texts:
I recently answered a question about Breaking Bad's initial methamphetamine production method (i.e. the reduction of (pseudo)ephedrine). The reaction is as follows:

(Source)

It is infamously known as the $\ce{HI/P}$ reduction and was (and still is somewhat) a real plague in the United States until cough medicine containing ephedrine came under tightened control. That for an introduction, now the question: what is actually the reaction mechanism of the $\ce{HI/P}$ reduction?

The first step seems like a simple $\ce{S_{N}2}$ substitution of $\ce{I^{-}}$, catalyzed by the protonation of the alcohol group by hydroiodic acid (making it a far better leaving group). But what is the mechanism after that? How is phosphorus involved? Does the $\ce{HI/P}$ reduction have any legal use?


texts: Can a reverse osmosis system remove radioactive elements in contaminated water?

texts: I am curious to know if a reverse osmosis system can clean water from radioactive elements like cesium-134 and cesium-137. If it can, how efficient can it be?


texts: Has a non-carbon-based form of life been discovered since 2010?

texts:
In 2010 NASA announced the discovery of microorganisms that, after being treated in laboratory, could keep growing only using arsenic, instead of the (though very small amount of) phosphate they also had in nature.
However, this was confuted by further studies in the following two years.
Has there been success in finding "alien" life on Earth, somewhere else, since then?

Edit: the NASA article from back then says what gilleain sais below. I naively hoped a couple of articles from different (not scientific, but not bad) journals were not modifying the facts. Thus the question actually is if non-carbon-based life has been found.


texts: AP Chem Question about Reaction Rate - Confused?

texts:
I found this question in the AP Chem book, and I understand why B is the answer (as the answer key says). However, I don't understand why D is not also correct.

The question is:

A multistep reaction takes place with the following elementary steps.

Step I. A + B <-> C
Step II. C + A -> D
Step III. C + D -> B + E

Why would increasing the temperature make the reaction rate go up?

(A) it is an endothermic reaction that needs an outside energy source
to function
(B) The various molecules in the reactions will move faster and
collide more often
(C) The overall activation energy of the rxn will be lowered
(D) A higher fraction of molecules will have the same activation
energy

I understand that B is correct based on collision theory, but why isn't D correct as well? Don't a greater % of molecules have the same activation energy at higher temperatures? (Or am I misinterpreting answer choice D?)

Thank you!


texts:
How to determine which compound will get oxidised and which will  be reduced in a cross cannizzaro reaction?

As a general rule of thumb, I have always been told that Formaldehyde is always oxidised, and the other is reduced.

But no general principle was ever given to me. What factors (eg electronic, steric, etc) affect this ??

There is this question already here, but the both the answers seems to be contradictory. @Jan says , the one with more hydrate forming tendancy oxidised , whereas
@RE60K says less Nucleophilic aldehyde oxidises (which I believe will have a lesser tendancy to form hydrates)


texts: What's the exact difference between (-)-BTX and (+)-BTX

texts:
I quite liked this article, which describes the synthesis of (-)-batrachotoxin as well as a steroisomer, (+)-batrachotoxin. I would like to know what the precise difference is between the two: are they precise mirror images of each other, or is there something more subtle going on? Is there something specific about the (±) notation (as opposed to S and R, for example) with relevance to the difference between the two?

I had a look online but the original paper is thin on structures that I can understand, and just going on google buries me under a slew of (-)-BTX results.


texts: Boiling points of Hydroxylamine and water

texts: Why does $\ce{NH2OH}$ have a lower boiling point than water? According to Wikipedia, hydroxyamine has a boiling point of 58 °C. Could this be due to the extent of hydrogen bonding among both molecules?


texts: Do the spectra of compound materials combine linearly with respect to the ratios of the constituent compound spectra?

texts:
My question stems from reading this article on the FTIR spectrum of oil that has been mixed with various contaminants.

If one has the spectrum for the original uncontaminated oil and the spectrum for water, will the spectrum of a sample that has been contaminated with 10% water (by weight) be equivalent to the addition of original oil sample spectrum and 0.1 of the water spectrum intensities?

(Also, should the unit of contamination be the weight or the volume?)


texts: Decarboxylation product of bicyclic compound

texts:
What is the decarboxylation product of the following species:

It may seem straightforward but the product enolate involves a double bond with one end at the bridgehead carbon which is impossible/very unstable. What is the correct product and how is the product reached mechanistically.


texts: Compounds forming between silicon gallium and nitrogen

texts: What are the possible compounds that can form between silicon, gallium and nitrogen?


texts: What will be the product ratio if I do chlorination of p-toluic acid?

texts:
If I do chlorination of p-toluic acid using Lewis catalyst, e.g. $\ce{FeCl3},$ what will be the ratio of major product to side product? Main product shall be 3-chloro-p-toluic acid and other product may be 2-chloro-p-toluic acid for monochlorination.

So, what will be approx ratio of these two?


texts: How can I estimate how much humidity is present in a NaOH granulate?

texts:
I have a container with NaOH granulate. I want to use it for making soap again, as I did in the past.

When I checked it I saw big clumps because the seal was not good and humidity got in since last time. Yesterday I used it anyway, increasing the amount arbitrarily by 10%, and still was not enough.

I have the following tools:

scale (sensitivity 1 gram),
arbitrary glass or plastic volume meter calibrated with said scale,
temperature probe (up to 70C with 0.5C tolerance and 0.1C sensitivity),
white vinegar,
concentrated lemon juice,
concentrated HCl (I think 36%).

More common "kitchen" chemicals may be available, if you ask in the comments.

How can I estimate how much humidity is present in the NaOH granulate using household items/chemicals?

A measurement performed directly on the NaOH solution used for the soap (around 300 g NaOH and 750 g water) is acceptable.


texts: Dehydration of secondary alcohol via E1 mechanism

texts:
Write the mechanism for this reaction:

I am trying to do a dehydration of an alcohol using the reagents sulfuric acid and acetic acid. I don't know how I am supposed to use the acetic acid, instead I've been using water. This is my proposed mechanism:

But it doesn't include the acetic acid, and it doesn't say in the question whether it is done in solution with water or not but I only know how to do it with $\ce{H2O}$. My main issue is that I need to put the acetic acid into the mechanism.


texts: What is the chemical equation for a Maillard reaction?

texts: I'm a 10th-grader in my first year of chemistry.  We have an assignment to make a brochure about a certain reaction, and I'm studying Maillard reactions.  Does anyone know the chemical equation involved in the reaction?  All I find online are images that I've yet to learn how to read.


texts: Can I test for lead with household chemicals?

texts:
I picked up a metal fence loop cap today and took it home just because I liked the shape.

(^ not mine)
I cleaned it, but some of the paint is chipping off. I'm only vaguely thinking about lead, and I'm not going to chew on it, so I don't want to buy a test kit. Is there a way I could test for the presence of lead ions with common/ideally household chemicals? I'd be willing to wait until I'm at my school lab again if I needed HCl or something.


texts:
Is the mass of electrons covered when talking about atomic mass. For example, the mass of Carbon is $12.011\space\text{amu}$. If this is including the mass of electrons (assuming the atom is neutral) the nucleus' mass is $12.011-6(\frac{1}{1840})=12.00773913$

The reason I need to know is I'm studying mass defect in relation to protons and neutron. If I inadvertently include electrons in my calculation, my binding energy will also be wrong.


texts: Egg-Detection in Pastries: An Analysis in Heat-Alterated Molecule Identification

texts: I would like to know if anybody here knows of a method to detect the presence of ovalbumin--or any unique, egg-related molecule, in a baked good. Here I am anticipating that the "unique egg-related molecule" might alter under high temperatures, and so the suspect molecule for detection may or may not be any molecule which is present in a fresh, uncooked egg. I'm thinking of something that can be brushed on to a pastry to evolve a color change. Any help is appreciated.


texts:
Free silicon is not found in nature (in water, it might be present in the form $\ce{Si(OH)_{4}}$. Some compounds of silicon, such as silane ($\ce{SiH_{4}}$) will react spontaneously in an aqueous environment, while the analogous methane won't.

Is there an explanation for the tendency of silicon compounds to react with water?


texts: How do I go about balancing these equations?

texts:
I have to use oxidization number approach.

