texts: Is it possible to melt diamonds into a liquid? I mean if you heat diamond at open air it will start to burn around 700 degrees Celsius, reacting with oxygen to produce carbon dioxide gas. In the absence of oxygen it will transform into graphite, a more stable form of carbon, long before turning into graphite. My question is, is it possible to melt diamonds into liquid? If so, then, how? If not, then why?


texts: Decomposition of acetonide protecting group in chloroform

texts:
Today I purified my compound containing an acetonide protected diol. I took an NMR sample and it looked great, but because I have only little amount of the compound, I put the sample back into the flask and evaporated the $\ce{CDCl3}$.

In a while, the solution turned from yellow to brown, so I took another NMR and it looked a little bit more messy and the $\ce{CH3}$ signals from acetonide group had decreased intensity (integral from 6 to around 4.5).

Is it possible that the $\ce{CDCl3}$ is so acidic it causes acetonide removal? The compound survived silica chromatography. Have you ever experienced something similar?


texts:
The question involves the addition of $\pu{0.15 g}$ of an already prepared sample of sodium peroxoborate which is added to $\pu{100 mL}$ of $\pu{1 M}$ $\ce{H2SO4}$ and $\pu{2 g}$ of $\ce{KI}$. The solution is left to stand for 10 minutes and is then titrated against standardized sodium thiosulfate. Starch indicator was used and a titration figure of $\pu{17.1 mL}$  was obtained. Find the moles of sodium peroxoborate.

Sodium peroxoborate, sulfuric acid and potassium iodide react as follows:

$$\ce{Na2[B2(OH)4(O2)2] + 4 KI + 3 H2SO4 -> Na2SO4 + 2 K2SO4 + B2O3 + 5 H2O + 2 I2}$$
Iodide reacts with thiosulfate as follows :

$$\ce{I2 + 2 [S2O3]^2- -> 2 I- + [S4O6]^2-}$$

I'm not sure how to use the titration value to find the result of this answer. I'm not looking for the solution I just need a point in the direction that will help me at least get a start on the problem.

What about this:

$$2 \, \text{mol} \, \ce{S2O3 ->} 1 \, \text{mol}  \, \ce{I}$$

when we made the sodium thiosulfate I calculated the moles to be $0.096 \, \text{mol/L}$. Hence

$$0.096 \, \text{mol/L} \, \, \ce{S2O3->} 0.048 \, \text{mol/L}  \, \, \ce{I}$$.

the relationship between iodine and peroxoborate is as follows:

$$4 \, \text{mol} \, \ce{I->} 1 \, \text{mol}  \, \ce{[B_2(O2)2(OH)4]}$$

Hence

$$0.048 \, \text{mol/L} \, \, \ce{I->} 0.012 \, \text{mol/L}  \, \, \ce{[B_2(O2)2(OH)4]}$$.

But I didn't use the titration value of thiosulfate in this solution?


texts: How does a redox reaction between ClO- and Br- take place?

texts:
How does a redox reaction between $\ce{NaClO}$ and $\ce{KBr}$ take place?

will bromide be oxidised to bromine?

$\ce{2 Br- + CIO- +  H2O  ->  Cl- + 2 OH- +  Br2}$

or will bromide be oxidised to $\ce{BrO-}$?

$\ce{Br- + CIO-   ->  BrO- + Cl-}$


texts: I was given a document on liquid crystals by my university , it does include subtopics on blue phases and twist grain boundary phases, but not much on frustrated phases.


texts: Can Molisch test be used to separate monosaccharides from polysaccharides?

texts: Do the results of Molisch test on monosaccharides have any differences with when it's done to disaccharides or polysaccharides?


texts:
Much time has passed since my basic chemistry and I am trying to determine if an awaruite mine proposed by FPX Nickel Corp ("FPX") might serve as feed-stock to nickel sulfate for battery production.

Chemically, this is as far as I got and I am not at all certain if the typical counter-current decantation ("CCD") would remove the unwanted iron.  Neither do I know anything about how to hydrate $\ce{NiSO4}$ into battery grade hexahydrate form $\ce{NiSO4 * 6 H2O}$.

Here is the proposition (source: this is a commercial site):

  Awaruite comes in 2 forms: $\ce{Ni2Fe}$ and $\ce{Ni3Fe}$. Sulfuric acid is $\ce{H2SO4}$.
  \begin{align}
\ce{Ni2Fe + 3 H2SO4 &-> 2 NiSO4 + FeSO4 + 3 H2} \\
\ce{Ni3Fe + 4 H2SO4 &-> 3 NiSO4 + FeSO4 + 4 H2}
\end{align}
  Then precipitate the iron sulfate to get rid of it and add water to hydrate the nickel sulfate:
  $$\ce{NiSO4 + 6 H2O -> NiSO4(H2O)6}$$

I think this is the form needed for battery production. I think the counter-current decantation (CCD) is the process of precipitating the iron sulfate.


texts: E2 towards secondary over tertiary and primary beta-carbons

texts:
I would like to convert this tertiary bromoalkane to this trisubstituted alkene via E2

Theoretically, using a strong base (NaOH) would result in the formation of the Zaistev product (tetrasubstituted) as major, which I do not want.

If instead I use a sterically hindered base such as t-BuOK I would get the Hofmann product (disubstituted), which I also do not want.

What would I need to use in order to obtain the 'intermediate' trisubstituted alkene? Would it work if I just used a base that's less sterically hindered than t-BuOK but still blocks formation of Zaistev? Like NaOEt for example?

Thank you


texts: Will propane liquefy under these conditions?

texts: Consider a 1:1 mixture of propane and nitrogen at $60°\mathrm{F}$ and $75\:\mathrm{psi}$. Will the propane liquefy if pressure is increased to $200\:\mathrm{psi}$? I am experimenting in the oilfield with a shallow heavy oil lease.


texts: How to find the normal boiling temperature if vapor pressure at any temperature is the only thing that can be usable?

texts:
Here is my program for calculating the vapor pressure of the Organic Chemicals using Antoine's Equation:
def Psat_Antoine(temp,A,B,C):
    return numpy.exp(A-B/(temp+C))

A_Actn, B_Actn, C_Actn = 14.31451662590449, 2756.0411263712826, 228.03915724014055
A_Mthnl, B_Mthnl, C_Mthnl = 16.572099163421438, 3634.3383035408656, 239.33433646852495

temp = input("Give temperature in C:")
vapor_pressure_actn = Psat_Antoine(temp, A_Actn, B_Actn, C_Actn)
vapor_pressure_mthnl = Psat_Antoine(temp, A_Mthnl, B_Mthnl, C_Mthnl)

I want to calculate the normal boiling temperature of the Acetone, Methanol, or any kind of chemical that I know A, B, C constants. But there is a challenge, I can't use if, while or for loop. I have to use some kind of equation that calculates the normal boiling temperature of Acetone, Methanol etc. And the Psat_Antoine() function is the only thing that I can use to figure out the normal boiling temperature. Is it possible to write such program?
Thanks for the help.


texts: Why is it necessary to avoid even traces of moisture from a Grignard reagent?

texts: This fact was written in my text book. I wonder why that should be so.


texts: What exactly are the frontier orbitals in diradical species like O2?

texts:
I read about frontier orbitals, namely HOMO, LUMO. But what's exactly HOMO/LUMO? I know HOMO stands for highest occupied molecular orbital and LUMO stands for lowest unoccupied molecular orbital.

But I am not getting which orbital is to be tagged as HOMO, and which as LUMO. Consider the example of $\ce{O2}$, highest occupied MO is $\pi^*_\mathrm{2p}$ and lowest unoccupied MO is also $\pi^*_\mathrm{2p}$. Which orbital is HOMO/LUMO? Is $\pi_\mathrm{2p}$ the HOMO and $\pi^*_\mathrm{2p}$ the LUMO? If so, why? There is a similar case with $\ce{B2}$.


texts:
I recently been studying different radioactive elements. The most difficult part is find the output of these elements in the form of kWh.

Is there a database or chart of these elements' output?

And most importantly does anyone know the kWh of $1~ kg$ of $\ce{^99Tc}$?


texts: Basicity of nitrogen in amide versus basicity of nitrogen in aniline

texts:
I was wondering that how can we compare the basicity of nitrogen in amide to the nitrogen in aniline as in both structures the lone pair on nitrogen is in conjugation as shown below,

Can someone help me?


texts: What does the crystal field splitting diagram for trigonal planar complexes look like?

texts:
For a trigonal planar complex (e.g. $\ce{[AgCl_3]^2-}$):

According to this image (source):

The $x^2 - y^2$ and $xy$ orbitals are on the same energy level. However, assuming that one of the $\ce{Cl}$ ligands lies on the $y$ axis (or the $x$ axis), wouldn't the $x^2 - y^2$ orbital be higher in energy? Thanks in advance.


texts:
I know that $\ce{CO_2}$ and $\ce{O_2}$ are slightly soluble in water ($\ce{H_2O}$)

In my understanding, when carbon dioxide dissolves in water, it will react to form carbonic acid just like the equation below.

$\ce{H2O + CO2 -> H2CO3}$

So, my problem now is, I can't find the equation for oxygen.
 Will they form hydroxide ions or something else?


texts: Will the water at the bottom of the tube boil at the same temperature as the water at the top of the tube?

texts:
Consider a long, vertical tube of water, as shown below:

Where $P_\mathrm{atm}$ is the atmospheric pressure and $P_\mathrm{bottom}$ is the pressure at the bottom of the tube.

The tube is long enough such that $P_\mathrm{atm}$ is much less than $P_\mathrm{bottom}$.

It is known that water at the surface (top of the tube) will boil at a temperature such that the water's vapor pressure equals $P_\mathrm{atm}$. Let's call this temperature $T$. For example, $T=100~^\circ\mathrm{C}$ when $P_\mathrm{atm}$ is about $1\mathrm~{atm}.

Question: At what temperature will the water at the bottom boil? Will it be higher than $T$ or equal to $T$? Why?

References, if available, would also be greatly appreciated.


texts: Electron Ionization and the Franck-Condon Diagram: vibrationally excited and vibrationally ground states

texts:
I am currently studying Mass Spectrometry: A Textbook, third edition, by Jürgen H. Gross. On page 41, the author says the following:

  As explained by the Franck-Condon diagram, hardly any molecular ions will be generated in their vibrational ground state. Instead, the majority of the ions created by EI is vibrationally excited and many of them are well above the dissociation energy level, the source of this energy being the 70 eV electrons.

On page 37, the author presented the following Franck-Condon diagram:

In this diagram, the energy is plotted on the ordinate, and the bond length is plotted on the abscissa.

My understanding is that the vertical transitions represent the electron ionization of the neutral $M$.

Following this diagram, on page 38 the author said the following:

  The counterpart of the vertical ionization is a process where ionization of the neutral in its vibrational ground state would yield the radical ion also in its vibrational ground state, i.e., the $(0 \leftarrow 0)$ transition. This is termed adiabatic ionization and should be represented by a diagonal line in the diagram. The difference $IE_{\text{vert}} - IE_{\text{as}}$ can lead to errors in ionization energies in the order of 0.1 - 0.7 eV.

So, If i'm correctly interpreting the description below the Franck-Condon diagram, the only way for the molecular ions to be generated in their vibrationally ground state is if the bond lengths of the molecular ion in its ground state somehow end up being larger than the bond lengths of the molecular ion in its vibrationally excited state?

If my interpretation so far is correct, then two related questions immediately follow:

Why is it unusual (as it seems to be implicitly implied) that the bond lengths of the molecular ion in its ground state somehow end up being larger than the bond lengths of the molecular ion in its vibrationally excited state?
How does a situation arise where the bond lengths between such molecular ions differ so significantly that some end up in a vibrationally excited state and others in a vibrationally ground state? (If I had to give an educated guess, I would say that this is just due to random or non-primary factors.)

