction at a vicinal carbon:

$~~~\small\unicode{x201c}$$\small\textit{KassCPcmpds.png}$$\small\unicode{x201d}\textit{ by }$$\small\textit{Steven Bachrach}$$\small\textit{ is licensed under }$$\small\textit{CC BY ND 3.0}$$\small .$

Bachrach uses the construction -enyl anion/cation to name these species, which seems sensible to me.  However, I also vaguely recall seeing generalized use of the -ide and -ium suffixes for singly charged anions and cations. For example, I know that $\ce{NO+}$ is nitrosonium, but I seem to be recalling incorrectly that $\ce{NO-}$ is nitroxide. $($The NIST Webbook page only calls $\ce{NO-}$ the nitric oxide anion, and the Wikipedia article on nitroxide-mediated radical polymerization is discussing radical alkyl N-oxides $(\ce{R2NO^\bullet})$, not $\ce{NO-}$.$)$ On the other hand, $\ce{R3CO-}$ ions are unequivocally alkoxides.

So: What are the systematic IUPAC names for these compounds?


texts:
How do I solve this-
Which diatomic gas would effuse at a rate that is 1.4 times faster than the rate at which so2(g) effuses at any given temperature? This is high school chemistry.

I did: (using graham's law) 1.4= sqroot of 64gmol-1 / xgmol-1 => 1.96= 64/x => 1.96x=64 => x=32.65g/mol. 32.65/2 (bc its a diatom) => 16.325g/mol which is close to oxygen.
At first, I found Urms of SO2 using 273k for T, 0.064kg for M and 8.314 for R, I got 326. Then multiplied that by 1.4 and got 456. Then I put 456/326= sqroot of 64gmol-1/ xgmol-1 and solved for x. I realized the 456/326 equaled 1.4, so I figured I didn't need to find Urms in the first place.


texts:
Is all unaltered diatomaceous earth (DE) food grade?

I am aware that all have not spent the money to have it certified and labeled as food grade, but I'm thinking that is just a way for the government to get more money and also have more control. All countries do not have an FDA, and therefore have no need to certify it, and have used it for thousands of years.

I just want to know the answer without somebody being afraid to say it is still food grade, labeled or not. I know the DE exposed to extreme heat is not safe and is for pool filters.


texts: How to extract force when the center of mass of molecules is put in the box in GROMACS?

texts:
To extract the force as in the title I used the gmx trjconv command like below.

gmx trjconv -f alad.trr -s alad.tpr -n alad.ndx -pbc mol -novel -force -o alad.gro

However, the force was not extracted in alad.gro file.
Of course, I got the coordinates and the force at equal intervals when getting the alad.trr file.

Another way, I used gmx traj command to get force.

gmx traj -f alad.trr -s alad.tpr -n alad.ndx -pbc -mol -ox coordi.xvg -of force.xvg

However, the force obtained from force.xvg didn't look like the value I wanted.

So, how do I get the force of molecules put in a single periodic box?


texts: Which d orbitals of sulfur take part in the pi bonds of SO3?

texts:
In $\ce{SO3}$, 2 $p\pi-d\pi$ bonds are present. But which $d$ orbitals of
  sulfur take part in these $\pi$ bonds?

The answer says $d_{xy}$ and $d_{yz}$. Someone also told me that crystal field theory supports it as while splitting $d_{x^2-y^2}$ and $d_{x^2}$ are raised in energy compared to the other 3, but that theory has nothing to do here.


texts: What caused this reaction between chlorine and brake fluid?

texts:
I recently saw a video on Facebook of a couple of people pouring brake fluid into a bottle containing pool chemicals (chlorine pellets, I believe). Now this was a rather strong exothermic reaction, resulting in a fire. At one point during the fire, fire appeared to be vapors burning under pressure (like a propane tank fire). I have included a link here. Unfortunately, it is not the original video that I watched.

My question here is what in the brake fluid is reacting so strongly with the chlorine? And what are the chemical products of this reaction (what's in the smoke)?


texts: What are the important implications to the field of chemistry, if any, of the recently confirmed hexavalent carbon species?

texts:
I’m struggling to understanding the true nature and implications of recent confirmations of the existence of stable species containing carbon atoms bound six (in another case 5) other carbon atoms. Is this really a breakthrough of science or one of semantics and scientific media hype? I've had a hard time understanding what I've read on this subject.