$\ce{Co^2+ (aq) + H2SO3(aq) -> Co^3+(aq) + S2O3^2- (aq)}$

This is my approach so far:

The change in Co is 1 electron, the change is S is 2 electrons, so CO must be multiplied by two

$\ce{2 Co^2 + H2SO3(aq) -> 2 Co^3+ + S2O3^2-}$

I balance the O's, then balance the H's and I get

$\ce{2 Co^2+ + 2H2SO3(aq) + 2H^+ -> 2 Co^3+ + S2O3^2- + 3H2O(l)}$

I did it the half reaction way as well, I got the same answer but the coefficients on the Co's were 4. I suspect my problem is my assumptions about the oxidization number change at the beginning.

Thanks in advance


texts: Calculate work done by burning benzoic acid exposed to the free air

texts:
I'm self-studying and can't solve this problem in Ball's Physical Chemistry. Now, the errata shows that the answer in the book is not correct; still, I can not make sense of it.

$(2.55)$ Benzoic acid, $\ce{C_6H_5COOH}$, is a common standard used in bomb calorimeters, which maintain a constant volume. If $1.20\text{g}$ of benzoic acid gives off $31,723\text{J}$ of energy when burned in the presence of excess oxygen at a constant temperature of $24.6^\circ\text{C}$, calculate $q, w, \Delta H,$ and $\Delta U$ for the reaction.
$(2.56)$ $1.20\text{g}$ of benzoic acid, $\ce{C_6H_5COOH}$, is burned in a porcelain dish exposed to the air. If $31,723\text{J}$ of energy is given off and the system temperature is $24.6^\circ\text{C}$, calculate $q, w, \Delta H, $ and $\Delta U$.

The answers(corrected from errata) are,

$(2.55)$ $q = -31,723\text{J}, \Delta U = -31,723\text{J}, w = 0, \Delta H = -31,735\text{J}$
$(2.56)$ $q = -31,723\text{J}, \Delta H = -31,723\text{J}, w = 12, \Delta U = -31,711\text{J}$

The book never talks about heats of combustion prior. Computing using a value I found on the internet of $26.4 \,\text{kJ}/\text{g}$, I get a value for $q$, I get that $\Delta U = q + w$ then and we can solve for work. This seems to be an incorrect approach since the energy given off as heat seems to already be given.
Why is the enthalpy the same as the heat in the second case? I would assume it is because the pressure is constant, but only the external is constant, which is not what is used to determine that enthalpy is the same as heat.
Where does this work come from? The volume changes in the non-calorimeter experiment, so work on the acid is done. But how does on obtain this change?
How do I solve this problem correctly?


texts: Spontaneity of reversible chemical reactions - Both sides?

texts: Does the reversibility of a chemical reaction make it spontaneous from both sides also? (i.e.: forward & backward reactions) If not then is there any relationship between $\Delta G$ of forward and backward reactions. Am I right to assume that if $\Delta G$ of one of the process is positive then $\Delta G$ for the reverse process must be negative. So at equilibrium $\Delta G = 0$ ?


texts: Does Glycerol give silver mirror test with Tollen's Reagent?

texts:
I did an experiment in my school lab in which we had to identify the given organic compound. In my Lab Manual, it's written:

  Take 2 ml of Tollen's Reagent and add a few drops of organic sample. Heat the contents on boiling water bath for 5 minutes. Silver Mirror is formed. The given organic compound is Glycerol.

As far as I know, the compounds with aldehyde groups in them give silver mirror. Also those which contain $\alpha$,$\beta$-hydroxy ketone are known to react with Tollen's Reagent. I have never heard of Glycerol reacting with it. I searched but couldn't find this thread anywhere. Though I found that on heating Glycerol, it gives us Acrolein which does contain aldehyde group, which I think is the reason but I am not sure.


texts: Is there an algorithm for ascertaining the relative size of an atomic/ionic radius?

texts:
To the best of my knowledge, the following properties affect atomic radius.

The grounded-state size of the valence electron shell.
The Coulomb force of the core electrons less the Coulomb force of the protons.
The number of electrons in the valence shell.
Whether an electron#-proton# imbalance is sufficient to change the size of the valence electron shell.

Question 1. Are there any other factors that I should know for Chem. 101?

Question 2. If I were to estimate the size of an atom's radius relative to the radii of the atoms described on the periodic table, I would proceed thus:

1st: Ascertain the grounded-state size of the valence electron shell (i.e. the row of the element in the periodic table).

2nd: If the thing in question is an ion, then adjust the number of electrons accordingly.

3rd: If the adjustment in the second step removed, or added, enough electrons to the atom to eliminate the valence energy shell, or to create a new valence electron shell, then adjust the electron configuration accordingly.

Steps 1-3 give the size of the electron shell, and so give the period that comprises the atoms most comparable by radius size.

4th. For the atom/ion under consideration, and for each element listed in the relevant period, subtract the Coulomb force of the protons from the Coulomb force of the core electrons. The lesser the value of the difference the smaller the size of the atomic radius.

5th. If steps 1-4 produce the same value for the atomic radii of the atom/ion under consideration and for one or more of the relevant elements, then the largest atomic radius characterizes the comparate whose valence electron shell comprises the most electrons.

Is that correct?


texts: Ramachandran plot Phi(ϕ) Psi(ψ) dihedral angle Convention for Zero, Positive and Negative value- old and new

texts:
Update: possible duplicate: What is the precise definition of Ramachandran angles?. Question modified.
G.N. Ramachandran et al, in their own work (PMC) (DOI), did not used phi(ϕ) and psi(ψ) as we use today. They used phi(ϕ) and phi-dash(ϕ') defined as follows:

The conventions we have adopted for the standard configuration ϕ = ϕ' = 0°) and for the positive sense of rotation for the two angular parameters ϕ and ϕ' are indicated in Fig. 1.

Where Fig. 1 is:

Also they had adapted a very different values, 0 to 360 degrees for ϕ and ϕ'. They provided the Ramachandran plot like this:

This looks very different from the Ramachandran plot we see nowadays because:

This (Ramachandran's original) graph looks flipped from todays.

The zero degrees value of present day is perhaps different from Ramachandran's Zero degrees. Because the current day zero degree correspond to Ramachandran's 180 degree (of original graph).

So my question is basically:
On todays convention; how we define the zero value, positive value and negative values of phi and psi dihedral angle? and how does the new and old convention relate?
Prior research:
I did not find anything on intensive internet search. I got one graphic without any reference

I am doubtful about this diagram because its Zero degrees seem to be the zero degree of Ramachandran's original plot.
Many thanks in advance
Update: As the user @Buck Thom said

The meaning of angles with value of zero is the same.

But sill I looked both old and new graph and found what is labelled as 0 degrees in the new graph, has been labelled as 180 degrees in the old graph as follows


texts: In my book it 's stated that the bond order of the oxy acids increases with increasing value of $n$ in $\ce{HClO_n}$ , and also the energy required to break $\ce{Cl-O}$ bond decreases with increasing n leading to the greater strength in acidity . But with increasing bond order bond length should decrease making it tougher for it to break the $\ce{Cl-O}$ bond, so how's that possible?


texts: What is the effect of substituting oxygen with sulfur in drug molecules?

texts:
What sort of changes in the properties of organic or drug molecules can be anticipated if you substitute some or all of the oxygen atoms with sulfur atoms, and vice versa.

My interest in this question is for chemical graph theory perspective. There are numerous parameters calculated on molecular graphs (in trying to relate to chemical or biological activity) which are indifferent to the above substitution. I would like to make an appropriate adjustment if the effects are really significant.


texts:
We were doing a titration experiment to find out how much ascorbic acid a vitamin pill actually contains. In a flask, there is a solution of water, sulfuric acid, potassium iodide and ascorbic acid. Also starch as an indicator. When adding potassium iodate $(\text{KIO}_3)$, the following reactions will appear:

$$\text{IO}_3^- + 5 \ \text{I}^- + 6 \ \text{H}^+ \longrightarrow 3 \ \text{I}_2 + 3 \ \text{H}_2\text{O}$$

After the iodine is formed, the following reaction will appear:

$$\text{C}_6\text{H}_8\text{O}_6 + \ \text{I}_2 \longrightarrow \text{C}_6\text{H}_6\text{O}_6 + 2\ \text{H}^+ + 2 \ \text{I}^-$$

After using the right amount of potassium iodate, there will be no ascorbic acid anymore, causing to eliminate the second reaction. When there is no ascorbic acid, iodine will not react back to iodine-ions, which causes the starch to give a brown/blue color.