I'm studying this from a non-chemistry background, so I'd appreciate it if people would please take the time to explain this in a more novice-friendly way.


texts: Is there an anisotropy factor (g factor) for TDDFT Abs and CD calculations?

texts:
Experimentally, anisotropy factor is calculated by dividing the CD spectra by the absorbance spectra multiplying by a factor of 32980 (in order to get a nondimensional quantity)

Theoretical calculations can be performed via TDDFT to obtain rotatory and oscillatory strengths, obtaining excitations for each case and adjusting, for each excitation, a curve, obtaining then the "theoretical absorbance/CD spectra".

How can then we define a theoretical anisotropy factor, does it have sense?
Should another calculation be performed?

Would you divide both adjusted curves or divide the corresponding excitations, adjusting a new set of curves to what you get?

Any clues?


texts: Why are secondary standard solutions used in titrations? Why don't we always use primary standard solutions?


texts: Difference between an absorbance, emission, and excitation spectrum for uv-visible spectroscopy

texts:
From the list below, circle the wavelength that would be the best setting for the UV-visible spectrophotometer used to determine the FITC concentration in the sample.
\begin{array} {}
\mathrm{wavelengths:} & \pu{400 nm}& \pu{450 nm}& \pu{500 nm}&\pu{550 nm} &\pu{600 nm}
\end{array}

The exam paper answer is $\pu{500 nm}$, because we need the wavelength of "maximum absorbance." But this graph shows two curves, and the absorbance curve is omitted.
But what is the difference between an emission, absorbance, and an excitation spectrum? What are they measuring? How do you interpret/read these graphs - those with multiple curves.


texts: How to calculate the mass of hydrogen in a borane sample?

texts:
In a $\pu{45.9 g}$ sample of borane, a compound containing only boron and hydrogen, that's $85.63\%$ boron, what is the mass of hydrogen in this sample?

I was just going to take $\pu{45.9 g}$ and multiply by $0.1437$ to get the mass of hydrogen, but I don't think it works that way because they don't equally contribute to the mass of the compound. Then I thought, maybe I should consider the molar masses of both atoms, hydrogen being $\pu{1.008 g mol-1}$ and boron being $\pu{10.811 g mol-1}$. I am stuck at this point. How to solve the question.


texts: What is the total number of isomers, considering both structural and stereoisomers of cyclic ethers with the molecular formula C4H8O?

texts:
According to me, it should be 11 and this is how I have worked out as shown in the attached diagram.

However, I am not sure whether all these 11 isomers can be considered as those belonging to cyclic ether.

I had erroneously uploaded incorrect diagram earlier. Now I have uploaded the correct diagram. My specific query is whether the 11th Isomer shown in this diagram, wherein Oxygen is not part of the ring, can be considered as Cyclic Ether.


texts: How can we prove the inequality TdS > dU + pdV?

texts:
I know that for reversible process
$$T\,\mathrm dS = \mathrm dU + p\,\mathrm dV,$$
but since all the terms in the given equation are state variables so the above equation should also be true for irreversible processes but in my textbook for irreversible process the inequality is used for irreversible process.


texts: How to find the molecular weight of a given gas based on its density?

texts:
The density of a gas $\ce{X}$ is $10$ times that of hydrogen. In that case, what is the molecular weight of gas $\ce{X}$?

Well what I've done up to now is this:

The molecular mass of hydrogen is $M(\ce{H2})=2$, the density of hydrogen is $\rho(\ce{H2})= \pu{0.089 kg/m3}$.
Assuming that equal volumes $V$ of both gases are taken, the mass of hydrogen $m(\ce{H2})= (0.089 \cdot v) \pu{kg}$ and the mass of the unknown gas $m(\ce{X}) = (0.89 \cdot v) \pu{kg}$.

Although this hasn't really gotten me anywhere. How will it be done?


texts: Can sodium dithionite reduce the nitro group of 2-nitrobenzoic acid?

texts:
Can sodium dithionite reduce o-nitrobenzoic acid to anthranilic acid under basic conditions with mild reflux?

If so, how could I separate anthranilic acid from the reaction mixture?


texts: Why does hydroxide attack the carbon atom of methyl iodide (in an Sn2 reaction)?

texts: As the electronegativity difference between carbon and iodine is negligible, why does $\ce{OH-}$ attack the carbon atom (in an $\mathrm{S_N2}$ mechanism) even though carbon doesn't seem to be electrophilic? (Since the $\ce{C-I}$ bond is not polar enough to give a sufficiently positive partial charge on carbon)


texts:
During water electrolysis, the electrochemical reaction on the cathode side can be expressed as protons combined with electrons to form hydrogen. I believe this electrochemical reaction is a heat release process, but I don't know the reason.

Why protons combined with electrons will release heat?

It will be better if you could provide some references.


texts: In my electrolysis experiment, I used a 9 volt battery, 1:100 mL baking soda:distilled water, and stainless steel electrodes. I noticed that the anode degraded faster than the cathode. Out of curiosity, is there a phenomena to explain this?


texts: Why do electrons in sigma bonds have zero orbital angular momentum about the internuclear axis?

texts:
As per the title, why do electrons in σ-bonds have zero orbital angular momentum about the internuclear axis?

As far as I know, the outermost electrons participate in bonding. Suppose that the 3p electrons are the outermost and form a σ-bond. Initially, their individual orbital angular momenta are

$$|\vec{l}| = \sqrt{l(l+1)}\hbar = \sqrt{3}\hbar$$

since they have the orbital angular momentum quantum number $l = 1$. How can this become zero after forming a σ-bond?


texts: Proper explanation for depression of freezing point

texts:
Why does depression of freezing point takes place if a non-volatile solute is added to the solution?

Depression of freezing point


texts: I often see $U$ or even $\Delta U$ being the symbol for lattice energy. Why is that? Does it refer to internal energy?


texts: Is Gibbs energy change during osmosis positive? If so then why is it spontaneous?

texts:
For ideal solution, μA=μA* +RT
  lnxA

ln function is an increasing function, means that the higher the xA the higher the μA......(1)

Now consider osmosis. From Atkins' Physical Chemistry Ninth Edition, page 173,

  osmotic pressure, π, is the pressure that must be applied to the solution
  to stop the influx of solvent (into solution across a semi-permeable
  membrane).

Here is my interpretation and thought process:

Had you not exerted π on solution, the μ(solution)< μ(solvent) based on (1) because lnxA is negative for xA<1, so by Second Law, the osmosis is spontaneous and solvent should move from pure solvent (high μ) to solution (low μ). Sounds right.

However, during this process, μ(pure solvent) unchanged (μ is intensive, not affected by amount) but μ(solution) increases due to dilution. Based on (1), for the solution, since xA increases μ(solution) must also increase. Although the process stops when μ(solution)=μ(pure solvent), the effect is that μ increases. μ increases would in turn imply ΔG>0 which means non-spontaneous, but as far as I know osmosis is spontaneous, so where is my misconception?


texts: Can we use the uniform circular motion formulae to calculate the velocity  of an electron along with the formula of radius of nth Bohr orbit? And using that can we calculate the kinetic energy of an electron?


texts: What method is used to discover oxidation state of drug binding cysteine residue?

texts:
I was reading this article and found this sentence:

  KC group found that some cancer cells became resistant to
  Boehringer Ingelheim’s covalent TKI afatinib (Giotrif) due to the
  oxidation of its target cysteine in EGFR

What would be the chemical method to discover that especially the target cysteine is oxidized? Can it be done with NMR or spectroscopy?


texts: Will potassium permanganate react with ferric chloride?

texts:
I came across a question :

Which of the following compound does not decolourise an acidified solution of $\ce{KMnO4}$?

Answer was:

 $\ce{FeCl3}$

After doing a bit of research I found that $\ce{KMnO4}$ oxidises $\ce{HCl}$ to $\ce{Cl2}$.
I doubt whether $\ce{KMnO4}$ would also oxidise chloride ions in case of acidified solution of $\ce{FeCl3}$.
I know that the ferric ion cannot be oxidised further.


texts: How many electrons are transferred in this redox reaction?

texts:
I have the following reaction:

$$\ce{CH_4 (g) + 2O_2 (g) \rightarrow CO_2 (g) + 2H_2 O(l)}$$

How do I determine how many electrons are transferred in this reaction? More specifically, I need to know the value of $v_e$ which I am supposed to plug into the Nernst equation, which my textbook explains as the coefficient of the number of electrons transferred in each half-reaction. How does one go about splitting this into two half-reactions?


texts:
I am trying to figure out the NMR spectra of F3P-BH3
I am solving this out using 2nI+1 rule.  IP = 1/2 and IB = 3/2
Hence for this compound,

(2nIP+1)(2nIB+1) = (2x1X1/2+1)(2X1X3/2+1) =
(2)(4) = 8 lines (quadraplet of doublet)

This is what I came up with, it would be great if you could correct me if I'm wrong. Trying to solve few problems before the exam =)


texts: Cathode gained mass in zinc electrolysis

texts:
I performed an electrolysis of zinc, using two zinc electrodes and a zinc nitrate solution. However, after leaving the electrolysis to run for 30 min, at about 0.4 A and 6 V, I discovered that the cathode gained more mass than the electrode lost. I know that ideally the anode oxidises zinc into zinc ions, and the cathode reduces zinc ions into zinc metal, suggesting that total mass should be conserved.

A key observation I made was that a white substance was observed on the anode, which probably led to the extra weight. Also, bubbles were observed on one of the electrodes. I am not sure which one though.

Edit: My chemistry teacher suggested this could be related to zinc oxide or zinc hydroxide, but I can’t find much information on this.


texts: How do we know that water has [H+] = 10^-7?

texts:
In the derivation of $K_\mathrm{w}$, the ionic product of water, it is stated that

$$[\ce{H+}][\ce{OH-}] = K_\mathrm{w}$$

and substituting $[\ce{H+}] = [\ce{OH-}] = 10^{-7}$ we can find that $K_\mathrm{w} = 10^{-14}$.

How do we know, though, that $[\ce{H+}] = 10^{-7}$? And why is $[\ce{H+}] = [\ce{OH-}]$?


texts: Writing water as a reactant in acid/base dissociation (Brønsted Lowry)?

texts:
The dissociation of $\ce{HCl}$ in water is written as:
$$\ce{HCl (aq) -> H+ (aq) + Cl- (aq)} \tag{1}$$
Sometimes we also include $\ce{H2O}$ as a reactant to stress the fact that the protons are not isolated in water.
$$\ce{HCl (aq) + H2O (l)-> H3O+ (aq) + Cl- (aq)} \tag{2}$$
The last equation is quite useful to establish what is the conjugate acid and what is the conjugate base in Brønsted-Lowry's theory, as far as I understand.
Let's do the same thing for a strong base, say $\ce{NaOH}$. We write the dissociation in water:
$$\ce{NaOH (aq) -> Na+ (aq) + OH- (aq)} \tag{3}$$
What if I wanted to write equation $(3)$ in a form analogous to equation $(2)$? I tried including water as a reactant in the same way but then it yields a chemical equation where $\ce{H2O}$ is on both sides, so we can elide it.
In Brønsted-Lowry theory we generally write $\ce{H2O}$ in the dissociation for acids and for some basis, say $\ce{NH3}$. Why don't we do it for Arrhenius bases like $\ce{NaOH}$ or other hydroxides?


texts:
I am considering building a stove out of stainless steel. I want to us stainless steel because the stove will have a double outer jacket to pass water through and heat it.