From Moritz Malischewski, Prof. Dr. K. Seppelt. Angew. Chem. Int. Ed. 2017, 56, 368-370, an open, online article:

  Herein we report the crystal structure of $\ce{C6(CH3)6^{2+} (SbF6^−)2⋅HSO3F}$,
  which revealed a non-classical structure for this labile species
  (Figure 1).

Figure 1.
Molecular structure of $\ce{C6(CH3)6^{2+} in C6(CH3)6^{2+} (SbF6^−)2⋅HSO3F}$, ellipsoids are shown at 50 % probability, C grey, H white; counteranions and co-crystallized $\ce{HSO3F}$ omitted for clarity.

Further discussion of this matter was also given in C&EN: "Six bonds to carbon: Confirmed", C&EN, Volume 94 Issue 49, p. 13  (abstract).

So, I understand how the octet rule is not actually violated. But then, can these molecules really contain carbons with 6 primarily covalently bound carbon neighbors? In what orbitals do all these electrons lie? Should we not be surprised as similar hypervalency occurs elsewhere on the periodic table?  Any clarification at all of these issues would be greatly appreciated.


texts: What is the reasoning behind the assumptions of Transition State Theory?

texts:
We were told in a first year introductory Thermodynamics and Kinetics lecture, and also from Wikipedia, that there are 3 main assumptions for the derivations used in Transition State Theory, but I'm not sure how or why they have been assumed?

Reactants are in constant equilibrium with the transition state structure.
The energy of the particles follow a Boltzmann distribution.
Once reactants become the transition state, the transition state structure does not collapse back to the reactants.

I'm concerned with 1. and 3. particularly, as it seems as though they contradict each other, because how can the reactants be in equilibrium with the TS, if the TS structure cannot revert back into reactants? How do we then utilise these assumptions, is it so that we can write
$$\ce{A + B <=> AB^‡ -> P}?$$


texts: Where to find a look-up table for mechanical properties of thermoplastics?

texts: Does anybody know of a good compilation, regarding mechanical properties of thermoplastics or in general polymers?


texts: Predict NMR spectra from the Mass Spectrometry

texts:
Imagine, you have a tissue and the Mass Spectrometry for it.
How would you get the corresponding NMR spectra knowing only the Mass Spec?
Is there is a special formula or a well-known technique?

I have an idea to build an ML model based on http://hmdb.ca metabolites data where you have those pairs (MS and NMR). But I worry it is completelly wrong.

Do you think is it a stupid idea?
If there is an easy way of converting MS -> NMR which everybody knows?

I'm sorry for a probably silly question, I came from mathematics.


texts:
It is known that allene (propadiene) $\ce{H2C=C=CH2}$ geometry is such that its hydrogen atoms are not in the same plane – do not form rectangle, but “extended tetrahedron”

I wonder if structurally analogous carbon dioxide $\ce{O=C=O}$ exhibit similar geometry, i.e. do its lone electron pair orbitals form extended tetrahedron as well (IUPAC officers probably would not like following structure diagram)

or are they in the same plane? And why?


texts: LIF spectrum with laser-coupled levels lines as the strongest

texts:
Why, if I excited the OH molecule Q-branch transition, my LIF spectrum (recorded during and after the laser pulse) does not result in only Q line being the most prominent, but also P and R lines with $\Delta J = \pm 1?$

How/why are these coupled?


texts: Is it possible (advisable?) to make a sealed tube by melting and twisting the end of a borosilicate test tube? One issue that I can think of is that the pressure might be too high if I then proceed to heat the tube. I thought that I could maybe connect the tube to a vacuum tube and heat it in the middle. Any experience with this?


texts:
Does there exist a mathematical model of isomerism? (a model which is capable of predicting, for given circumstances, the re-arrangement that is going to occur, e.g. Demjanov, Wagner-Meerwein etc.).

The goal is to:

understand how a geometrical structure of a molecule changes for isomers
understand under what conditions certain geometrical structure of one molecule is transformed into a different geometrical structure of an isomer
which geometrical isomer structures are impossible to exist


texts: Explanation for a basic decomposition of water experiment

texts:
My son is trying to write a conclusion for a basic decomposition of water experiment using a 9 V battery (with a test tube placed over each terminal) placed inside a salt water solution.  The results were: the tube over the negative terminal nearly completely filled with presumably hydrogen gas while the tube over the positive terminal only had a minute amount of presumably oxygen gas.
His textbook didn't explain these results, other than to hint at the fact that the results were due to there being twice as many hydrogen atoms in the product.  He has several questions that I cannot answer.