My question is, why isn't this possible without the sulfuric acid?


texts: Crystallization of solutions and liquids

texts: The process of crystallization of a liquid or any solute occurs when its concentration exceeds the maximum concentration which the solvent can carry or when the temperature drops below the freezing temperature in cases of liquids. Then why is it that these materials require a small "nuclei" or a jagged edge to start forming crystal on, why cant it form crystal anywhere within the bulk of the matter. (eg cloud formation from condensation of water)


texts:
I am trying to name the following compound:

I thought the name would be: (E)-3-[(4-methylphenyl)methylideneamino]benzoic acid

I stayed away from benzylidene since P-57.1.2 indicates no substitution on this preferred prefix. However, Chemdraw shows the name as: (E)-3-((4-methylbenzylidene)amino)benzoic acid

Is my Chemdraw outdated? If so, is my name correct or is there a better way to name this compound? I am also a bit confused as to when to use parenthesis, brackets, or braces with substituent names, am I using them correctly? If not, why? Also should it be "amino" or "aza", I am confused as to when to use one or the other (similar to "oxa" vs "oxo", I think; unrelated but I also don't get the difference between those).


texts: What makes the cyclic structure of glucose more stable than the open chain structure?

texts: Is it tautomerism? Or some other factors involved?


texts: Are the elements lanthanum and actinium considered to be in the d block or the f block of the periodic table?

texts:
Many periodic tables place lanthanum and actinium in the f-block of elements, for example, this periodic table from Los Alamos National Laboratory.

However, this table from the Royal Society of Chemsitry places lanthanum and actinium in the d-block.

Which is the most appropriate placement of these two elements on the periodic table? What is the most recent scientific consensus regarding this matter?


texts: Spontaneous explosion of a bottle containing alcohol and milk

texts:
A friend of mine gave me a bottle of home-made liquor which is a concoction of pure alcohol and sweetened milk. I accepted his gift happily and then I put the bottle in my cocktail cabinet. After an hour, we happened to hear a terrible noise of a some sort of explosion. We were indeed right - the bottle had exploded with actually no reason! Could someone please explain this strange phenomenon?

I am not sure whether this is important but he claims he had been keeping it in his fridge, although the difference of temperatures (in the fridge and in the cocktail cabinet) does not seem terribly significant to me. Also, the bottle was almost full meaning there was little room for the air in the bottle.

Please find attached the full list of ingredients:

0.5 litre of condensed, unsweetened milk,
0.5 litre of condensed, sweetened milk,
0.25 litre of pure alcohol,
few sweets.


texts: How to prevent petrol from being flammable?

texts:
Is there any way to prevent petrol from being flammable without losing it's solvent properties? Preferably some affordable way that is applicable for DIY.
In my case, petrol is used for bearing cleaning, and there is a risk of inflammation due to accidental spark.

If no affordable way exists, what octane number is safer (less flammable)?


texts:
My attempt:
polar protic solvent, low temp, tertiary carbon, and a weak (?) nucleophile and a weak base.

It seems like this is a pretty standard SN1 reaction so "I and II" would be the correct answer?


texts: What is the velocity of an ejected electron in lithium when subjected to UV radiation?

texts:
If UV radiation strikes an atom of lithium with one electron in its lowest allowed energy state with enough energy to eject the electron from orbit, what is the electron's velocity upon ejection? The wavelength is 7.1 * 10^-9 meters.

If this was hydrogen, I would use the fact that the energy of the radiation is the sum of the binding energy and kinetic energy of the electron, but the conditions are for lithium. How would I solve this problem given that it's lithium and not hydrogen?


texts: What drives the cost of Raman spectroscopy?

texts:
Raman spectroscopy setups are quite expensive- \$10-\$30k seems pretty common. The spectrometer, the probe/fiber cable, and the laser are typically each $3k+.

The spectrometer could potentially be replaced by an absorption spectrometer. The probe/fiber cable could potentially be replaced by free space optics. The Raman-specific laser could potentially be replaced by a cheaper laser. These components can be had for hundreds of dollars instead of tens of thousands.

Some potential negative effects I can imagine from swapping these out are:

Increased integration times
Decreased spectral resolution, or wider peaks
Decreased signal to noise ratio
Increased maintenance
Shorter lifetime

My broad question which I hope will be generally useful is, which of these components can be replaced with cheaper options with what effect?

My specific question, which may be less generally helpful, is which components should I get cheaper if I only care about signal-to-noise ratio and not integration time or peak width?


texts: Mercury assisted deprotection of dithiane

texts:
1,3 dithianes are used in umpolung reactions and can be deprotected by mercury containing compounds - but could anyone help explain what the exact mechanism is? Many texts seem to skim over this by explaining it is similar to acetal hydrolysis, but I'd really like a more detailed explanation as to the role of the compounds. A reaction I have seen involves $\ce{HgO}$, $\ce{HgCl2}$, $\ce{CH3CN}$ and $\ce{H2O}$. If it is similar to acetal hydrolysis, the $\ce{H2O}$ is probably to complete the final step of attacking the $\ce{S=H}$ bond, but what about the initial step?

I am assuming one sulfur atom forms a bond to the $\ce{Hg}$, but which Hg compound would it be in this case, the $\ce{HgO}$ or the $\ce{HgCl2}$? What is the role of the $\ce{CH3CN}$ in this case? Thanks!


texts: Can acid concentration be determined from Ka values in a titration?

texts:
Say I have a sample of vinegar and I want to find the concentration of ethanoic acid in it. So I perform a titration using a $\mathrm{pH}$ meter, and using that data I can draw a $\mathrm{pH}$ curve and find quantities such as the initial $\mathrm{pH}$, the half-equivalence point, the equivalence point, and the $\mathrm{pH}$ at the equivalence point.

I feel like my teacher hasn't explained this very clearly, but given the $K_{\mathrm a}$ value for ethanoic acid and the data collected from the titration, is it possible to determine the initial concentration? If so, how do I proceed?

(I'm aware of the simple stoichiometric method, just curious whether this approach will work.)


texts:
Does NaCl reduce the surface tension of water? And why?

For example soap does it, and I was wondering if NaCl does the same.


texts:
Have the shapes of synthesized anthropomorphic molecules (nanoputians) been verified experimentally?

X-ray diffraction, atomic force microscopy imaging of single molecules, anything?

I was tempted to use the title Has anyone ever seen a nanoputian?

Edit: The IBM video World's Smallest Movie is not of a molecule, but it does contain an anthropomorphic shape built from individual atoms, visualized at atomic resolution using scanning atomic force microscopy.

below x2: Simple illustration of AFM imaging of organic molecule shape. From here. For more recent experiments and videos, see 30 years of atomic force microscopy: IBM scientists trigger and observe Reactions in an individual molecule and also IBM & Warwick Image Highly Reactive Triangular Molecule for the First Time.

below: Lewis structure of a nanoputian; "Chemical structure of 2-(2,5-bis(3,3-dimethylbut-1-ynyl)-4-(2-(3,5-di(pent-1-ynyl)phenyl)ethynyl)phenyl)-1,3-dioxolane." From here.

below: Lewis structure of a nanoputian; "Ball-and-stick model of the nanoputian molecule, also known as nanokid, an synthetic compound whose molecules are human-shaped." From here.


texts:
This answer to a now closed question says that ozone gas has a "slight blue" color. But there are lots of blue colors: sky blue, ultramarine, phthalo blue, many others — what is closer to the color of ozone?

This page shows photos of ozone solutions in water, like the one below, but this may not be representative of the color of the gas.

 (source)

So, what exactly color does ozone gas have? Is it a single hue, or does it change depending on concentration/amount of ozone?


texts: How do I prepare 2-(3-azido-3-oxopropoxy)ethyl methacrylate from methacrylic acid?

texts:
I am having some trouble finding a proper synthesis route for the following product.

Originally, I was thinking of reacting methacrylic acid with a large excess of ethylene glycol (along with an acid catalyst), in accordance with Fischer esterification, to obtain the following structure.