Will a wood fire sitting directly on stainless steel corrode it? Would a higher grade of stainless steel, say 316 instead of 304, prevent this?

Should the stainless steel be protected in some way, perhaps by a bed of fire bricks (at least) under the fire, to prolong its life? Or will stainless steel stand up to exposure to fire without corroding for a long time?


texts: What makes Kleenex Cool Touch tissues cool to the touch, and is it safe?

texts:
I love Kleenex Cool Touch tissues.  I'm just wondering what makes them actually feel cool.  For some reason it makes me think of refrigerant but I'm sure that's not in them.

Is it the combination of common ingredients that somehow gives it a moist feel, making it feel cooler than normal tissues?

Are the tissues safe to put to your face, if you are potentially inhaling the ingredient(s)?

Ingredients:  Stearyl heptanoate, stearyl alcohol, polyethylene, mineral oil, coconut oil, aloe


texts: Use of TsN3, toluene at high temperature

texts:
My reasoning:
My understanding is in first step the alcohol’s O- does an Sn2 attack on the OTs containing carbon. In the second step I am confused where does the reaction happen in the triple bond or at the O-C-O Carbon?


texts: Is there a non toxic moisture indicator that can be applied on a wall?

texts: I am looking for a substance that could serve as an indicator for a risk of mold growth, e.g. by a change of its hue. Cobalt chloride is both irritant and carcinogenic so is not an option. I've found this indicator but its threshold (8%) is not relevant for mold growth on a concrete and plaster wall which I guess is probably around 15-20% (I've found data only for wood where the threshold is 16%).


texts: What is a 'triplet biradical transition state'?

texts:
My text book just referred to this term. I have absolutely no idea what it is. Articles on the internet are too difficult for me to comprehend.

In some alkenes, steric crowding in the planar state may be so severe that the latter is no longer an energy minimum but becomes an energy barrier with the ground state becoming twisted. In this context the compounds in figure are of interest. The drop in rotational barrier from stilbene ($\pu{42.8 kcal mol-1}$, $\pu{179 kJ mol-1}$)to compound $\ce{P}$ ($\pu{21.1 kcal mol-1}$, $\pu{88.3 kJ mol-1}$) to compound $\ce{Q}$ (“small barrier”, cf.) may be explained by increasing stabilization of the triplet biradical transition state. However, the “negative” barrier in $\ce{R}$, that is, the fact that the stable ground state of $\ce{R}$ is non-planar and that the planar conformation represents the transition state for rotation requires a different explanation; the difference between $\ce{Q}$ and $\ce{R}$ is presumably due to the steric interaction of the four chlorine substituents in the planar conformation of $\ce{R}$. This situation resembles that in o,o'- tetrasubstituted biphenyls to alkenes with low or “negative” barriers.

This is the question given: for which the above is the solution

Source: "Advanced Problems in Organic Chemistry by MS. Chouhan 9th Edition", Chapter GOC, page 53


texts:
I watched a video showing an orange solution that goes to clear and then back to orange (and so forth.) The reaction goes through a number of cycles before it will no longer oscillate. This tells me that the overall energy in the system dissipates over time, but how does such a reaction work?

What is happening that causes this oscillation in concentration?


texts: Why there isn't any unimolecular addition reaction?

texts:
In my textbook, I have read about unimolecular elimination and nucleophilic unimolecular substitution reaction of organic compounds. In those reactions, firstly one bond breaks automatically then as soon as a carbocation forms then a nucleophile attacks the carbocation to complete the reaction.

Now, my question is: Why doesn't the same happen in case of addition reaction of molecules having double bond? One bond breaking may cause a charge separation and then nucleophile/electrophile can attack the positive or negative charged side? I know molecules with charge separation aren't supposed to be much stable. But even in the case of a carbocation the same happens.

I have Googled for unimolecular addition reaction but all the results were about unimolecular substitution/elimination.


texts: Do polarizability and electron delocalization have analogous effects on leaving groups?

texts:
With respect to bimolecular substitution and bimolecular elimination reactions, both electron delocalization and polarizability have an analogous effect on a species, making them good leaving groups.

For example I- is a good leaving group since its negative charge is spread out over a large area.

Also, the tosylate ion is a good leaving group because of electron delocalization where its electrons are spread out over a large area due to resonance stabilization.

However, the analogy seems to break down when considering their nucleophilicity in aprotic media, I-  is a good nucleophile and tosylate is not.

Is there a fundamental problem of the analogy between polarizability and electron delocalization?


texts: Relation between size of ion and hydration energy

texts:
Suppose I take 1 tablespoon of an ionic crystal and put it in excess water. We know that shall the hydration energy of the crystal be more than the lattice energy, the crystal will separate in ions and water molecules will surround each ion, making it soluble.
I wonder if the relation is direct or inverse in:
i) Anion's size and hydration energy
ii)Anion's size and lattice energy
iii) Cation's size and lattice energy
iv) Cation's size and hydration energy

I think the Cation's size is directly proportional to the hydration energy, since the bigger the atom, more easily shall it form the bond with the water molecules. The Anion's size should be inversely proportional to the hydration energy as the bigger the atom, more difficult would it be to form a strong bond between the water molecules. Similar reason goes for the other two.

PS: I'm new in chemistry so please try to explain a little.


texts:
I have heard and read about astatine's radioactivity, and it makes no sense to me. Why is it so unstable?  Uranium has a half life ranging from 70 to 4.5 billion years (natural isotopes), and it has 7 extra protons to deal with. I know that atomic nuclei can be stabler if they are spherical, implying that if you make a nucleus that isn't spherical you could destabilize it, but astatine has a maximum half life of 8 hours. Can someone explain this to me?

Information came from a few sources, including SciShow and Wikipedia.


texts: Relative Solubilities of Salts in Acidic Solution

texts:
I stumbled across this problem which I don't understand the answer to:
Which solid is much more soluble in 1 M $\ce{HCl}$ than in $\ce{H2O}$?
(A) $\ce{CaHPO_4}$
(B) $\ce{CaCl_2}$
(C) $\ce{BaBr2}$
(D) $\ce{BaSO4}$


texts: Is it possible to have Volume(solution) < Volume(solvent before adding solute)?

texts:
I understand the answer to the question "Is it possible to have Volume(solution) < Volume(solvent) + Volume(solute)?" is "yes" -- but it is possible that adding a solute causes the solvent to contract so much that the volume of the solution is less than the initial volume of the solvent?

An ideal answer would include either a specific example of such a case, or an explanation of why it is impossible.

If the above is not possible, is it possible for the volume of the solution to equal the initial volume of the solvent?


texts:
Here is a problem I just don't see how to get around... The following equation describes the oxidation by $\ce{O_2}$ of a phenolic compound, catalysed by an enzyme $\ce{E}$.

$\ce{4R–OH + O_2 ->[r] 4R–O. +H_2O}$

$r=k\frac{\ce{[R-OH]}}{\ce{K_M +[R-OH]}}[\ce{E}][\ce{O_2}]$

Rate $r$ is the speed at which $[\ce{R–OH}]$ is consumed. It tells us that our reaction follows a Michaelis-Menten kinetic law with respect to our substrate $[\ce{R–OH}]$ and first order kinetics with respect to oxygen.

First, we are asked to find a way by which the rate equation could be simplified by approximation.

We are told that initially,  $[\ce{R–OH}] = 10 mol/m^3$ and that we want a $95\%$ conversion of that reactant. We also know that $K_M =0.04 mol/m^3$. Therefore $[\ce{R–OH}]$  can vary between being $250$ times and $12.5$ times greater than $K_M$, so we could approximate the problem by getting rid of $K_M$ which would leave us with the following rate:
$r=k[\ce{E}][\ce{O_2}]$. Since $[\ce{E}]$ is constant, we could write $r=k'[\ce{O_2}]$. (This sort of trick has been used before in my chemical engineering class.)

The next question is the one I am struggling with.

We are asked to use our new kinetic rate law to write down the material balance equation expressing how $[\ce{R–OH}]$ would changes with time in a batch reactor (perfectly stirred, no input or output), then solve for $[\ce{R–OH}]$.

So I would be inclined to write $\frac{d[\ce{ROH}]}{dt}=-r=-k'[\ce{O_2}]$ but then I don't see how this can be solved since we have two different variables.

From the stoichiometry we can see $\frac{d[\ce{ROH}]}{dt}=4\frac{d[\ce{O_2}]}{dt}$ therefore $\frac{d[\ce{O_2}]}{dt} = -\frac{1}{4}k'[\ce{O_2}]$ and this can be integrated to give us $[\ce{O_2}]=[\ce{O_2}]_0e^{-k't/4}$. But how can the rate law be solved for $[\ce{R–OH}]$ ?

Any insight into this problem would be hugely appreciated.


texts: Calculating solubility in water with other species present

texts:
I'm very confused about calculating solubility.

Everything is in temperature of $298\ \mathrm K$

From Atkins's book, exercise 16.83:

Based on solubility constant, calculate solubility of $\ce{Al(OH)3}$ in acid solution of $\mathrm{pH}=4.5$, $K_{\rm s}=1\cdot10^{-33}$.

Using stoichiometry and equilibrium constants I proceed as follows:

$\mathrm{pH}=4.5$ corresponds to $\mathrm{pOH}=9.5$ and

$$\ce{Al(OH)3 (s) \rightarrow Al^3+ (aq) + 3OH- (aq)}$$

$$K_{\rm s}=\ce{[Al^3+][OH- ]^3}$$

Let's call $\ce{[Al^3+]} = x$.

From stoichiometry and the assumption that $\ce{[OH- ]} >> 10^{-7}$ we know that $\ce{[OH- ]} \approx 3x+10^{-9.5}$.

We get a equation like

$$x(3x+10^{-9.5})^3=K_{\rm s}$$

which I solve as $x=2.39\cdot10^{-9}$, but Atkins's answer is $3.0\cdot10^{-5}$.

Atkins's solution looks like:

$$K_{\rm s}=\ce{[Al^3+][OH- ]^3}$$

$${K_{\rm s}\over[\ce{OH-}]^3}=[\ce{Al^3+}] = 3.0\cdot10^{-5}$$

It looks like Atkins assumes that $[\ce{OH-}]=10^{-9.5}$.

I have two questions:

Why does Atkins assume that $\ce{Al(OH)3}$ doesn't affect $\mathrm{pH}$?
Which one is correct?


texts: Can benzene damage rubber or other materials or adhesives used in tire production?

texts:
In this article, "Bridgestone/Firestone, Inc. and Ford Motor Company: How a Product Safety Crisis Ended a Hundred-Year Relationship" the article states, "Industry observers have speculated [that]... a disproportionate amount of Benzene was added to the rubber compound which affected the adhesion in the years to follow," and "Excessive use of benzene can damage the quality of the tire material."

Is it true that too much Benzene can damage tires, either the rubber, the adhesives, or other materials used in tire manufacturing?


texts: What is the intuition and motivation behind the definition of the thermodynamic activity?

texts:
Stuck proving the relation $$\mu_i=\mu_i^\circ + RT\ln a_i,\tag{1}$$ I looked up the definiton of activity. It is

$$a_i=e^{\frac{\mu_i-\mu_i^\circ}{RT}},\tag{2}$$

but the the intuition/motivation for such a definition is unclear. Is it just because we wish for a relation like $(1)$ to exist by analogy with $(3)$? $$G_i=G_i^\circ+n_iRT\ln{\frac{p_i}{p^\circ}}\tag{3}$$

That is, if we define activity as given in $(2)$, we can take the natural logarithm of both sides, multiply with $RT$, add $\mu_i^\circ$ to both sides and arrive at $(1)$. And hence $(1)$ has a similar form to $(3)$ which holds for ideal gases.