If the hydrogen and oxygen molecules take up the same amount of space, then why did the tube over the negative terminal have much more than twice the gas as the other one?
The atomic mass of oxygen is nearly 16 times that of hydrogen, so then even if there was twice as much hydrogen in the product, wouldn't the oxygen still take up more space?


texts:
As far as I get it, we did weigh one carbon (12,6-isotope) atom. Then we said that electrons have nearly zero weight and protons weight nearly the same as neutrons. Hence we took the weight of that one atom and divided it by twelve and this way we got the mass of a proton/neutron:

$w_\mathrm {n,p} = 1.6726 \cdot 10^{-24}\ \mathrm g$

Because that isn't easy to calculate with, we introduce a number which multiplied with the weight of a proton/neutron gives us one gram:

$N_\mathrm A = w_\mathrm {n,p}^{-1} = 1\ \mathrm{mol}$

So far so good. Now hydrogen weights 1 g/mol and carbon weights 12 g/mol. Two questions to that:

How did we actually measure the weight of one carbon atom in the first place?
Why is the molar mass not precisely 1 and 12?


texts: Can the structure of an azide ion contain a coordinate bond?

texts:
Can the structure of an azide ion ($\ce{N3-}$) be $\ce{N#N\bond{->}N^-}$?

I know the actual structure but was asking whether the single bond can be shifted to a N to make it a triple bond and a coordinate bond with other Nitrogen.

This is not a duplicate of Hybridization in azide ion? because I am asking whether it can have a coordinate bond or not while the other question asks what the hybridization of centre nitrogen in $\ce{N3-}$ is.


texts: How to calculate size of a specific cavity in a protein for every frame in trajectory file?

texts:
Here is the situation, I have trajecory file of a protein of interest. That protein has 2 main cavities that are participating in interraction with ligands or other proteins and also other cavities. Also residue numbers around this cavity are more or less known. I'm looking for a method or software to get volume of this cavities for every frame in trajectory.

I want to specify a cavity around a residue and  get output for this cavity. What I am looking for is something like this:

Frame Cavity volume
1 1500 A^3
2 1499 A^3
3 1499 A^3
4 1499 A^3
5 1498 A^3

I tried CASTp, it was okey for singe frame if wrote it as pdb but not promising for a 100ns trajectory.

Also tried CAVER. CAVER was able to open a trajectory file and calculate cavity volumes for the frame that I chose but it was not possible to calculate cavity volumes for all of the frames and get output from it.

If anyone has any suggestion I'll be greatful.


texts:
I just got in 10th grade and the first chapter in Chemistry in our school curriculum is Chemical Reactions and Equations

The chapter is littered with a lot of chemical reactions and their equations and most of the teachers I consult say that there is no alternative to revising them but I hate to blindly memorize stuff without knowing why it happens in that manner and not in some other way.

Is it really true that there is no other way than to memorize the equations?

If there is an alternative, please let me know.

And how can I predict the products of a chemical reaction if its reactants are given. Is it done by understanding the types of chemical reactions.

One of my teachers said that it could be done like this : If you're given two elements as reactants and you know that they will react, then you know that it is a combination reaction, you can figure out the chemical formula of the compound that those two elements will form on combination and then balance the equation. This works for simple reactions like Na + Cl $\longrightarrow$ NaCl or for some simple decomposition, displacement or double displacement reactions but what about complex reactions like this :

$2 Pb(NO_ 2)_3$ (s) $\longrightarrow$ $2PbO$ (s) + $4NO_2$ (g) + $O_2$ (g)

I can quite easily visualize a combination reaction as two elements sharing or losing or gaining electrons and combining to form a compound, but how do I visualize these types of reactions

I'm sorry if you find this question silly...

All answers are welcome

Thanks


texts: Equilibrium constant and thermodynamic relationship

texts:
Why is Equilibrium constant (Ratio of rate constants) considered as a thermodynamic quantity whereas the rate constant as kinetic quantity. Moreover why is extent of reaction also a thermodynamic quantity.?
Please explain briefly as I'm stuck.


texts:
Do atoms exist in hybrid form in nature, or do they form hybrid orbitals during molecule formation?

Take methane for example. Does carbon atom exist with $\ce{sp^3}$ hybrid orbitals in nature and then hydrogen forms bond with only $\ce{sp^3}$ carbon atoms?
Or does carbon form $\ce{sp^3}$ hybrid orbitals during the formation of $\ce{CH4}$?


texts:
Being new to chemistry, there may ought to be some properties I couldn't understand fully. One of them being cyclic compounds.