I subsequently thought of reacting a base such as sodium hydride, NaH, with the alcohol group (removing its 'H') in the hopes of connecting it to the other fragment, which I thought would contain an alkyl halide. However, I was unsure how realistic this step might be due to the following concern: couldn't the hydride ion, which is a very strong base, attack the ester group instead of the alcohol (despite the alcohol having the lower pKa of the two groups)?
To get around this, I attempted a synthesis, pictured below, starting from ethylene glycol. My main concern with this, however, is the potential for intramolecular Fischer esterification instead of, as depicted, the esterification taking place through methacrylic acid and the acid catalyst (e.g., HCl). How valid is this concern? Additionally, please identify any mistakes I may have made in my synthesis and suggest improvements, even if you have a different synthesis route in mind.


texts: Since BF3 has the shape of tetrahedral, and in the provided solution, Boron is sp2, why is Fluorine sp3 hybridized?


texts:
I'm going to use aluminium in my example, but this is applicable to all metals.

Aluminium has delocalised electrons. It has aluminium cation -electron attraction. It's easier to visualize the atomic structure of aluminium in solid form.

But if it's in the gas phase, will delocalised electrons return to the atom itself, or is there going to be an electron and cation mixture (electrons floating around)?

So can aluminium (or any other metal) conduct electricity as a vapour, and what would its conductance be compared to its solid form?


texts: The particle in a two-dimensional box model and graphene

texts:
I have been having trouble with understanding and solving the following problem.

For two-dimensional conjugated systems, we may use the particle in a two-dimensional box model. In this case the total energy can be written as follows:
$$E_{n_1,n_2} = \frac{h^2}{8m} \left( \frac{n^2_1}{L^2_1}+\frac{n^2_2}{L^2_2} \right)$$
where $L_1$ and $L_2$ are the lengths and $n_1$ and $n_2$ are the quantum numbers of the first and second dimensions, respectively, $m$ is the mass of the particle and $h$ is the Planck constant.
Graphene is a sheet of carbon atoms in the form of a two-dimensional hexagonal lattice in which one atom forms each vertex.

The distance between two adjacent carbons in the hexagonal 6-carbon unit is approximately $1.4$ Å. For a square shaped graphene sheet with $L_1$ = $L_2$ = $11$ Å:
1) Calculate the number of electrons in a ($11$ Å $×$ $11$ Å) sheet of graphene. For this problem you may ignore edge electrons.
2) Calculate the energy of the HOMO.
3) Calculate the energy of the LUMO.

For the first question, I simply divided the area of the graphene sheet by the area of a hexagon shaped graphene unit. This resulted in approximately 24 units, which means  there is a total of 48 carbon atoms, since each unit contributes 2 carbon atoms. Therefore there would be a total of 288 electrons in the sheet (from multiplying 48 by 6, since each carbon atom has 6 electrons).
In case this is right, I don't know how to go about calculating the HOMO and LUMO energies. I'm having a bit trouble understanding the quantum numbers in the formula given above: I don't know what the values of the quantum numbers should be when calculating the HOMO or LUMO energy. I do understand how the quantum numbers combinations and energy are related, but I don't know, which specific combinations are used when calculating the HOMO and LUMO energies.


texts: Is aqueous medium necessary for complex formation? if so, why?

texts:
If dry ammonia gas is passed through anhydrous copper sulfate, will it turn blue (due to the formation of tetraamminecopper(II) complex)? Or will silver chloride form diamminesilver(I) complex in liquid ammonia?

If the above complexes do not get formed in non-aqueous mediums, why is it so?


texts: Thermochemical data for thiocyanatoiron(III) ion

texts:
I am currently writing a lab report about the formation constant of $\ce{FeSCN^2+}.$ All I could find online was a formation constant at $\pu{25 °C}$ $(890),$ which was 70% higher than the experimentally measured value at $\pu{21.7 °C}$ $(292).$

I was hoping to use van't Hoff's equation to calculate the accepted value at $\pu{21.7 °C},$ and I found enthalpies and entropies of formation for $\ce{Fe^3+(aq)}$ and $\ce{SCN-(aq)},$ but nothing for $\ce{FeSCN^2+},$ so I can't calculate the enthalpy or entropy of reaction.

Does anyone have a credible source for this data?


texts:
On an exam in organic chemistry I was asked why the reaction B proceeds faster than reaction A.

I answered that: in reaction B, I- is a better leaving group than Cl-, the reason being it is a weaker base.

The answer our teacher gave after correcting the exam was:
I- is a good nucleophile and at the same time a good leaving group.

I scored 1,5p/2p for my answer.

Are the two answers very different or is there some incorrect information in mine?


texts:
Chapter 4, problem 13 from the Chemical Priciples [1, p. 170]:

Equilibrium concentrations
Experiments have shown that at $\pu{60 °C}$ and $\pu{1 atm}$ total pressure, the equilibrium ratio of $\ce{NO2}$ to $\ce{N2O4}$ in moles in a closed vessel is exactly $2:1$.
a) Calculate the equilibrium constant, $K_\mathrm{c}$, for the dissociation of $1$ mole of $\ce{N2O4}$ into $2$ moles of $\ce{NO2}$.

My answer:
The chemical equation is $\ce{N2O4 <=> 2 NO2}$ and at equilibrium the ratio is $2:1$ so shouldn't
$$K_\mathrm{c} = \frac{[\ce{NO2}]^2}{[\ce{N2O4}]} = \frac{(\pu{2 mol L-1})^2}{\pu{1 mol L-1}} = \pu{4 mol L-1}?$$
The answer in the back of the text book is $K_\mathrm{c}= \pu{0.0488 mol L-1}$.
I do not understand how this answer was calculated from the information provided.
References

Dickerson, R. E.; Gray, H. B.; Haight, G. P. Chemical Principles, 3d ed.; Benjamin/Cummings Pub. Co: Menlo Park, California, 1979. ISBN-13: 978-0-8053-2398-6.


texts: Why does the addition of oxygen render materials colourless?

texts:
In our book, it is mentioned that $\ce{H2O2}$ (hydrogen peroxide) is used as a bleaching agent because of its oxidizing nature:
\begin{align}
  \ce{H2O2 &-> H2O + [O]}\\
 \ce{\text{coloured material} + [O] &-> \text{colourless material}}
\end{align}

Why does the second equation happen? In other words, what role does oxygen play in the absorption of light here?


texts: Potential energy difference with different force fields

texts:
I am modeling a simple 2D Graphitic Carbon Nitride (g-C3N4) nanosheet with 54 atoms. I used several force fields with both LAMMPS and GROMACS and the potential energies of the system in npt at 1K and 1 atmosphere are:

LAMMPS using ffield.reax.CHOSFCl = -6,024 Kcal/mol
LAMMPS using tersoff = -7,148 Kcal/mol
LAMMPS using ATB server - gromos54a7 forcefield = -270 Kcal/mol
GROMACS: using ATB server - gromos54a7 forcefield = -228 Kcal/mol

We know that the zero for potential energy is not the same for all the force fields but is it usual to be an order of magnitude difference between REAX and GROMOS force fields?
P.S. All the force fields were recommended and used by the literature for the g-C3N4.


texts:
I have never before heard/read about something as a $sp^5$ hybridization. Today, Henry Rzepa's blog post made me aware of the existance of such a bonding system. That made me search a little bit and I found an entry in a german chemistry forum, where this question was also asked ... they answered it with a mathematical construction$^\ast$:

  Cyclopropane has the following angles:

  $\angle \ce{HCH}=118^\circ~\text{resp.}~\gg 120^\circ$
  $\angle \ce{CCC}~\text{with bent bonds:}~60 + 2 \cdot 21 = 102^\circ$

  The orbitals towards the protons are $sp^2$ because of the $120^\circ$ angles.
   The orbitals towards the carbons originate in the following relation:

  $$1 + a \cos~\alpha = 0$$ ... where $\alpha$ is the bond angle and $a$ is the p-amount in sp$^a$ for the orbitals, which make up the angle.