Or am I mistaken and there are other reasons at play?

$\mu_i$ is chemical potential
The superscript $^\circ$ denotes the standard state
$a_i$ is activity
The subscript $_i$ denotes the $i$-th component of a mixture


texts: Does the amount of solute affect rate of solvation?

texts:
I know that in order to increase the rate of solvation, you need to increase how often solute and solvent particles come into contact.

You can do it by:

agitating the mixture
increasing the surface area of the solute
heating up the solvent

But my question is: Does adding more solute (like adding more salt to water) increase the rate of solvation since the contact surface area is larger?

Edit: The original question in the book describes dissolving a certain amount of $\ce{NaCl}$ into water and asks, “What can be done to increase the rate of dissolution without affecting solubility?” I assume the rate is measured by how fast the mass of $\ce{NaCl}$ is consumed, which is $-\frac{dW}{dt}$.


texts: How exactly do alcohol molecules dissolve in seawater?

texts:
The book "Lehrbuch der anorganischen Chemie" by Arnold F. Hollemann on page 47[link here][1] states that dropping 0.8g Alcohol (M = 46g/mol) in a sea or ocean would result in every litre seawater containing 8 molecules alcohol.

This completely baffles me. How exactly does this happen?

[1]: https://books.google.de/bookshttps://books.google.de/books?id=eGkvSDAqY9gC&pg=PA47&lpg=PA47&ots=MFR61amS0x&focus=viewport&dq=ein mol alkohol in den weltmeeren&hl=de&output=html_text


texts:
Dextrin is labelled as highly soluble in water. I have white dextrin (analytical from Sigma Aldrich). When I mix it in water, no matter how long I stir and how little dextrin I put, I get a suspension. The dextrin does not dissolve.

I am not a "real" chemist. If I search on Google with keyword such as dextrin water solution, nothing pops up, except that dextrin is highly soluble in water.

I must miss something obvious. I just don't know what. If someone could point me in the right direction...


texts:
For the same principal quantum number, on increasing the value of the azimuthal quantum number does the average radius of the subshell increase or decrease?
In other words, which out of, say, 3s, 3p, 3d would have the largest average radius and why?


texts:
I was trying to remove the electroplating from a aluminum rod using inverse electrolysis and everything went wrong. I'm definitely not a chemistry expert, so I'd like to know what happened here.

I used hydrochloric acid (30%) as the electrolyte, the aluminum rod as the cathode and a common copper wire as the anode. I ran it through a 12V 1A power supply, in a small glass jar.

When I turned the power on a lot of bubbles started to appear at the surface of the rod, as expected. After aproximately 30 seconds the bubbling was too strong, so I decided to turn off the power supply, however, the bubbling didn't stop. As I know that electrolysis of hydrochloric acid releases chlorine, I decided to put the jar to outside, with both electrodes still inside it. After aproximately five minutes, to my surprise, the jar was bubbling extremely strong, spilling over and the electrolyte had turned black, and quite frankly it was kind of scary.

I removed the electrodes and the reaction ceased, but I still have no clue of what happened.


texts:
I never thought that modern American nickels actually contained nickel anymore. However, according to this wiki article, the coins actually do contain 25% nickel, the rest being copper. And yet, no US coin produced today is officially magnetic. Why is this alloy of nickel not attracted to a magnet?

(and yes, I tried time and again to find and answer elsewhere online.)


texts: Liquifying metal and toxic fume exposure

texts:
I just read a very entertaining Youtube comment thread on a video where TheBackyardScientist melts tin on the stove in his (enclosed) kitchen, the proceeds to cook a steak on it.

According to the mass of commentaries (and votes), what he did was idiotic due to the toxicity of the fumes released when melting the tin, and the fact that he was in an enclosed space without a respirator.

Reading about tin and organotin compounds a bit, nothing is mentioned about them being 'released' upon melting, but rather that they are a particular subset of compounds of tin, and some happen to be toxic.

Regarding 'metal fume fever' and its causes, it seems that it is a small subset of metals that when oxidized could cause nervous system damage, in which tin does not take part.

Aside from burning yourself horrendously, what dangers are associated with the melting of (we can assume nearly pure) tin, particularly in a closed space? Is what he did really that dangerous?


texts: Compounds that vary water's superheated and supercritical limits

texts: Are there any compounds that reduce water's sensitivity to extreme heat change and/or volatility to high heat (over 800 degrees Fahrenheit), whether organic or inorganic?


texts:
First of all, is the problem even worded correctly? From how the problem is worded, it seems that copper is being oxidized as well as iodide ion. This is what I am taught:

Second of all, I'm not getting 0.24 volts as the cell potential. I'm getting 0.19 volts.

Here is my work. What am I doing wrong?


texts: What's the minimum amount of energy needed to remove CO2 from the atmosphere?

texts:
I've been learning about CDR (Carbon Dioxide Removal) techniques to combat climate change. These all seem to involve extracting $\ce{CO2}$ from the atmosphere and converting to a mineral, which is then buried.
I am not a chemist, but something seems wrong about this to me.  Wouldn't the decrease in entropy need to balanced by an increase of entropy somewhere else, e.g., by using up a low entropy source of energy?
Is it possible to come up with a theoretical lower bound for the amount of energy needed to extract $\ce{CO2}$ as a proportion of the energy obtained by burning the fuel that released it in the first place?
If this is more than 100% then CDR schemes cannot possibly be an alternative to decarbonising our energy sector asap.  Even if it's less than 100% the calculation is still useful as it allows us to compare the true cost of fossil fuels with renewables, e.g., a value of 33% would indicate that the cost of fossil fuels is 50% higher than advertised (assuming we remove the $\ce{CO2}$, otherwise it's infinitely more expensive!)
(Edit)
Assume the original CO2 came from coal at 24MJ/Kg.
I’m not going to specify the mineral to which this is converted because I’m looking for a theoretical lower bound across all (scalable) technologies.


texts:
Back to chemistry after 2 months and got stuck in the beginning! That's why I don't like it. Anyways, come to the question please.
Following are the words from my textbook (Don't ask the name ;-)

$$\ce {Na -> Na^+ + e^-}\quad\Delta{H}=+495 \frac{KJ}{mol}$$
$$\ce {Cl + e^- -> Cl^-}\quad\Delta{H}=-348 \frac{KJ}{mol}$$
$$\ce {Na^+ + Cl^- -> NaCl}\quad\Delta{H}=-786 \frac{KJ}{mol}$$
We conclude that it is essential for the formation of ions and ionic bond  that the sum of energies released in second and third reactions must be larger than what is required in the first step.
The great attractive forces (bonds) reduce the energy of the system greatly as it emits 786 KJ of energy.

a. Why should it happen? i.e. sum must be greater et cetera.
b. How does attractive forces tend to reduce the energy?


texts: Are there any early industrial age methods capable of determining diamond or graphite's crystalline structure?

texts: I'm writing a fictional story with early industrial age technology where a chemist discovers not only that diamond and graphite are made of the same substance, but that they differ by crystalline structure (cubic vs hexagonal).  However, I'd like this to be a realistic depiction if possible and the chemist does not have access to electron tunneling microscopy or advanced spectrographic methods.  The farthest spectroscopy has gotten is Fraunhofer's spectroscope and John Herschel's evaporogram, with visible light and the beginnings of an understanding of infrared and ultraviolet.  Would 1850's level spectroscopy or other technology of the time be able to demonstrate the crystal structures of carbon (specifically graphite and diamond) without a 1900's understanding of atomic structure?


texts: How can you change the proportions of reactants and products at equilibrium if Le Chatelier's principle is occurring?

texts: For example, how could you make a buffer with equal concentrations of acid and conjugate base? If you add more conjugate base, it will shift the equilibrium to form more acid, which will keep the proportions of each the same. So how can you achieve equal concentrations if this is happening?


texts: Filtering fine particles before work-up (Tosylation)

texts:
I am trying on doing tosylation of PEG using Tosyl Chloride with pyridine. Some articles mentioned about filtering fine particles (pyridinium salts?) after diluting with DCM. But they did it with some filter-aid like celite which I don't have access to.

On my first try, I didn't filter it and during washing (HCl, NaHCO3, brine), there seemed to be a pretty intense emulsion. I am wondering if it was caused by those particles I didn't filter.

I also tried to quench it with water instead of dcm then extract with DCM, the emulsion thing still occured.

Therefore, I would like to ask if there is any other methods of filtering those fine particles beside filter-aid. Would syringe filter work?

Thanks a lot


texts: Do acetals and hemiacetals give 2,4 DNP test?

texts:
Do acetals and hemiacetals give positive 2,4 DNP test?
The reagent for the reaction is described as:

An aqueous solution of 2,4-dinitrophenyl hydrazine (DNP) is known as Brady's reagent

I recently learnt that acetal don't give positive tollens test whereas hemiacetals did.
Following from the same conclusion I believe that since its an aqueous solution and seems alkaline aswell so according to me acetals should give negative 2,4 DNP Test whereas hemiacetals should give positive.
However I fail to find any literature on this, are my conclusions correct or are there any twists to it!?


texts: Which easy-to-acquire clear liquid would be best for testing whether or not a twenty-sided die is balanced?

texts:
In another question on another stack, I asked if the Saltwater float present in a specific youtube video was capable of determining any differences in mass between the faces of a die in determining the balance of a group of dice, and was met with very good results and a positive affirmation that yes, it was very possible to do so.

Which led me to believe that there was a possibility that denser liquids might have the possibility of testing the balance of the dice even better, with much less mess. This led me to go through and search the densities of many liquids to determine which would be best for the job.

Water came in at ~1g/mL at room temperature, which was the medium for the test initially.
Saltwater was at about ~1.028g/mL. Dice were able to float in this.
H2O2 (Hydrogen peroxide) clocks in at ~1.44g/ML, but I tested this one myself with a commercially available H2O2 and was unable to float dice in it just on its own. It isn't dense enough to float a die on its own.
Originally I thought Galium might be a good choice since it has a high density and is very easy to melt, but it isn't transparent.

So the question is this:

Is there a liquid, that is easy to acquire, that has a higher density than H2O + MgSO4 (Epsom Salt), that it would be easier to test a dies balance in and at what density does a d20 float?

Generally when referring to dice, the most well known manufacturer is probably Chessex. The dice are made out of some kind of plastic polymer of some sort. I don't really know any specifics about their chemical composition, but they could just be injection molded plastic dice.

As for the approximate mass of said dice.. This site states that the dice themselves are ~5mg (That doesn't sound right. I learned in school that a Paper clip is a gram, Dice weigh much more than a paper clip..)


texts: Why draw "up" arrows first when filling orbital diagrams?

texts: I am a 11th/12th grade student studying orbital configurations. I have gone over this lesson and it says to always draw spin up first. However, it never says why. Is drawing down spins first incorrect?


texts: Can we classify all the d-block elements as transition metals?

texts:
I thought that properties of d-block elements are transitional between those of s-block and p-block elements, and that is the reason for calling them transition metal.

My textbook says that not all d block elements are called transition metals.

My doubts:

What are these non-transition metals that are in d-block?
Why are these specific elements not called transition metals?


texts: Generating hypochlorous acid for disinfecting water using HClO2

texts:
I use a product that contains $\pu{700 ppm}$ of $\ce{HClO}$ to disinfect water at $\pu{1 ml}$ per $\pu{1 l}$ and let it rest for about $\pu{2 hrs}$ before I use it so there is no $\ce{HClO}$ left because I will mix it with enzymes and rhizobacteria which could be destroyed by the $\ce{HClO}$.
I found a device (Eco One Electrolyzed Water System) that can generate $\ce{HClO}$ at $\pu{200 ppm}$ using just water and $\ce{NaCl}$ at a $\mathrm{pH}$ of $5$, which would be much cheaper in the long run.
Will this have the same disinfectant effect when I add $\pu{3.5ml}$ per $\pu{1 l}$ water of the $\pu{200 ppm}$ solution and should I also let it rest for $\pu{2 hrs}$?