One particular question about this is, whether these cyclic compounds, say benzene rings 'link' in-between one another like a chain. Having one molecule chain of one benzene molecule, go through the center of another, before closing back up as a ring.

Unfortunately, I couldn't seem to find any term describing it for further research.

This may be a stupid question or have been asked before, but since I couldn't find my answer anywhere, hopefully someone may either point out why wouldn't this exist in any case or redirect me to an answer.


texts:
I'm struggling to interpret enthalpy of mixing data. Given this plot,  from this paper, say I want to calculate the heat released from mixing 0.29 mol of 7.7% ethanol with 0.71 mol of 28.7% ethanol to get 1 mol of 22.6% ethanol.

Is it correct to say $\Delta h_m = 753 - (0.29*605 + 0.71*672) = 100 J/mol$?

Or, in other words, can I subtract the molar weighted enthalpies of mixing at the initial states from the enthalpy of mixing at the final state to get the change of enthalpy of mixing from that process?

It seems trivial, but something about it feels weird.


texts: Can alkyl-substituted phenols be reduced to alkyl-substituted benzenes by zinc dust?

texts: I know that phenol can be reduced to benzene by distilling it with zinc dust. But I want to know if that concept can be expanded. E.g., take chavicol or 4-(prop-2-en-1-yl)phenol; could you still remove the hydroxy group by distilling it with zinc dust?


texts: Why Fe(III) can't coordinate with O2 in methemoglobin

texts:
I know methemoglobin's heme group has a change on its shape, what makes oxygen unable to coordinate, but... What causes that change? Does the electronic structure of $\ce{Fe(III)}$ matter or it's only a charge/radius conseqüence?

My solution is the following:

As $\ce{Fe(III)}$ is a hard Lewis acid, it needs hard Lewis bases, such as $\ce{H2O}$ and not $\ce{O2}$.   Furthermore, the His $\ce{F8 }$ proximal's imidazole bond with $\ce{ Fe }$ becomes stronger, as it's relation charge/radius is bigger in $\ce{ Fe(III)}$ than in $\ce{ Fe(II)}$, which causes a torsion of the heme group. Is that right?


texts: What is the specific functional group in MDMA that caused addictive effect on user?

texts: First of all, the reason I'm asking this is because I'd just done an experiment detecting MDMA in a urine sample with GC-MS for my internship program. I'm having difficulties figuring the functional group which cause the said effect as in my question. I've read two journal Shulgin and Nichols and I thought they explored more of the hallucinogen effect from N-methylation.


texts: dU/dV in van der Waals equation of state derivation

texts:
Previous, I proved that

$$\frac{T_2}{T_1}^{C_V/(C_p-C_V)}=\frac{V_1}{V_2}$$

I've been asked to derive a similar expression for a gas that obeys the equation of state

$$p=\frac{RT}{(\overline{V}-b)}$$

I started with the first law and made the assumption that

$$\mathrm dU=\frac{\partial{U}}{\partial{V}} + \frac{\partial{U}}{\partial{T}}  + \frac{\partial{U}}{\partial{n}}$$

I know that for an ideal gas, we can say that $\frac{\partial{U}}{\partial{V}}$ goes to zero... but would this also be true for my given equation of state?

Making that assumption, I ended up with something like

$$\frac{T_2}{T_1}^{\overline{C_V(t)}}=\frac{\overline{V_1}-b}{\overline{V_2}-b}$$

Any suggestions would be immensely appreciated.


texts:
The protons alpha to the oxygen in methyl propionate are more shielded than their corresponding protons in ethyl propionate.

.

We can see from the NMR data that this is the case as well.

My TA says this is due to the inductively withdrawing effect of the extra carbon in ethyl propionate.

However, this strikes me as blatantly wrong. The carbon should be inductively donating ... I don't see how it pulls electron density away from the specified hydrogens.


texts: What is the definition of organic compounds?

texts:
According to the definition of organic compounds on Wikipedia:

  An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon.

Carbonates, simple oxides of carbon, and cyanide molecules do have carbon, but they are not regarded as organic.  The same Wikipedia article on organic compounds reads:

  The modern meaning of "organic compound" is any one of them that contains a significant amount of carbon.