  This means for the orbitals, which span the 102 degree angle: $$1 + a \cos 102^\circ = 0$$ $$1 + a \cdot (-0.20) = 0$$ $$a = \frac{-1}{-0.20} = 5$$
  $$\Rightarrow \text{sp}^5 \text{-orbitals}$$

  Test:

  In a single sp$^a$ orbital, the s-amount is: $\frac{1}{1+a}$, because $1+a$ equals the sum of all amounts of s and p
  In a single sp$^a$ orbital, the p-amount is: $\frac{a}{1+a}$
  For s:

  In the orbitals that are oriented towards the protons, the s-amount is $\frac{1}{1+2} = \frac{1}{3}$
  In the orbitals that are oriented towards the carbons, the s-amount is $\frac{1}{1+5} = \frac{1}{6}$
  Addition of all s-amounts at a single carbon with all four bond orbitals yield: $\frac{1}{3}+\frac{1}{3}+\frac{1}{6}+\frac{1}{6}=1$, which is correct, because there is only one single s-orbital at every carbon atom.

  For p:

  In the orbitals that are oriented towards the protons, the p-amount is $\frac{2}{1+2} = \frac{2}{3}$
  In the orbitals that are oriented towards the carbons, the p-amount is $\frac{5}{1+5}=\frac{5}{6}$
  Addition of all p-amounts at a single carbon with four bond orbitals yield: $\frac{2}{3}+\frac{2}{3}+\frac{5}{6}+\frac{5}{6}$, which is correct, because there are 3 p-orbitals at every carbon atom.

  This means, that the bent bonds with $21^\circ$ from the $\ce{C-C}$-bond are spanned by sp$^5$ orbitals.

So math-magically this seems to make sense, but is there another explanation that might base more on chemical intuition or "real" chemical concepts?

A fast calculation ($\omega$B97X-D/def2-TZVPP) and a subsequent analysis of the isosurface of the Laplacian of the electron density, showed at least the expected "nonlinear", slightly curved bond between the carbon atoms.

Whoever might want to see the electron localization function (ELF), which also shows the bent bonds quite good:

$^\ast$ While I tried to translate it to my best, some errors might have been introduced by this . . . please correct me, where I'm wrong.


texts: Changing the suffix of the name of a compound loses one hydrogen atom?

texts:
I just chanced upon these intriguing pubchem entries: Ethyl Carbylamine and Ethyl Isocyanide. Their structures - as given on that site - are respectively:

 and .

Notice that the only difference is the H atom on ethyl carbylamine, which is missing in ethyl isocyanide!

I always understood carbylamine and isocyanide being interchangeable suffixes for an IUPAC name, but it seems like I've been proved wrong.

  What is the reason for such an anomaly in the structures of these two compounds?


texts: How to interpret the instruction of the dilution of hydrogen peroxide?

texts:
I am required to prepare $\pu{120cm3}$ of hydrogen peroxide to each of one of my students tomorrow. Some material is given to me on the method of preparing the solutions. Within the method of preparing $\ce{H2O2}$, it says:

  Prepare from freshly purchased $100$ volume ($30\%~\text{w/w}$, $\pu{8.3 mol/dm3}$) or $20$ volume ($6\%~\text{w/w}$, $\pu{1.7 mol/dm3}$) $\ce{H2O2}$. Dilute $\pu{200 cm3}$ of $100$ volume solution to $\pu{1 dm3}$ of $20$ volume solution, then dilute $\pu{59 cm3}$ of $20$ volume solution to $\pu{1 dm3}$ of $\pu{0.1 mol/dm3}$ solution.

Can someone please explain the quoted part?


texts: How were x-ray diffraction patterns deciphered before computers?

texts: I know the general idea behind x-ray crystallography is to take a high quality crystal and place it in the path of an x-ray beam. Areas of high electron density will diffract the beam and lead to spots on a detector screen where photons have constructively interfered with each other (and nothing appears where destructive interference has occurred). The crystal is then rotated and another diffraction pattern image is taken and the cycle repeats until there are enough views to reconstruct the atomic structure of whatever you crystallized. My question is what is the general process for doing this without computer software? How was this done in the 20s? The only equation I know for x-ray diffraction is Bragg's Law but is this the only equation used to interpret the data? Surely there must be others? How do you translate the spots on a detector to electron density plots using Bragg's law?


texts:
I'm a Mechanical Engineering student and I have been working on a school project but I want to go a bit beyond that and it has led me here. I'm designing an engine cylinder, and I figured I should be able to calculate the heat of combustion of the working fluid.

Please remember that I have no chemistry textbook and all I have been doing up to now is using the internet and some vague memory from high school.

So I wrote the balanced equation,

$$\ce{C8H18 + 12.5\left(O2 + 3.76 N2\right) -> 8 CO2 + 9 H2O + 23.5 N2}$$

using that I was able to compute the air-to-fuel ratio, individual masses for the $1.8\ \mathrm L$ volume, etc. I settled on a compression ratio of 8 which after some thermodynamic computation (if neccessary I'll present them) I got to the following state,

$$
T_2 = 650.9 \; \text{K} \\
P_2 = 1779 \; \text{kPa}
$$

basically those are the conditions prior to the spark. I'm trying to compute the heat of combustion using those properties. Using Mathematica I found out that for Octane the heat of combustion is somewhere along,

$$
\Delta H=5474\;\frac{\text{kJ}}{\text{mol}}
$$

but I assume this is for STP, my interest is to calculate for my conditions at state 2. After some bit of research I noticed one has to use the specific heats of the participants, but the website stated 'find these at the end of the book' – which I don't have one. To be honest, it will probably take me days to figure out this problem on my own using the internet. So does anyone know of a shortcut such as an online database or some public tables that display specific heats (maybe as a function of temp) for octane. Or how would you go about solving my problem?

Remember that I don't have much knowledge regarding advanced chemistry, and most of my interest lies in the field of engineering.


texts: How does an anode metal come into solution if it cannot react with an electrolyte?

texts:
From what I understand, an anode material is chosen so that it does not react with the anode electrolyte solution.

I was just wondering, then, that when you have a galvanic cell which has a Mg metal anode submerged in sodium chloride solution, how the magnesium metal gives two of its electrons and come into solution (as magnesium ion) even though it does not react with (and cannot react with) sodium chloride?

What I mean is, in a typical single displacement reaction, there is a metal that reacts with the solution and comes into solution. For example, with $\ce{Zn}$ and copper sulfate, the zinc replaces the copper and comes into solution as zinc ion. However, magnesium doesn't react with sodium chloride (because the activity series predicts it can't). How then can we say that we have magnesium ion in solution?

Is it that the metal is more stable in its ion state and thus readily gives up its electrons?

Traditionally, the anion is the one responsible for giving electrons: the chloride ion in the sodium chloride solution should come into contact with magnesium anode and give its electrons, which the magnesium metal should then carry. And thus the reaction should be

$$
\ce{ 2Cl- \!(aq) -> Cl2\!(g) + 2e-}
$$

and not

$$
\ce{Mg\!(s) -> Mg^2+\!(aq) + 2 e-}
$$

However, my books don't say this: they say that magnesium gives up two of its electrons and enters the solution.

What am I understanding wrong?


texts: Oxide caused by running a saucepan with aluminium handle through the dishwasher

texts:
Having run a saucepan with an aluminium handle through the dishwasher, the handle is producing a dark grey dusty residue, which I assume is an oxide of aluminium. The dishwasher was run with a typical dishwashing detergent as well as some drying agent (potentially).

The residue can be scoured off, leaving the shiny aluminium below. Having been scoured, the oxide doesn't seem to return.

What reaction is responsible for this? Obviously the high temperatures of the dishwasher is one factor, but what are the others?


texts: Why is the boiling point of sulfuric acid much higher than that of phosphoric acid?

texts:
Why is boiling point of sulfuric acid much higher than that of phosphoric acid?

According to the data book,

• The boiling point of sulfuric acid is 337 °C (639 °F; 610
   K) When sulfuric acid is above 300 °C (572 °F), it will decompose
   slowly.

• The boiling point of phosphoric acid is 158 °C (316 °F; 431 K) When phosphoric acid is above 213 °C (415 °F; 486 K), it will decompose slowly.