In a closed container such as a spray bottle, the concentration of hypochlorous acid decreases about $1\%$ per day.

Are there any buffers or stabilizers that I can add to the generated $\ce{HClO}$ to slow down this process which are safe and environmentally friendly when the water is used for watering fruit plants?


texts: Gauche correction in Bensen group increment

texts: I have difficulty understanding the use of gauche correction in Bensen group increment method to calculate the heat of formation. As an example, 4 times gauche correction (0.8 kcal / mol) is considered in the calculation in the hypothetical equilibrium between the following two isomers. How is that figure decided?


texts: Which allotropes of sulfur exist naturally?

texts:
I'm writing a paper on chemistry and I would like to know which allotropes of sulfur exist naturally. I've searched on the Internet but I haven't found anything about natural sulfur allotropes except this book(Ref. 1). Does anyone know the answer?
Reference

Steudel R., Eckert B. () Solid Sulfur Allotropes. In: Steudel R. (eds) Elemental Sulfur and Sulfur-Rich Compounds I. Topics in Current Chemistry, vol 230. Springer, Berlin, Heidelberg, DOI: doi.org/10.1007/b12110


texts: Why does SN1 not occur as a minor product when a strong nucleophile/strong base attacks a tertiary substrate?

texts:
The following is part of a table that appears in my Organic Chem Text (Klein)

Nucleophile Only (e.g. Strong Nucleophile/ Weak base)

$1^\circ - \text{ SN2}\\
2^\circ - \text{ SN1 + SN2}\\ 3^\circ - \text{ SN1}\\ $

Strong Nucleophile/ Strong base

$1^\circ - \text{ SN2 (maj) + E2 (min)}\\
2^\circ - \text{ SN2(min) + E2 (maj)}\\ 3^\circ - \text{E2}\\ $

Why will SN1 not also occur on tertiary substrates if the attacking nucleophile is also a strong base? That is, why doesn't it read $$3^\circ - \text{E2(maj) + SN1(min)}$$


texts: What are the byproducts in a Suzuki reaction?

texts:
I am looking precisely at a coupling of a trifluoroborate with an aryl bromide. I know the mechanism of the Suzuki reaction, yet I cannot find any mention of the side products or degradation products that one could obtain if the coupling fails. Maybe those products are obvious for those who know well how palladium reacts, but this is not my case. I tried to find a book that would give me a feel for what might happen and could find anything close enough.

I'm expecting a protodeboration as a side reaction, yet I can't find any source nor mechanism. Could anyone shed some light on the subject?


texts: Does mass equal to moles times molar mass take into account coefficients?

texts:
I have an equation $$\ce{ 2NaN3 -> 2Na + 3N2}$$ I've calculated there are $\pu{4.4 moles}$ of $\ce{N2}$ (using the data given in the question). I then did $\large{\frac{4.4}{3 \cdot 2}}$ to get number of moles required of $\ce{NaN3}$ (although if this is wrong then correct me). And now I want to calculate the mass of $\ce{NaN3}$ used (knowing there are $\pu{3 moles}$).

Where I have $\pu{ 3 moles}$ of $\ce{2NaN3}$ and I want to calculate mass do I use the $\mathrm{M_r }$of $\ce{M_r(NaN3)\cdot 2}$ or just a single mole of it.

Eg:
 $\text{mass = moles} \cdot  \mathrm{M_r} = 3 \cdot 65 $ or $\text{mass = }~3 \cdot 130$?


texts:
I was working on an assignment I had a question about conformations of a molecule about a single bond.
Given a random molecule like this with multiple large substituents on one side of the $\ce{C-C}$ bond (in this case, $\ce{CH3}$ & $\ce{C2H5}$), is the molecule considered to be anti when the largest substituents on either side of the $\ce{C-C}$ bond are opposite of each other? (i.e. would the $\ce{CH3}$ need to be an $\ce{H}$ atom to be considered in the anti conformation)?


texts:
Recently, I learnt that by adding a non-volatile solute to a solvent, the  vapour pressure of the solution is decreased and consequently its boiling point.

Facts and definitions

freezing point: "The temperature at which the vapour pressure of the substance in its liquid phase is equal to its vapour pressure in the solid phase."

So as the solution cools down, the vapour pressure decreases and eventually equals the vapour pressure of the solid.

My argument as to why depression in freezing point shouldn’t take place

consider this argument:the atmospheric pressure is constant regardless of the temperature of the solution.

As we cool down a solution, we are basically removing the kinetic energy of the solution's particles  so due to less kinetic energy and due to atmospheric pressure the Van der Waal's forces come to play, hence turning the solution into a solid state.

the pressure exerted on the liquid by the atmosphere is the same whether you add a solute or not, so no depression of freezing point should take place.

Reality check

I know that this argument is not true, as experiments proves the colligative properties are true.

Where and why my "intuitive" argument is failing?


texts: Why are the Covalent Radii of Ruthenium and Osmium So Similar?

texts:
Osmium and Ruthenium have covalent radii 144 and 146 respectively (according to Wikipedia).

How are these values so similar when Osmium has 32 more electrons, with another filled p, s, and f orbital beyond Ruthenium?

Is it just because they have similar outer electron configurations?


texts: How Fittig reaction gives good yield if phenyl cations are unstable?

texts:
I am confused,after reading from NCERT text that phenyl cations are unstable due several reasons like the carbon in phenyl group is sp2 hybridized,resonance structures do not stabilizes the phenyl cation.But then,in Fittig reaction we do have phenyl cations as intermediate.For example in a reaction between two molecules of chloro benzene and sodium metal we get a diphenyl molecule.Here we have two phenyl cation generated (if i am right).Then what factor stabilizes the phenyl cation?If there is any error in the theoretical aspect of the question please help me correct it as i am not quite sure about the mechanism.

I would be very much glad to accept an answer with some thermodynamical data like the bond enthalpies of C-Cl bond and newly formed product's bond enthalpy that is C-C bond enthalpy(in the case of diphenyl)and the total realease in energy.


texts:
I recently came across the statement

  The structure of crystalline $\ce{B2O3}$ consists of $\ce{BO4}$ tetrahedra, two sets of which form two types of interconnected spiral chains, three $\ce{B-O}$ bonds are equivalent, but the fourth one is somewhat longer.

Please explain the meaning of this statement, above is the image of crystalline $\ce{B2O3}$ from Wikipedia.


texts: What would oxygen or nitrogen snow look like?

texts: I was watching a video of what would happen if the earth got kicked out of the solar system and at one point it was mentioned that oxygen and nitrogen snow would form. So would such snow be any different physically to good ol' water snow? Would it be more fine or less dense? I'm asking this because I'm thinking of writing a story or something that uses that. Curiously, there seem to be almost no related results on the internet.


texts: How can they "wash away" the caffeine from Nescafe Gold to produce that "de-caf" version?

texts:
I buy and drink Nescafe Gold all the time. I also buy the smaller "caffeine-free" version of the same product. It tastes very differently, which makes me assume that the caffeine does have a lot of taste.

However, maybe it's not simply due to the lack of caffeine? Maybe the process with which they "de-caf" the original product (something about "washing it away", if I recall correctly from what I read/heard somewhere at some point) also removes other ingredients?

How can they possibly "wash away" just the caffeine from instant coffee like that?

Unless the truth is that the entire products are "built" from the ground up, separately for the caffeine-including and caffeine-less products, and the latter is not "based on" the former at all?

Even if so, they still have to "wash away" the caffeine from the raw coffee, which puts us back on square one...


texts:
I've been trying to find the values of any sort of percentage composition of diet coke and I haven't found any luck other than one interviewee (Dr. MAUREEN STOREY [Senior Vice President, Science Policy, American Beverage Association]) who states

Soda is comprised mostly of water. A full-calorie soft drink has 90 percent water, and a diet soft drink is 99 percent water. Water is the most important nutrient that we have...

And that was all the information I have.


texts:
For which pair of species is the difference in radii the
  greatest?

  (A) $\ce{Li}$ and $\ce{F}$

  (B) $\ce{Li+}$ and $\ce{F^-}$

  (C) $\ce{Li+}$ and $\ce{O^2-}$

  (D) $\ce{O^2-}$ and $\ce{F^-}$

I am pretty sure it is not (D) as $\ce{O}$ and $\ce{F}$ are quite close to each other on the periodic table and should have atomic radii pretty much the same.

I also know that gaining an electron increases the atomic radius whereas losing one decreases atomic radius. Also, as you move to the right of the periodic table atomic radius decreases.

I think that the answer could be (A) because $\ce{Li}$ is larger than $\ce{F}$, and the other choices result in $\ce{Li}$ becoming smaller and $\ce{F}$ becoming larger which decreases the difference in radii, but this is not the correct answer.

The answer given was C. How can this be explained?


texts: How to rationalise the resonance structures and hybridisation of the nitrogen in a conjugated amine?

texts:
I was given the first structure, and then drew the other 5 resonance structures:

First of all, are they correct? ChemBioDraw had some complaints, but as far as I can see there's the same number of electrons, and no valence orbitals exceeding capacity.

My reasoning is that the first structure contributes more. There's no electron deficiency on any of them, so we can disregard that. There is charge separation on the last 5 though, and in combination with this, the negative charge is on the least electronegative atoms, thus making the last 5 structures noticably higher in energy, and thus they contribute less to the true electronic image of the molecule.

Hope I'm correct so far; here's my question:

In the first structure, nitrogen is sp³ hybridised, but on all others it's clearly sp² hybridised. So what does that mean? It's somewhere in between, but closer to sp³-hybridised?


texts: If the heat exchanged is different for reversible and irreversible processes, how can enthalpy be a state function?

texts:
From the definition of Gibbs free energy, we can write for an irreversible process:

$dG=dH-TdS<0$

With $TdS=\pu{q_{rev}//T}$ this becomes:

$dH-dq_{rev}<0$

Since G is defined for constant (p,T) $dH=dq$, in the case of an irreversible process we can write $dq=dq_{irrev}$, so:

$dq_{irrev}-dq_{rev}<0$

Or, by default:

$dq_{rev}>dq_{irrev}$

BUT: since $dH=dq$, this would mean:

$dH_{rev}>dH_{irrev}$

Which is in contradiction with the fact that H is a state function (the path between 2 states shouldn't matter)! What am I missing here?


texts: In one of my classes, my teacher told me that benzene can be formed by cyclic polymerization of ethyne. But I think that benzene isn't a polymer because only 3 ethyne molecules are combining to form benzene whereas, thousands of monomers are combined to form a polymer in a polymerization reaction. So, after all, can benzene be called a polymer of ethyne?


texts: What is the noble gas configuration of copper?

texts:
Copper has an electron configuration of $\ce{[Ar] 3d^10 4s^1}$. Now sometimes the noble state is written as $\ce{[Ar] 3d^10 4s^1}$ or as $\ce{[Ar] 4s^2 3d^9}$.

Now the first noble state seems to be the same as his normal configuration and the latter seems to have equal electrons but divided in another way.

Now copper has two oxidation numbers $+1$ and $+2$ and as copper is d-element of the $4$ period it follows the $18$-electrons rule. But probably the $18$ electrons aren't created to get the krypton noble state. So how does the noble state configuration of copper work?


texts: Difficulty understanding redox in terms of hydrogen and oxygen transfer?

texts:
I have come across 4 ways of defining oxidation:

loss of electrons
increase in oxidation number
gain of oxygen
loss of hydrogen

From these definitions, I have an idea of what I think 'oxidation' and 'reduction' really refer to, but I would appreciate if someone could verify or tell me if I am going wrong.