The current main definition for organic compounds doesn't fit for carbonates, simple oxides of carbon, steel, etc. So, what should be the redefined definition for organic compounds?


texts: When an aqueous extract of a substance is said to be administered at a certain quantity, is the quoted mass analogous to one as original substance?

texts:
I'm trying to read studies about the possible toxicity of the leaves of some plant often said to possess positive medicinal properties.
In the studies, performed on rats, it is usually said that an aqueous and/or ethanol extract of the plant was administered at $x \ \pu{mg/kg}$ of mice mass, and from that data possible lethal or detrimental dose is extrapolated.
What I don't understand and is not explained in the texts (therefore I assume there is standard practice I'm not aware of) is how concentrated is $\pu{1 g}$ of the aqueous extract compared to $\pu{1 g}$ of the original fresh leaves. For example, one study simply states, referring to the administered aqueous extract: "The $\mathrm{LD_{50}}$ was estimated to be $\pu{1585 mg/kg}$." Should one infer that the amount of chemical substances administered in this scenario is equal to that found in $\pu{1,585 mg}$ of fresh leaves? Or is it possibly less/more concentrated?


texts: How to effectively wash the precipitate or crystals on the filter and why?

texts:
My lab manual says that the precipitation on filter should be washed with a few small portions of the washing liquid. Why can't I just completely fill the filter funnel with the solvent instead of steadily add new tiny portions in it?

Also, how effective this washing process is? How many times should I wash the precipitation before it's completely free from impurities?

What filter funnel of what diameter of the paper filter should I use? Isn't the biggest one the is also the most effective?

Finally, why do I have to study limits when I want to become a chemist, not a mathematician?


texts: How to refer to this method of mixing solids?

texts:
The steps of this process are:

Fill a container with water (or other solvent)
Add mixants (is that the right word?) the container
Stir until all mixants are dissolved/suspended
Boil off the water (or other solvent)

The substances do not end up chemically reacting during this process. A real-world application of this is in small-scale manufacture of Rocket Candy, where this is used to mix KNO3 and Sucrose so the mixture can later be ignited and will burn more smoothly. Another example is making a cake - all the ingredients end up dissolved or suspended in the batter to mix them, and then the water is boiled off during baking. (Yes, there are also a lot of other things that happen during cake-making.)

What is the name of this process, if it has one? If not, what is a succinct way to describe it or state that this is what is used?


texts: Use of osmosis to measure molecular weight of macromolecules

texts:
I found a question in a biochemistry book.

How can osmosis be used to measure molecular weight of macromolecules? Is it applied practically?

A general answer without the usage of many technical terms would be most suitable for me.


texts: Molecular similarity using Tanimoto coefficient

texts:
I'm trying to use a method for evaluating similarity of molecules. I have seen many publications in the machine learning community have used Tanimoto coefficient. However, when I read about it, it states that this is a measure of similarity for molecular fingerprint representation.

I was wondering if this means that the measure of distance is not for the molecule itself but for its representation?
If so, is there a measure that compares two molecules based off of their inherent structure rather than the particular representation of choice?

Also, any other suggestions on the choice of measure would be appreciated.


texts: What are the additional chemicals required to make polyurethane foam more viscoelastic?

texts: I am currently experimenting with polyurethane forms for a science and research project I am working on. I need to make the polyurethane foam more viscoelastic, almost like memory foam. I am unable to proceed and would be great if I could get some guidance.


texts:
I think the question needs no elaboration. Why are salts containing Group 1A cations extremely soluble in water?

I speculate that the reason involves the low charge density of those ions in a given period. Thus, they make better ion-dipole bonds with water molecules than other cations. But the sizes of the Group 1A metals vary, so an argument based on charge density fails as a generalization.


texts: Maintaining a 40% CO₂ aqueous environment?

texts:
I wish to grow algae in a 40% $\ce{CO2}$ (water under air with 40% $\ce{CO2}$ content) aqueous environment.

Simple DIY methods are available, but they are generally unreliable (For more info on DIY read here) because they rely on a pH/KH chart.

Atmospheric $\ce{CO2}$ levels are measured based on IR absorbency. However, such measurements are difficult and "complicated by the temperature signal generated by carbon dioxide as well as by the signatures of ozone and water vapor."