However, sulfuric acid can only form 2 hydrogen bonds per molecule but phosphoric acid can form 3 hydrogen bonds per molecule. While both of them are strong acids which can undergoes complete ionization, what other factors that I've ignored may lead to the fact that boiling point of sulfuric acid is much higher than that of phosphoric acid?


texts: Comparing acid strength of oxoacids derived from oxides

texts:
Acidic strength has been compared before here and here, but the first question is about organic chemistry (and I am talking about inorganic chemistry), and the second does not discuss molecules such as $\ce{Cl2O7}$, $\ce{P4O10}$, $\ce{CO2}$, $\ce{N2O5}$, $\ce{Al2O3}$ etc. These molecules do not contain hydrogen. So what are the factors which affect their acid or base strength?
The following question brings me this doubt:

Which of the following is the correct order of acidic strength?
(A) $\ce{Cl2O7}$ > $\ce{SO2}$ > $\ce{P4O10}$
(B) $\ce{CO2}$ > $\ce{N2O5}$ > $\ce{SO3}$
(C) $\ce{Na2O}$ > $\ce{MgO}$ > $\ce{Al2O3}$
(D) $\ce{K2O}$ > $\ce{CaO}$ > $\ce{MgO}$


texts: why is NaOH used instead of KOH for preparation of K2Cr2O7?

texts: I have been told by my teacher that we use NaOH for the first step of preparation of potassium dichromate to form sodium chromate, which then reacts with conc H2SO4 to form sodium dichromate. Then it undergoes a double displacement reaction with KCl to form K2Cr2O7..My question is that why cant we directly use KOH in the first step so that we dont have to use the third step?


texts: I wonder if alkyl halides react with alcohols or not. I searched on Google but could only find reaction of alcohols with hydrogen halides


texts: Chemical formula of ethanol and other carbon compounds

texts: Should chemical formula of ethanol be written as $\ce{CH3CH2OH}$ or $\ce{C2H5OH}$? And whats the logic behind it? I have seen the former being used more often, so why is ethane represented by $\ce{C2H6}$ than $\ce{CH3CH3}$?


texts: What is the product after treating ethene successively with chlorine and water, sulfuric acid, and potassium hydroxide?

texts:
Question:

  Ethene reacts with $\ce{Cl2}$ in $\ce{H2O}$ to form A. A on reaction with $\ce{H2SO4}$ followed by heating gives B. B on reaction with alcoholic $\ce{KOH}$ gives C. Find C.

My answer is:

A: $\ce{CH2(OH)CH2Cl}$
B: $\ce{CH2=CHCl}$
C: ethyne.

Explanation:

Ethene on reaction with chlorine water undergoes addition reaction to give A. A on reaction with $\ce{H2SO4}$ followed by heating undergoes dehydration to give B. B on reaction with alcoholic $\ce{KOH}$, undergoes elimination to give ethyne.

But the answer given is $\ce{CH2=CH-O-CH=CH2}$.

Where I am going wrong and what are the products?


texts: Is this the right conclusion for a thought experiment?

texts:
In this thought experiment, let’s consider the surrounding to be air that is composed of entirely water vapor (no other species like $\ce{O2}$ and $\ce{N2}$ are present). The surrounding is infinitely large. The system in question is a pan containing a thin layer of liquid water. The liquid water is brought to its boiling point by uniform heating. This pan is open (not covered in any way) and is exposed to the surrounding water vapor.

By definition, boiling occurs when the vapor pressure of the liquid is equal to the external pressure. So in this case, at boiling point, the vapor pressure of the liquid $\ce{H2O}$ is equal to the external pressure of gaseous $\ce{H2O}$. Thus, the system is in a dynamic equilibrium, and the rate of vaporization is equal to the rate of condensation.

This implies that the amount of liquid water will not change over time. In particular, it will not all “boil off” as steam. Is this the right conclusion? It certainly seems a little absurd.


texts: How do you calculate the delta H for multiple reactions?

texts:
I am having difficulty in a question:

Given that
1. $\ce{N_2(g) \rightarrow 2N(g), \Delta H = 941 kJ/mol}$
2. $\ce{N_2(g) \rightarrow N_2^+ + e^-, \Delta H = 1501 kJ/mol}$
3. $\ce{N(g) \rightarrow N^+ + e^-, \Delta H = 1402 kJ/mol}$,
Find the energy interval that produces atomic nitrogen in the flask but not any ions

I think that the energy interval should be $ 941 \leq E \leq 941 + 1402$, but the textbook says that the energy interval should be $ 941 \leq E \leq 1402$.
I think I am correct because $\ce{1402 kJ/mol}$ is needed to be supplied after the initial $\ce{941 kJ/mol}$ that is used to break the $\ce{N_2}$ bond.
Can someone please see the flaw in my reasoning?


texts:
The physics part: The part that talks about being shiny, I agree, is mainly physics. But proceed in my question, and you'll see how it's a chemistry one.

We know things are shiny if they either produce light, or deflect light well. Producing is not our topic in here, but deflecting is. Metals are considered shiny objects.

Mad scientist (the site, not our fellow friend!) has provided a nice explanation for why metals are shiny: In short, because free electrons (electrons are partially "free" in metals, due to the especial way of bonding) deflect more photons than usual and do not let the inner layers of atoms in the metal absorb them.!

(These three differ in shine because of impurity; not related)

Metals aren't the only materials that are exceptionally "shiny". We are aware of many crystals that are either well-cut or well-formed, which result in total internal refraction and that makes them very shiny too. There's a related question in physics.SE wherein the diamond's shiny properties are questioned.

The organic-chemistry part:

Saying the word "oil" talks about a vast variety of chemicals; therefore, in an attempt to narrow down the question, I only ask about liquid-at-RTP triacylglycerol (the famous triglycerides which exist usually in plants or fish). The chemical structure is as following:

My question is: Organic molecules like these aren't metals, are they?! So since a thorough research (maybe seemingly) didn't get me answers about why these are good light reflectors I'm asking for a way that will allow me to compare the reflectivity of these liquids, primarily from their structural formula. e.g.: Are these liquids "shinier" than water? Why? About water, I would say that for example, Hydrogen atoms in correspondence to the Oxygen atom, make water have hydrogen bonding, which is the main cause of surface tension. Surface tension causes the surface of water to be "smoother" and thus the reflectivity increases. On the other hand, it can't be only about Hydrogen bonding, can it?

(If the answer might be too broad, you may guide me to any resource helping me to find an answer, and that's why I add the tag: reference-request.)

Image sources: http://www.luxrender.net/wiki/images/2/2f/Shiny_yellow_specular_series.jpg ; http://library.med.utah.edu/NetBiochem/FattyAcids/7_2.html ; http://guweb2.gonzaga.edu/faculty/cronk/biochem/images/triglyceride.gif


texts: Two different answers obtained by balancing this chemical equation!! Somehow

texts:
This is the concerned equation:

$\ce{ XeF4 +  H2O ->  Xe + XeO3 + HF + O2}$

This can be balanced as

$\ce{6 XeF4 + 12 H2O -> 4 Xe + 2 XeO3 + 24HF + 3 O2}$

or

$\ce{5 XeF4 + 10H2O ->3 Xe + 2 XeO3 + 20 HF + 2 O2}$

Former is what found in this book.  NCERT chemistry part one, the textbook for class 12th. Chapter 7 page number 205 (b) Xenon Oxygen compounds, at the top.

while the latter is the one I come up while I was messing the equation. Something is wrong here. But what?


texts:
What is meant by a an ideal chemical system?
Moreover, is it true that only in an ideal chemical system the equation

$$\mathrm{d}U = \mathrm{d}H - \mathrm{d}(pV),$$

i.e.

$$\Delta U = \Delta H - \Delta (pV)$$

can be written as

$$\Delta U = ΔH - pΔV?$$

If so, why?

I also presume that non-ideal chemical systems do not maintain a mechanical equilibrium. If I am wrong, please correct me.


texts:
A Millimeter of Mercury(mmHg) is by definition the pressure exerted on a column of mercury 1 mm  in height.