I think oxidation and reduction simply refer to the degree to which the electrons of an atom 'dissociate' or 'distance' themselves from the nucleus of an atom. We define this extent of distancing to be 0 when an atom is bonded to another atom of the same element.

Thus oxidation really is 'loss of electrons', and reduction is 'gain of electrons', but the electrons do not have to be completely gained or lost. It is more like, oxidation is the valence electron shell moving further from the nucleus and reduction is the valence electron shell coming in closer to the nucleus. I.e. in a chemical reaction when the atoms surrounding a particular atom, say A1, are changed, the terms 'oxidation' and 'reduction' give a measure as to whether the atoms surrounding A1 have an overall effect of being more electronegative than the atoms that were bonded to A1 previously (in which case A1 has been oxidised) or less electronegative (A1 has been reduced).

Then the increase in oxidation number coincides with these definitions.

When it comes to REDOX in terms of hydrogen and oxygen transfer, I think this is only valid for organic chemistry. In general, loss of gain of hydrogen is to a carbon atom or an oxygen atom, or maybe nitrogen and sulfur too. As these are more electronegative than hydrogen, a gain in hydrogen means that these atoms can attract more electrons towards themselves, whereas a loss of hydrogen means that they lose electrons that they could be attracting towards themselves.

In terms of oxygen, in most of these organic systems it is gain of oxygen to carbon, sometimes nitrogen, which are less electronegative than oxygen. So by the same idea as above with hydrogen, a gain in oxygen corresponds to decrease of electron density being held around the atom, i.e. oxidation.


texts: Conversion of an alcohol to a methyl group

texts:
I'm only interested in the first conversion: D to E.

I've been thinking about this for a little bit. My first thought was to use $\ce{TsCl}$ to make a good leaving group then a $\ce{Me}$ nucleophile. This didn't seem like it would work since $\ce{Li-Me/MeMgBr}$ would just displace the leaving group. My second thought was to convert the alcohol to a halide, make it a Grignard reagent, then react it with $\ce{MeBr}$. But that also wouldn't work. Any suggestions?


texts: Why is absorbance the negative logarithm of transmittance?

texts: What is the physical significance of absorbance? Is it not possible to directly decipher the amount of radiant energy absorbed by the sample from transmittance? Why is that negative log of Transmittance is called absorbance?


texts: I wanted to figure out how many grams were to a lb and instead of looking it up I used my textbook and found 1 kg = 1000 g and 1 kg = 2.205 lb. I set up a cross multiplication equation to solve for x. The number I got was close but off by a few hundredths. I got 453.5147 g = 1 lb. I looked to see if I was right and found that the actual number is 453.59 g to lb. What did I do wrong?


texts: How to compare acidity in the following aniline derivatives?

texts:
Let the simplest one be a), ortho be b), meta be c) and para be d).
I have confusion between ortho and meta. How to compare their acidity?


texts: Potassium permanganate to analyze iron compounds

texts: In my lab, I used potassium permanganate in order to analyze the amount of iron in a compound with iron in the +2 oxidation state using titration. My question is how would this analysis be different if we were analyzing iron in a different oxidation state like +3?


texts: What is the chemical basis for superglues?

texts:
There are a variety of different types of glues, some derived from animal or natural materials and some designed by chemists. Some glues need to be activated before they harden and stick (many epoxies, for example) but others seem to stick very quickly without any obvious activation (like Loctite Superglue or The Original Super Glue).

What chemical reactions make these glues work?


texts: Is it possible to have same mass and volume for a solvent and its solution

texts: Is there any solute-solvent interaction possible, in such a way that a solvent with mass X grams and volume Y litres, and a solute with mass A grams and volume B litres, to form a solution that has exactly the same mass and volume as that of the solvent (X grams and Y litres)?


texts: How does oxygen fight odors? (Deodorant ad)

texts:
I saw an ad on tv last night for Mitchum deodorant that showed big text on the screen that said "OXYGEN eliminates all odors!" or something similar. Their website indeed claims "Our exclusive formula releases pure oxygen, a powerful odor fighter...".

How does oxygen fight odors, and how can this aspect of the deodorant be more effective than the abundance of pure O$_2$ in the air?


texts: Potassium carbonate vs. Potassium hydroxide in Wood Ash

texts:
I'm trying to get more concrete information about the chemical process of creating soap from wood ash.

What I’m confused about: Many soap-making materials say that you create potassium hydroxide directly from filtering water through wood ash. As far as I can tell this is false? You are actually getting potassium carbonate (and some small amount of other residue.)

To create potassium hydroxide from this, historically you would add a solution of calcium hydroxide (calcium oxide/burnt limestone dissolved in water). Calcium carbonate would precipitate out of the solution, leaving behind potassium hydroxide. From my understanding, a lot of modern soap-makers are simply misunderstanding the chemistry, or not realizing that the lime has to be added before they actually have potassium hydroxide.

However, some sources say that if the wood is heated hotter and given a more complete burn, thus combusting more of the organic material, then more hydroxides will be dissolved instead of carbonates, thus negating the need for lime. Is this true?

I have also read that if you take the potassium carbonate, dehydrated, and heat it to an (uncertain) degree, it will burn off carbon dioxide and create potassium oxide, which added to water will become potassium hydroxide. Is this true? How hot do you need to burn it, if so?

However, other sources say heating potassium carbonate only purifies it, creating pearl ash, which is still potassium carbonate.

Basically, I just need more information about potassium carbonate vs. potassium hydroxide from wood ash sources.


texts: Why does microwaving napalm make it nonflammable?

texts:
In this video, microwaving napalm made it nonflammable. What caused this to happen?

I assume it was some sort of chemical reaction. Could someone explain? I understand some chemistry, but a not-too-technical answer would be appreciated.


texts: Are esters soluble in Dichloromethane? I have a ketone with methyl group at one end and on the other end a big biphenyl group with a 6 carbon long aliphatic chain at 4'. I am planning to oxidise the keto group to acid using Baeyer Villiger oxidation but I am worried about the side product ester which may cause problem while separating my product.


texts: How to find the combining valence of an anion when it exhibits variable valency?

texts:
I'm doing an online course and can't for the life of me figure out how to write chemical formulas from the chemical name.

Take the example of calcium chloride.

I know the the valence for calcium is +2 because my periodic table shows me this, but I cannot figure out the valence of chlorine, (or any other element) with multiple valences. My periodic table lists chlorine as having a possible valence of -1, +1, +3, +5, or +7. How am I to know which one is to be used?


texts: I am studying nmr and the concept of multiplicity is very hard to undersand. Specifically I wanted to know where this arises form. Can anyone explain the concept of spin spin coupling in detailed and in simple terms?


texts: What are the priorities for substituent groups on a cyclohexane?

texts:
I was wondering about this specific scenario:
If you have a cyclohexane, for example, and the cyclohexane has two consecutive substituent groups, for example a methyl group and an ethyl group, how do you decide where the numbering starts?
Would it be 1-ethyl-2-methylcyclohexane or would it be 2-ethyl-1-methylcyclohexane?
Whoever answers this, could you just give some sort of general rules on what to do in this situation (e.g. does it follow alphabetical order, etc.)?


texts: How is it possible to dissolve zinc oxide safely for skin use, preferably without acid?

texts:
Zinc oxide comes as a powder that is insoluble in water but soluble in most acids.

I once received a clear liquid containing zinc oxide from an Italian pharmacy as a deodorant.

What could they have used to make the $\ce{ZnO}$ soluble and safe for use on the skin?


texts:
I was reading the book: " Nanotechnology: A Gentle Introduction to the Next Big Idea" and I came across this sentence:

  For these molecules to perform useful functions, they must be easy to
  assemble and easy to recognize and bind to by other molecules.

Who can explain this sentence? I have problem with "easy to assemble and easy to recognize" part?

It was in the paragraph below:-

  Generally, the molecules found in nature are complex and the source of
  much dismay to beginning organic chemistry students. For these
  molecules to perform useful functions, they must be easy to assemble
  and easy to recognize and bind to by other molecules. They must also
  be made by biological processes and have variable properties.


texts:
In which of these cases would the addition of $\ce{Br2/H2O}$ be highly regioselective?

$$\ce{CH3CH=CHCH2CH3}$$ or $$\ce{(CH3)2C=CH2}$$

since both are asymmetric alkenes, how do I answer the question?


texts: Can decarboxylation of carboxylic acids be effected by bases other than soda lime?

texts:
What about other bases such as Group 1 or Group 2 hydroxides? Does it have to do something with the mechanism?

I don't understand the mechanism either:

What is NaOH supposed to with the acetate ion? I thought the acetate ion would be produced when NaOH reacted with acetic acid after which the reaction would proceed as follows:


texts:
In the context of the wave functions of electron in a hydrogen atom, I just want to get clear regarding the terms probability and probability density of an finding an electron. To be precise, we know that the value of $|\Psi|^2$ at a point gives the probability density of the electron at the point. Now, does that imply that if the value of $|\Psi|^2$ is maximum at a point, the electron is most likely to be found at that point?

Reason for my doubt: The question given by my instructor goes:

  Given that the normalized wave fuction of the electron in $\mathrm{3d}_{z^2}$ orbital of an Hydrogen atom is:
  $$
\Psi = N \sigma^2 \mathrm{e}^{-\frac{\sigma}{3}}(3\cos^2\theta-1) \, ,
$$
  where $\sigma={\frac{r}{a_o}}$

  Now where is the electron most likely to be found?

The solution given goes like:
If $P$ represents probability of finding the electron and $\mathrm{d}V$ the volume element then,
$$
\frac{\mathrm{d}P}{\mathrm{d}V} = |\Psi|^2
\implies
\mathrm{d}P=|\Psi|^2 \mathrm{d}V$$
Also since,
$$\mathrm{d}V = r^2 \sin\theta \mathrm{d}r \mathrm{d}\theta \mathrm{d}\phi$$
We get,
\begin{align}
\mathrm{d}P &= |\Psi|^2 r^2 \sin\theta \mathrm{d}r \mathrm{d}\theta \mathrm{d}\phi \\
&= N_1 \sigma^4 \mathrm{e}^{-\frac{2\sigma}{3}}{(3\cos^2\theta-1)^2} \sigma^2 \sin\theta \mathrm{d}\sigma \mathrm{d}\theta \mathrm{d}\phi \\
& = N_1 [ \sigma^6 \mathrm{e}^{-\frac{2\sigma}{3}} \mathrm{d}\sigma ][ {(3\cos^2\theta-1)^2} \sin\theta \mathrm{d}\theta ][ \mathrm{d}\phi]
\end{align}

He later maximized the $[\sigma^6 \mathrm{e}^{-\frac{2\sigma}{3}}]$ and $[{(3\cos^2\theta-1)^2} \sin{\theta}]$ terms to get the values of ${\sigma}$ i.e. hence $r$ and ${\theta}$ at which the electron is most likely to be found. Infact, he stressed on the maximization of ${\theta}$ part which came out to be $0$. And hence, a conclusion made that for an electron in $\mathrm{3d}_{z^2}$ orbital, the electron is most likely to be found in the XY plane.