Is there a reliable way to measure the $\ce{CO2}$ concentration that is relatively inexpensive (under $1,000)? Is the drop checker method reliable?


texts: What is the multiplicity of this signal in the ¹H NMR of glutamine in D₂O

texts: The 2 Hydrogens near the carbonyl (the lower 2 $\ce{H}$s are not bonded to the nitrogen) should be the most deshielded so I think they appear as the rightmost peak in the NMR.  Are these 2 $\ce{H}$s a doublet of doublets?  I think this because they are split by 2 different $\ce{H}$s.


texts:
1 amu (atomic mass unit) is defined as the one twelfth of the mass of a carbon-12 atom. The mole is defined as the number of carbon-12 atom in 12 g of carbon-12. In other words,

$$\require{cancel} 1 \textbf{ mole} = \dfrac{12 \textbf{ g}}{m(^{12}C)} = \dfrac{\cancel{12} \textbf{ g}}{\cancel{12} \textbf{ amu}} = \dfrac{\textbf{ g}}{\textbf{ amu}} $$

I believe that the 12 g were chosen so that the mole could exacly express the ratio between the g and amu.

Consider now this alternative definition : the amu is defined as the exact mass of a proton and the mole is exact ratio between the g and the amu. Wouldn't it be simpler this way?

What are the advantages of one definition over the other? Is there any reason we would want to keep the former? Why scientists decided to define the mole like that and not pick a simpler definition like the one I proposed?


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I understand that it is possible to cool a liquid past its freezing point, and still maintain its liquid state because crystallisation would not happen in the absence of a seed crystal.

My question, was marked as a duplicate and I was linked to to Can all substances be supercooled?

One of the answers over there does address my question but only in part.
Here's what it says:

  "However, when there is only liquid present, you will first have to form a small crystal nucleus which is not as stable as the bulk solid i.e. has a higher free energy. This is basically a kinetic barrier which prevents forming the solid.
  The formation energy of such a nucleus will depend on the interfacial energy of the crystal-liquid system. In a substance where this interfacial free energy is very little there won't be too much supercooling."

My question still remains. Why is the lack of a nucleus a kinetic barrier to the formation of a bulk solid? If you continue past the glass transition temperature, we form an amorphous solid anyway. How do the mechanics of vitrification and crystallisation differ in this regard?


texts: Dubowski’s Formula vs Henry's law applied to alcohol sensor 'calibration'

texts:
I'm working with some hobby-level gas sensors and I've run across a "calibration" system I don't understand. A general description of this kind of gas sensor is described a bit more in this question and also here. They have some selectivity between gases, but anything that will react with atomic oxygen at elevated temperature in the presence of a catalyst ($\ce{CO}$, $\ce{H2}$, $\ce{CH4}$, etc.) will register.
Since I don't want to mess with explosive gases, the alcohol sensor is a convenient place to begin. Many hobbyists become voluntary test subjects, and heroically subject themselves to alcohol, then breath on the sensors. Since I'm not so brave, I thought I'd try the recommended calibration test setup below. I'm not interested in doing a careful calibration, but just get some kind of ballpark quantitative agreement.
Henry's law suggests a proportionality between the concentration of a dissolved gas and the partial pressure of the gas above the liquid, and the van 't Hoff equation provides for a temperature dependence within some limited range of variation. However it's of the form $exp(\frac{1}{T}-\frac{1}{T_0})$ and the equation shown below is only a straight exponential of temperature.
This is described more thoroughly in this excellent answer:

Henry's law works for small concentrations of ideal mixtures at equilibrium. Henry's Law constant varies with temperature according to the Van't Hoff equation:

$$
k(T)=k(T_0)exp\left[-C\left(\frac{1}{T}-\frac{1}{T_0}\right)\right]
$$

Here $C$ is a constant related to the enthalpy of solvation for each gas, and $T_0$ represents the standard state, T = 298 K and 1 atm.

Question: Is Dubowski’s formula just a further approximation, or does this method  contain something new and/or different that I should be paying attention to?

below: Screenshot from Adafruit's AN4 Using MiCS Sensors for Alcohol Detection.pdf


texts: Are `dTDP-4-dehydro-6-deoxy-alpha-D-galactose` and `dTDP-4-keto-6-deoxy-D-glucose` the same thing?

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Are dTDP-4-dehydro-6-deoxy-alpha-D-galactose and dTDP-4-keto-6-deoxy-D-glucose the same thing?
I am looking for the function of this enzyme in uniprot. It says

Catalyzes the synthesis of dTDP-4-amino-4,6-dideoxy-D-galactose (dTDP-Fuc4N) from dTDP-4-keto-6-deoxy-D-glucose (dTDP-D-Glc4O) and L-glutamate.
dTDP-4-amino-4,6-dideoxy-alpha-D-galactose + 2-oxoglutarate = dTDP-4-dehydro-6-deoxy-alpha-D-galactose + L-glutamate.

Note that glucose in the first line and galactose in the second line.
Or it is a typo there?