I found this definition confusing because it doesn't say how the diameter of the container will affect the pressure.


texts:
I'm in general chemistry, and I was wondering how ionic species crystallize and form the shapes they do, specifically in regard to the Struvite precipitate $\ce{MgNH_4PO_4. 6H_2O}$.
Deconstructing the ionic species, we get $\ce{NH_4^+}$, which does not have a dipole moment (I think), $\ce{PO_4^{3-}}$, which also does not have a dipole moment, $\ce{H_2O}$, which has its dipole moment pointing towards the oxygen, and $\ce{Mg^{2+}}$, which is just an ion floating in solution.
Drawing the lewis structures of these molecules and writing the lewis structures, I'm not really sure how the crystal would form. But I do have a guess.
I feel as if the $+1$ formal charge on the nitrogen in $\ce{NH_4^+}$ will be attracted to one of the $-1$ formal charges on the oxygens in $\ce{PO_4^{3-}}$, while the magnesium ion will take in some of the free electrons on the other two oxygens. The $\ce{H_2O}$ will then form hydrogen bonds with the net dipole moment generated?
But this all sounds so hand-wavy to me, and I know it's probably wrong. Furthermore, I can't really visualize what this would look like. I honestly don't have a good understanding of how things work with crystallization. This is, after all, my first semester of chemistry.
If someone could give me tips and hints on how a struvite unit arranges its ions via electrostatic interactions to make something stable, I would appreciate it. Resources and pages in textbooks would be appreciated too!


texts: How to do pre-treatment on surface and how to clean the glass surface after silanization?

texts:
By Silanization, I want to treat surface of some spherical glass beads. Each bead is supposed to be shot in a particle launcher (like a bullet from a gun). I have some detailed question for the process:

1) Do you think that the hydrophobic coating which is created on the glass bead surface is durable enough that not to be removed or scratched by friction due to SOFT rubbing to the particle launcher tube?

2) Before silanization, should I perform any pre-treatment on glass surface? (e.g. pouting the glass in acid, or heating the glass surface, etc ...)

3) After I take out the glass from pool of silan, the glass surface is partially covered with reactant agents which is hardly cleaned with water. How should I clean the silanized surface after taking out from the pool? (using acetone and rubbing with a napkin is okay, etc)


texts: Can anyone identify this uncaptioned diagram?

texts:
It's from the start of part 3 / chapter 19 in Lewin's Genes X (see this page in Google Books)...

Looks a bit like a Ramachandran plot(?) but the axes only go to 100 / 70ish, but I don't even know what molecule it is since it doesn't say and there's no image attribution page at the front/back.

Any sleuths out there?


texts: Question regarding chemical equilibrium when adding a salt to acid solution

texts:
Having read the following was wondering something:
$$\mathrm {p}K_\mathrm{a} = -\log\frac{[\ce{H+}]_\mathrm{eq}[\ce{A-}]_\mathrm{eq}}{[\ce{HA}]_\mathrm{eq}} $$
$$\ce{HA <=> H+ + A-}$$
$$\mathrm{pH = p}K\mathrm{_{a}} +\mathrm{log\frac{[\ce{A-}]}{[\ce{HA}]}} $$
This rmgd
$$ \mathrm{[\ce{A-}] = [salt] }$$
when acid is weak.
Now my question is like this: take a beaker of $\ce{CH3COOH}$. Now add $\ce{CH3COONa}$. Now here using the a over formula as salt concentration increases $\mathrm{pH}$ should decrease when take in $\ce{A-}$ as salt concentration. However this same $\ce{A-}$ was there in the $\mathrm{p}K_\mathrm{a}$ formula so shouldn't the $\mathrm{p}K_\mathrm{a}$ change to compensate? If so then there will be no $\mathrm{pH}$ change but I have read that there is $\mathrm{pH}$ change on adding $\ce{CH3COONa}$ in a solution. What is wrong with this?


texts: What is the explanation of negative temperature coefficient in ignition delay of a fuel?

texts:
When studying the ignition delay of a fuel, some fuel have a negative temperature coefficient area (NTC) where an increase of initial temperature of the mixture air/fuel produces an increase of the ignition delay:

What is the explanation of the NTC phenomena? Why does the ignition delay increases when initial temperature increases only for a limited range of temperature? What is happening inside the mixture air/fuel that explains NTC?


texts: How much CO2 is emitted by burning coal to produce 1 kWh of energy

texts:
I'm a little embarrassed to ask this question at this stage of the climate game but, in searching, I seem to get contradictory answers.

For example, here: https://www.eia.gov/tools/faqs/faq.php?id=73&t=11
we see 215.4 lbs CO2 giving 1 million btu heat. Since 1 million btu = 293 kWh, we end up with 0.735 lbs/kWh.

But at this site: http://shrinkthatfootprint.com/electricity-emissions-around-the-world
we see 1 kg/kWh = 2.2 lbs/kWh

New York times https://www.nytimes.com/2007/11/07/business/businessspecial3/07carbon.html
gives 1.9 lbs/kWh

These are very different numbers (too different for the problem to be type of coal, at least for eia vs NYT) and I have found other numbers at other sites.

Can anyone point me to a site that I can trust for this number and others like it (related to energy production)?
Or else point out the elementary error I am making?


texts: Is the Kekule structure of benzene completely wrong?

texts:
I've found out about something called resonance but I'm getting the impression that this indicates the kekule structure is possibly correct as it uses double bonds (I thought that the delocalised model was the only correct one).

I'm a little confused on this so could someone clarify?


texts:
In an attempt to clean drain cleaner, I reacted it with Sodium percarbonate to clean up some hardware store variety sulphuric acid.

At first the reaction appeared successful, yielding a Nice Clear Syrupy sulfuric acid with a heavy crystallization at the bottom of the flask, but I don't think the salt that I collected is sodium sulfate.

The crystals are very long resembling fiberglass and based on images I've seen online, sodium sulfate's structure seems to be a lot like sodium chloride.

I'm not sure of the conjugate base formed during the reaction ($\ce{SO4-, SO5- or HSO4-}$) can anyone explain?

EDIT

I've since learned that when basic sodium is reacted with $\ce{H2SO4}$ in a ratio favoring $\ce{H2SO4}$, the conjugate base produced is $\ce{HSO4-}$


texts:
Below is the structure of chloroazodin:

Why is chloroazodin poorly soluble in water? It has multiple amine and imine nitrogens, all of which appear to be available for hydrogen bonding, and thus it seems it should exhibit high aqueous solubility.

Chloroazodin is mostly insoluble in water and organic solvents. I can't explain this character which is in contrast with its structure.


texts: What would happen to a Water/Lard Mix under pressure and high heat?

texts:
If water is mixed with lard oil and heated (creating some super-critical water), how does this affect the volatility of the mixture in comparison if it is a pure mix of either water, or lard oil?

What happens when a mixture of lard oil and water is compressed and then heated to over 800 degrees Fahrenheit almost instantaneously (up to 1200 degrees Fahrenheit)? If it is in a well sealed copper container, would it be volatile enough to burst through the container?

Note: I'm no scientist or chemist, so use of laymen's terms, if possible, would be appreciated


texts: Active transport of Ca2+ ions against chemical and electrostatic gradients, assisted by ATP hydrolisis

texts:
I have a homework question that I am not able to solve. No solution is available, so I was hoping someone here could help. The question is this:

  Calculate the maximal concentration ratio that can be obtained for
  transport of Ca$^{2+}$ ions if two ions are transported per ATP hydrolyzed
  at 310 K, and they are transported to a potential that is 70 mV higher
  at the receiving side. Assume that the $\Delta G$ for hydrolysis of ATP = -45 > kJ\mol.

Relevant formulas:

\begin{align}
\Delta G_{\text{electrostatic gradient}} &= ZF\Delta \Psi\\
\Delta G_{\text{chemical gradient}} &= RT\ln\frac{C_\mathrm{in}}{C_\mathrm{out}}\\
\Delta G_{\text{hydrolysis of ATP}} &= -45000~\mathrm{J/mol}\\
\end{align}

Moving two positive $\ce{Ca^2+}$ ions against both a concentration gradient and an electrostatic gradient implies that $G_{\text{chemical gradient}}$ and $\Delta G_{\text{electrostatic gradient}} > 1$. The negative value for $\Delta G_{\text{hydrolysis of ATP}}$ means that hydrolysis of ATP is a spontaneous process, or a "work-yielding" process. The energy released from hydrolysing ATP is essentially what drives the transport process. Since we are transporting "4 charges" per ATP molecule, $\Delta G_{\text{chemical gradient}}$ is multiplied by 2. Also (I presume) the concentration of $\ce{Ca^2+}$ ions is larger on the inside of the cell than on the outside, implying that the concentration ratio is larger than 1.