I find all this stuff confused and fishy. Can someone explain me this solution or prove it wrong via a right way of solving this question.


texts: How to determine the efficiency of intermolecular charge transfer?

texts:
Lets say we have 2 molecules: A and B. Both of these molecules associate with another molecule C. Upon association two complexes form A-C and B-C. We can experimentally see that upon association a new charge transfer (CT) absorption band appears, additionally intensive CT emission appears. Additional evidence for CT can be obtained by DFT calculations (where HOMO is located on A or B and LUMO is located on C). By determining photo luminescence quantum yields (PLQY) it can be seen that A-C has 4 times higher PLQY than B-C.
Are there any ways to determine whether specifically the efficiency of the CT is responsible for this drop of PLQY?


texts: Why does indolizine undergo EAS on C3 and not C5 of the pyrrole ring?

texts:
In Clayden, Greeves, & Warren: Organic Chemistry Second Edition, it is said that indolizine (pyrrocoline) reacts in electrophilic aromatic substitution at the C3 of the pyrrole ring, as shown.

I understand that it reacts at the pyrrole ring because the pyrrole ring is more nucleophilic than the pyridine-like ring, but I don't understand why it doesn't react at the C5 position of the pyrrole ring (like pyrrole does); the sigma complex at the C5 position has more extensive delocalization, whereas the sigma complex at C3 is less stable cross-conjugation.


texts: Covalent atomic radii: oxygen vs nitrogen

texts:
Many books state that $R_\ce{N} > R_\ce{O}$ which is in accordance with the general trend. However, some books say that $R_\ce{O} > R_\ce{N}$ because of repulsion caused by pairing of electrons.
Which one is correct and should be followed?
Older version of NCERT, cengage, arihant and JD Lee state the latter, while the newer version of NCERT, Wikipedia and many websites say the former. Why was the theory discarded?
Note: van der Waal's radii follow the general trend.


texts: How to calculate the kinetic order of an enzymatic reaction?

texts:
This question is concerning the metabolism of ethanol by an alcohol dehydrogenase enzyme.

Usually people metabolize alcohol equivalent to "one beer per hour". One beer is said to contain 33cL. The ethanol content of a beer is 4.6%(V/V). If this approximation is correct for an average lean person of 75kg after drinking two beers, then what is the kinetic order of reaction of the enzymatic reaction metabolizing the alcohol?

The alcohol content in one beer is:
$(33 \cdot 0.046)cL = 1.518cL$

The ethanol content in two beers is then:
$(2 \cdot 1.518)cL = 3.036cL$

How do I link this to the weight of the person (the 75 kg)? And how to I determine of this follows a zero, first, or second-order reaction?

I know that a first order reaction is given by the following rate expression:
$-\frac{dA}{dt} = k \cdot A$

The second order reaction is given by the following rate expression:
$-\frac{dA}{dt} = k \cdot A^2$


texts: Accurate way to tell a material is PP with easily available means?

texts:
Sometimes even though certain products that I bought come with a "PP 5" marking on it, I suspect it may not be the case, so I wanna know, is there a relatively safe and accurate way to tell if certain material is really Polypropylene, with easily available appliances or no extra equipment at all?

BTW you can damage and sample so said products.


texts: Wave function for particle in a infinite well located at -L and +L

texts:
The wave function for a particle in a infinite potential well located at $0$ and $L$ is $$\psi_n=\sqrt{\frac2L}\sin\frac{n\pi x}L$$

I want to find our wave function for the same situation where the walls are located at $-L$ and $+L$

I can write the Schrödinger equation, but I am unable to apply the boundary conditions, so I am unable to find the wave function.

How can I find the wave function in case of walls at $-L$ and $+L$?


texts: Is there any emerged master principle in chemistry, like the theory of evolution in biology?

texts:
The question is about emergence and reductionism.

Except for a few exceptions, such as dark matter, most phenomena in Nature could be reproduced from the standard model and general relativity with great accuracy. Up to a Planck scale, there is no inconsistency between general relativity and quantum theory by means of effective theory. However, at different level of complexity, a new principle may emerge. One example is the theory of evolution in Biology.

Is there any similar emerged master theory in Chemistry that comparable with evolution in Biology?

Here, the emerged master theory means:

It is not just a brute-force ab initio computation (emergence). Here I have excluded explicitly correlated Gaussian.
The theory is universally valid. Not like 8- and/or 18-electron principle and/or VSEPR and/or periodic table, we know there are many exceptions.
The theory should generate experimentally testable predictions, hopefully quantitative. Here I have excluded Bader's QTAIM at its current form. Atom in molecule and types of chemical bonds are anyway not observables. One may see some correlation between Laplacian at bond critical point with other molecular properties, and do some fitting or hand-waving argument. Such fitted relation could be useful. However, it is a fitting, not a derivation from its principle. I do not regard it as a prediction.
The theory should not be discovered in condensed matter physics first. Here I have excluded spontaneous symmetry breaking.
I do not expect the statement like, there is no master principle in chemistry is the master principle in chemistry.


texts: Why does spontaneity of a reaction depend on temperature?

texts:
As we know, $$\Delta G=\Delta H - T\,\Delta S.$$
Both in my textbook and on the internet, it was given that temperature was a determining factor in the spontaneity of a reaction. For example, when $\Delta S$ is negative (unfavorable) even then the reaction can still be favorable at lower temperatures.
If $\Delta S = q/T,$ then wouldn't the entropy also decrease by the same factor on decreasing the temperature? In other words, why don't the temperature terms cancel leaving $\Delta G$ independent of temperature?


texts: Why can't terminal alkynes take part in Birch reduction?

texts: According to my book terminal alkynes are not observed in Birch reduction.Why is this so? The only property I know about them is that they are slightly acidic. Does this have something to do with it? Please help me understand this.


texts: Problems with creating sodium hydroxide from sodium (hydrogen) carbonate

texts:
If sodium hydrogen carbonate (baking soda, $\ce{NaHCO3}$) is heated to greater than $50~\mathrm{^\circ C}$, it will release carbon dioxide and water to form sodium carbonate:

$$\ce{2NaHCO3 -> Na2CO3 + H2O + CO2}$$

And when the sodium carbonate is heated further to about $850\ \mathrm{^\circ C}$, it will release more carbon dioxide and form sodium oxide:

$$\ce{Na2CO3 -> Na2O + CO2}$$

And according to Wikipedia:

  Sodium oxide (SOX) is a chemical compound with the formula $\ce{Na2O}$. It is used in ceramics and glasses, though not in a raw form. It is the base anhydride of sodium hydroxide, so when water is added to sodium oxide $\ce{NaOH}$ is produced.

So it should be possible to produce sodium hydroxide from baking soda and water, with some heat. I heated some baking soda in a gas flame. I am not sure exactly what the temperature of the flame was, but it was enough for the stainless steel spoon that I used to glow red. (If it is useful, the gas where I live is approximately $50~\%$ hydrogen, $25~\%$ methane and the rest $\ce{CO2}$ and $\ce{CO}$, and it burns completely with a blue flame. I suspect this flame to be at least $1000\ \mathrm{^\circ C}$, based on available information about flame temperatures of different fuels.)

However, $\ce{NaOH}$ is produced industrially via the chloralkali process, so there must be problems with using this method. What are they, and are they significant if trying to produce a small amount of sodium hydroxide for a minor experiment?


texts: Why does a catalyst increase the forward and reverse reactions equally

texts:
With reference to the picture below, how is it that when there is a lower activation energy (due to the alternate reaction pathway provided by the catalyst) that the catalyst will increase the forward and reverse reactions exactly the same amount.

It only makes intuitive sense that when the $Ea$ is lowered, the forward reaction increases more than the reverse reaction because the decrease was an absolute amount (that is, the same decrease for both forward and reverse) and thus proportionately, the forward $Ea$ has been reduced far more than the reverse $Ea$. So why should the reverse reaction instantly be raised such that it is still equal to the forward reaction (if from equilibrium)?


texts: Calculating ratio of bicarbonate ion to carbonic acid in blood

texts:
For the following reaction, $\ce{K_a} = \pu{4.2e-7}$ :

$\ce{H2CO3(aq) + H2O(l) <=> H3O+(aq) + HCO3-(aq)}$

We're given the pH of blood, which is $7.4$. We need to calculate the ratio ("$X$") of bicarbonate ion to carbonic acid in blood.

I know I need to convert the $\ce{K_a}$ to $\ce{pK_a}$, and did so as follows:

$\ce{pK_a} = -\log(\ce{K_a}) = -\log(\pu{4.2e-7}) = 6.4$

But I'm not sure how to proceed from here. Any help would be greatly appreciated.


texts:
We had a question in a rest comparing the bond lengths of hydrocarbons fluorides, and the answer key says CF3- CF3's supposed to have a longer C-C bond than H3C- CH2--F.

Why is this so? Wouldn't the C-F bond have less s-character, leading to increase in s-character in the other bonds? That way, CF3-CF3 should have the shortest bond length.
Thanks!


texts: My question is pretty simple. Does studying chemical engineering require memorizing manufacturing processes and other complex chemical mechanisms, or does it rely more on the practical side of things focusing on how stuff actually works.


texts: What provides the energy allowing membrane proteins to facilitate diffusion across the membrane?

texts: We know that facilitated diffusion requires no energy.  But the transport proteins, when bind to a molecule from ECF (extra-cellular face) , the proteins rotate and deliver the molecule into ICF (intra-cellular face). Now my question is that--- Which force provides with the torque to rotate and how it works with out energy?


texts: What are some of the simplest chiral molecules in biological systems

texts:
I have understood generally for a while there is a significant preference in "life" for so-called "left-handed" (chiral) molecules, though I'm reading things now that say "life" sugars are right-handed, while "life" amino-acids are left-handed.

I'm wondering: how simple do these molecules get (particularly the molecules that are in intelligent life, if there happen to be any that are exclusive to intelligent life)?


texts: Why is my conclusion inconsistent with the van't Hoff equation?

texts:
Let's say I hypothesize that a graph of $\ln K$ vs. $1/T$ has a slope of $-∆G^\circ/R$ and a $y$-intercept of $0$. I prove it simply:

$$∆G^\circ = -RT\ln K \quad\to\quad \ln K = -\frac{∆G^\circ}{RT}$$

This matches the linear form $y = mx + b$. Thus, plotting $\ln K$ vs. $1/T$ would have a slope $m = -∆G^\circ/R$ and a $y$-intercept $b = 0$.

However, I understand that a van't Hoff plot defines a graph of $\ln K$ vs. $1/T$ to have a slope of $-ΔH^\circ/R$ and a $y$-intercept of $∆S^\circ/R$. It is clear from the relation $∆G^\circ = ∆H^\circ - TΔS^\circ$ that my final equation is thermodynamically equivalent to the van't Hoff equation. I do not disagree that

$$\ln K = -\frac{∆H^\circ}{RT} + \frac{∆S^\circ}{R},$$

but if I were to experimentally measure temperature and calculate the equilibrium constant temperature, why should I expect the y-intercept to be $∆S^\circ/R$ as defined by van't Hoff rather than $0$ as I defined above? Why should I expect the slope to be $-ΔH^\circ/R$ instead of $-ΔG^\circ/R$? What makes the van't Hoff equation match experimentally determined values over the equation $\ln K = -∆G^\circ/(RT)$?


texts:
The complex $\ce{Ni(acac)2}$ is paramagnetic as expected , i.e it has two unpaired electrons giving rise to a magnetic moment of $ \sqrt{8}$ BM but doesn't have the tetrahedral geometry consistent with the CFT assumptions , why ?

well if the above thing is true then what is the actual structure of the complex ? please help !

source: Inorganic Chemistry: Principles of Structure and Reactivity, 4e


texts: Why is pressure correction in Van der Waals equation positive

texts: In real gas, there exist some attraction forces as opposed to what the Kinetic Theory of gases had proposed. Due to attraction, shouldn't the gas molecules strike the walls of container at a lower speed thereby making pressure less than ideal?


texts: When an inert gas is added to a system of constant volume, equilibrium is not effected?

texts: But pressure of the system increases. Because of this increase in pressure, wouldn't (according to Le Chatelier's principal) equilibrium shift towards the side with less moles of gas?


texts: Response factor calculation for gas chromatography

texts:
While dealing with gas chromatography, how do you calculate the response factor with only the area known?

I am given the equation

$${k_1\over k_2} = {f_1 \times O_1 \over f_2 \times O_2}$$

where $O_1 = 21.28$, $O_2 = 178.35$, and $f_1 = 1.00$. $k_1$ and $k_2$ are the weights (in moles) that we added into the mixture. I calculated $0.05\,\mathrm{mol}$ for each component.

Using the formula (above) and the given quantities, I get

$$1 = {1.0 \times 21.28 \over f_2 \times 178.35}$$

Solving for $f_2$, I get 0.119, and I do not believe that is right. Is my approach valid?


texts: How to test a sample of cigarette tobacco for its nicotine content?

texts: I was wondering how one would go about testing samples of different cigarette tobaccos for their nicotine content. Is there a kit of some kind available online to do this?


texts: What happens when a solution of sodium chlorite is acidified?

texts:
I'm told that when sodium chlorite $\ce{(NaClO2)}$ is mixed with aqueous acid, chlorine dioxide ($\ce{ClO2}$) is produced and remains mostly dissolved in water.

I would like to know how the strength of the acid (concentration of acid and/or the type of acid) affects this reaction. I would also like to know what happens (afterwards) to the $\ce{ClO2}$ over time. For example, if undisturbed, does the $\ce{ClO2}$ enter the air, convert into another compound, or something else?


texts: How does carbonic acid cause acid rain when Kb of bicarbonate is greater than Ka?

texts:
How does carbonic acid cause acid rain when $K_b$ of bicarbonate is greater than $K_a$? Should it not create an alkaline solution?

$K_a = 4.8 \times 10^{-11}\ (mol/L)$. $K_b = 2.3 \times 10^{-8}\  (mol/L)$. These are the values for $\ce{HCO3-}$.

These numbers are from a school book that I read, but it's not in English. It's called "Kjemi 1" by Harald Brandt


texts: Is hydrogen bonding generally defined to include only three period two elements?

texts:
Traditionally, hydrogen bonding has been defined to only include interactions between a positively polarized hydrogen and three period-two elements: nitrogen, oxygen, and fluorine.

Why was this definition proposed? A common question is why can't chlorine, by the aforementioned definition, hydrogen bond?

Does this have anything to do with hard and soft acid-base theory? Hydrogen is a hard acid, and chlorine is a comparatively soft base ... and the period two elements are all relatively hard?


texts: How to replicate compositions of discontinued paints?

texts: I am a house painter, over the last 20 years I've noticed that discontinued lines of paint are much better. These paints were vinyl acrylic. Now the vinyl has been removed. I'm wondering if adding 1 ounce of Elmer's glue to 100% acrylic paint would duplicate the old formula? I think the old ingredient was polyvinyl acetate.


texts: Will calcium concentrations be reduced when water is boiled at lower atmospheric pressure?

texts:
It's well documented that one can reduce calcium concentrations in water by boiling the water. This is caused by CO2 being driven out of the water and the calcium precipitating out of solution. Ok, but, would calcium drop out of solution if the water was to reach its boiling point at a lower pressure atmosphere? The goal being energy-savings.

Anyone with some insight on this or ... wielding a low-pressure apparatus and a TDS meter?


texts: How is it that fructose has a different metabolic pathway than glucose but yet glucose is converted to fructose?

texts:
Fructose is described to have a different metabolic pathway (a more fat-inducing one) than glucose (see: http://healthyeating.sfgate.com/difference-between-sucrose-glucose-fructose-8704.html) as it can only be metabolized by the liver and does not impact insulin.

What I don't understand, is that in glycolysis, a paramount step of metabolizing glucose, it is very quickly converted to fructose-6-phosphate. Why does the body want to convert glucose into fructose?


texts: Why can't you have compressed oxygen and nitrogen in the same tank?

texts:
I just watched a movie about the Apollo missions. They wanted an oxygen/nitrogen atmosphere on the spacecraft. But they said it would be too heavy and expensive to use an oxygen tank and a nitrogen tank and also equipment to monitor and control the mix ratio, so they went with pure oxygen. Why couldn't they put oxygen and nitrogen together in one tank at the right ratio so then they would only need one valve to maintain pressure?

Thanks Karl. It's so obvious now that you mention it! Guess I'm too new here and it won't let me reply to your comment.


texts: How many electrons are in the d orbitals of NiCl2·6H2O?

texts:
On Wikipedia, it says that

  $\ce{NiCl2·6H2O}$ consists of separated trans-$\ce{[NiCl2(H2O)4]}$ molecules
  linked more weakly to adjacent water molecules. Only four of the six
  water molecules in the formula are bound to the nickel, and the
  remaining two are water of crystallisation.[4] Cobalt(II) chloride
  hexahydrate has a similar structure.

So nickel chloride hexahydrate has an octahedral symmetry and the ligands are two chloride ions and 4 water molecules? Or is $\ce{NiCl2}$ a solid in water, but separates into $\ce{Ni^2+}$ and $\ce{Cl-}$ ions in water since they are ionic?

Does this also indicate that there are 8 electrons in the $d$ orbitals and that it will form a high-spin complex (I know that the low-spin orbitals look the same though) so that there are two unpaired electrons? I think I'm thrown off by the chloride ions because my textbook only explains complex ions like $\ce{[CoCl4]^4-}$ or $\ce{Fe(CN)6}$ which are easier to understand for me.


texts: Why do we only consider relative motion of hydrogenic atoms?

texts:
In my lectures on quantum mechanics, it was said that the Hamiltonian for a hydrogenic atom could be split into relative motion and translational motion, as follows:

$$\hat{H} = - \frac{\hbar^2}{2m}\nabla^2_{cm} - \frac{\hbar^2}{2\mu}\nabla^2 - \frac{Ze^2}{4\pi\epsilon_0r}$$

and that one only need consider the relative motion:

$$\hat{H} = - \frac{\hbar^2}{2\mu}\nabla^2 - \frac{Ze^2}{4\pi\epsilon_0r}$$

This statement is reiterated in Atkins' Physical Chemistry (10th Edition), as well as his Molecular Quantum Mechanics (4th Edition), and various other online resources, but I am yet to find an explanation as to why.

Why can we, and why do we, neglect the translational motion of the atom?


texts: Why is only one lone pair in imidazole delocalised?

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I was wondering why only one of the nitrogen lone pairs in imidazole is involved in the delocalized π-system. Specifically, I was wondering why it is that lone pair B in particular is delocalized, instead of lone pair A:

Here is my conjecture about why B's lone pair is delocalized while A's lone pair cannot be.

If we delocalize A, we'd get extreme ring strain; we'd make the geometry around that nitrogen $\ce{sp}$. This implies a $120^\circ$ bond angle. That's problematic.
Effective $\unicode[Times]{x3C0}$-orbital overlap (conjugation) only occurs when the p-lobes are planar — i.e. parallel with each other. If the nitrogen with the B lone pair kept its B lone pair, then that nitrogen would be tetrahedral and that would distort the planarity of the molecule; everything else in the molecule appears to be $\ce{sp^2}$ hybridized.
We also run into formal charge issues; we get a positive formal charge on the "A" nitrogen and a negative formal charge on the B nitrogen. While this isn't a dealbreaker, it's not preferable, as there is separation of like formal charges.
Anything I miss? Any points I mangled?


texts: Atoms or molecules with spin 1 in the ground state?

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Is there any atom or molecule that has spin 1 in its ground state?

Do Hund's rules keep this from happening for an atom?

The reason I'm curious is that it would be nice to have a spin-1 example for use in pedagogical discussions of the Stern-Gerlach experiment.

[EDIT] Clarification: when I say "spin," I mean the total angular momentum, not just the sum of the spin-1/2's. (The total angular momentum is what you are seeing in the Stern-Gerlach experiment.) I deleted the part of the question about ions, because, as pointed out by Orthocresol, they won't be usable in a normal Stern-Gerlach spectrometer.


texts: Why is the enthalpy of solution for NaCl 3.88 and not 4.1 kJ/mol?

texts:
Based on Hess' law, the molar enthalpy of solution is equal to the sum of the enthalpies of formation of products minus reactants. In the case of dissolving table salt ($\ce{NaCl}$) in water, those reactants are $\ce{NaCl (s), Na+ (aq)}$, and $\ce{Cl- (aq)}$, with enthalpies for formation of $-411.2$, $-239.7$, and $-167.4\ \mathrm{kJ/mol}$, respectively.

So, based on Hess' law, the enthalpy of solution should be $4.1\ \mathrm{kJ/mol}$. However, the actual enthalpy of solution in this case is $3.88\ \mathrm{kJ/mol}$ according to multiple sources. The discrepancy appears to be that the enthalpies of formation for $\ce{Na+}$ and $\ce{Cl-}$ don't exactly equal the combined enthalpy of formation for $\ce{NaCl (aq)}$.

I am at loss for why there is this small offset. Is it due to only partial dissociation of $\ce{NaCl (aq)}$ while in solution? And, if so, wouldn't that have a larger effect? Or is the effect slight because there are some inter-molecular forces at play that only minimally affect the total enthalpy of solution? It could be that my numbers are wrong, but a cursory search on the internet matches the values for $\ce{Na+}$ and $\ce{Cl-}$ in the textbook I have on hand.


texts: how does electronic conductance of a metal change with density?

texts: The electronic conductance of a metal depends on its density.Does this mean that if we increase the density of the metal,its electronic conductance will increase?How does it happen?


texts: When an acid is added to water, why does the hydroxide ion concentration decrease?

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At equilibrium in pure water, we have
$$\ce{[H_3O+][OH-]} = 10^{-14}$$

Since $\ce{H3O+}$ and $\ce{OH-}$ ions are produced in pairs, we may conclude
$$\ce{[H_3O+]}=\ce{[OH-]} = 10^{-7}$$

So far so good. But shouldn't things change when we introduce a new substance into water ? I mean why does the first equation above hold no matter what ?

Also when I introduce $\ce{H2SO4}$ into the water, it doesn't just give a $\ce{H+}$ ion, it also gives $\ce{HSO4-}$ ion. Shouldn't these new negative ions change the behavior of water? Why does my textbook never talk about these new negative ions? Help appreciated. Thanks!


texts: While fermenting my rum wort (what rum is called before it is distilled) in a plastic fermentation barrel, I noticed little blue flashes appearing over the surface of the liquid. Any idea what could have caused this? I have looked around and the closest thing I could find is triboluminescence, but that doesn't sound right to me...


texts: Why do some chemical reactions require many steps?

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I was a college student of physics ten years ago, and recently started to learn biochemistry. I enjoy finding out that some familiar concepts in physics play important roles in biochemistry such as Entropy and Gibbs free energy.

For example, as a (ex-)student of physics, I am happy to know that Gibbs free energy helps to decide the directions of chemnical reactions. I feel this is a good example where a sort of fundamental law of physics determines how phenomenon looks like.

However, I still can not understand why the chemical reactions in a body need to be so complex. Many chemnical systems consists of more than several steps to acheive their purposes. According to wikipedia, glycolysis takes ten steps through its process. Why so many steps are necessary?

I tried to find out a physical law which prohibit that glycolysis process is achieved by one or two steps. But I could not find an answer.

I would like to know (or discuss) whether there is a physical law which makes the chemical system such a complex one (many steps required).

My assumption is that some physical law prohibit the existence of a enzyme which realize a one-step process of glycolysis.