The combined expression for $\Delta G$ for the unassisted transport is

$$\Delta G = RT\ln\frac{C_\mathrm{in}}{C_\mathrm{out}} + 2ZF\Delta \Psi$$

Rearranging this yields

$$\frac{C_\mathrm{in}}{C_\mathrm{out}} = \exp\left\{\frac{\Delta G - 2ZF\Delta\Psi}{RT}\right\}$$

I am not sure what to plug in for $\Delta G$, but it needs to account for the push from ATP. I believe this is done by summing the two free energies affecting the transport, ergo the sum of $\Delta G_{\text{electrostatic gradient}}$ and $\Delta G_{\text{hydrolysis of ATP}}$. However, this gives me a concentration ratio much smaller than 1.

Can anyone see where I am incorrect?


texts:
A gas adiabatically expanded from $\pu{32atm}$ and $\pu{273K}$ to $\pu{1atm}$ and $\pu{251K}$, Calculate Joule-Thomson coefficient $\mu$ at $\pu{273K}$.

Answer:

$$\mu = {\Delta T \over \Delta p} = {-22 \over -31} = 0.7$$

I think the answer uses the definition of $\mu$ that is $\displaystyle\left({\partial T \over \partial p}\right)_H$, but this definition assumes the process to have constant enthalpy.

But in adiabatic process $dH = dU + Vdp + w_{ad}$, so for $dH = 0$ we need to have $dU + Vdp + w_{ad} = 0$ which is not possible since pressure is clearly changing and so $Vdp$ is not zero.

My questions are

Is $dH = 0$ for a adiabatic and I am missing something ?
If not then how did the author used $\displaystyle\left({\partial T \over \partial p}\right)_H$ to get the answer ?


texts: Why does tea dissolve better when put in water rather than milk?

texts:
I sometimes drink tea with or without milk. What I have noticed is that when I dip the bag in water the tea spreads out evenly and I have a cup of tea in like 5 minutes.

But when I do the same with milk in it, the tea takes forever to dissolve into the milk and even after a long time half of the milk is absorbed by the tea bag for some reason.

Could someone explain me why this is happening?


texts: Recommendations for textbooks with correct and up-to-date information

texts:
I recently began studying chemistry, only to find out that, apparently, concepts such as “octet expansion” and Lewis structures are outdated and incorrect. And I don’t mean they’re approximations of reality, as is the case for numerous theories taught in physics, but, apparently, actually incorrect and deprecated concepts. However, commonly promoted textbooks still teach these concepts as though they are true, with no reference to them being outdated or incorrect. I find this both disappointing and disturbing, since I want to learn concepts that are actually correct. And when I purchase (expensive, recently published) textbooks, I expect to be taught correct and up-to-date concepts — especially since the people who wrote these textbooks are in an academic position to know better.

At the moment, my goal is to study both physical and organic chemistry. I was wondering if people could please recommend good textbooks in these areas that do not teach incorrect, outdated, and deprecated concepts.


texts: What is an effective fabric-friendly solvent for aluminium chlorohydrate?

texts:
I have recently found out that the white/yellowish "sweat" stains one  occasionally finds on t-shirts might be aluminium chlorohydrate polymers.

While talk about aluminium and antiperspirants is all over the press and there are lots of DYI-instructions for removing them, they all sound quite pseudoscientific.  I find it strange, for instance, that some guides recommend both vinegar and/or baking soda as a remedy...

Any ideas what else I could use to dissolve such stains without also dissolving much of the pigments?


texts: How long does it take to turn aluminum smelters on and off?

texts:
This may fit better under "engineering," but I figured I'd start here.

Aluminum is produced through an electrolysis process, and Wikipedia tells me that the electrolytic cells need constant power in order to operate - that if the aluminum solidifies, you can't just turn the thing back on.

I'm curious as to how long it takes to turn these processes on and off at a commercial aluminum smelting operation. Is it the sort of thing you can start in the morning and turn off in the evening when the plant closes, or do you really want to operate the cells 24-7?


texts: How mass spec formate and acetate adducts masses are calculated?

texts:
If I look at any tables or calculators, I find that negative ion formate adduct has a monoisotopic mass of +44.9982 units. If I try to calculate myself, I get slightly different result:

H + C + O + O =
1.007825 + 12.0107 + 15.9994 + 15.9994 =
45.017325

The difference is 0.019, what is already not indifferent, as usually I calculate with a tolerance of +- 0.02 units, which means this can cause me miss many hits. I could not find out what may cause this difference.

Later had similar experiences with the acetate, as in tables +59.013851 can be found, but if I calculate:

3 x H + 2 x C + 2 X O =
3 x 1.007825 + 2 x 12.0107 + 2 x 15.9994 =
59.043748

Which means even more, 0.0298 difference.

My question is what causes the difference, and what is the correct wat to calculate these masses?


texts: Where did the rest of the elements come from?

texts: There were ninety original elements on the Periodic Table. Over time, new ones were founded and put on. However, they were all either the original elements experimented on. For example, Plutonium was discovered by deuteron bombardment of uranium. Therefore, I would like to know: How were the rest of the elements discovered? It would also be nice if an example could be given. Thanks!


texts: Why is the melting point of TiCl4 lower than TiCl3

texts:
I was wondering why the melting point of $\ce{TiCl4}$ was below that of $\ce{TiCl3}$

The melting point of the former is  $\ce{-25 Celsius}$ whereas the latter is $\ce{425 Celsius}$ .

Thanks!


texts: Are all lift-off resist negative photoresists? I'm a bit confused as I can't find anything in my textbook/lecture slides about the type of resist used for lift-off.


texts: Why isn't ionization energy called cationization energy?

texts: I'm learning chemistry and ionization energy is "[...] the amount of energy required to remove the most loosely bound electron, the valence electron, of an isolated gaseous atom to form a cation." It seems more intuitive to me to call this cationization energy. Other than historical reasons and convention, are there any reasons why it's not?


texts:
How to describe the enthalpy of acid dissociation in aqueous solutions?
If we had a weak acid "PB" that dissociates to give a proton and a conjugate base. Classically it would be described like the following:

Unfortunately, things aren't that simple in aqueous solutions. Each of the dissociated molecules will have a charge which will change its polarity and water hydration (solvation).

a better way would be to describe dissociation in gas phase then the solvation of each:

Is this description accurate? Is the enthalpy of protonation measured by calorimetry or calculated by the Van't Hoff analysis the "dissociation" or the "Ionization"?


texts: Raoult's law & Dalton's law of partial pressures

texts:
I am confused between Raoult's law and Dalton's law of partial pressure as they state completely different things about same thing...

Raoult's law claims $p = P \cdot x$
where $p$ is the partial pressure of a gas, $P$ is the pressure of the same gas at the same temperature and volume and $x$ is the mole fraction.

Dalton's law says $p = p_\text{total} \cdot x$
where $p_\text{total}$ is the total pressure of the mixture.


texts: In acid/base chemistry, are there amphoteric substances that undergo something that resembles disproportionation in redox chemistry

texts:
Some substances disproportionate. This means a species with an intermediate oxidation state yields two species with higher and lower oxidation state. For example:

$$\ce{Hg2Cl2 -> Hg + HgCl2}$$

My question is if there are substance that have the analogous acid/base behavior, where an intermediate protonation state yields the conjugate acid and the conjugate base. You could write it like this:

$$\ce{2AH -> A- + AH2+}\tag{1}$$

An example would be water:
$$\ce{2H2O <- OH- + H3O+}$$

What I am looking for, however, is a case where the mixture of conjugate acid and the conjugate base (of the same amphoteric starting material) are the major species, i.e. a reaction of the type (1) with an equilibrium constant larger than 1. This would mean that the pKa values are in the opposite order than usual, i.e. it is "easier" to lose the second proton than it is to lose the first. For disproportionation, there is a similar feature of the reduction potentials (it is easier to accept the second electron than it is to accept the first).

Are there any such examples?

Update: To clarify my question, I am looking for substances that skip a protonation state, i.e. pKa2 < pKa1. If you could isolate the intermediate protonation state, it would yield the higher and lower protonation state. This is similar to species that skip an oxidation number (or have the corresponding species at very low concentration) because the reduction potentials favor disproportion of the (hypothetical or barely detectable) species with intermediate oxidation state.


texts: Is it practical to extract zymase from yeast for ethanol production?

texts:
Suppose I wanted to make some ethanol fuel. Normally, I would get yeast, mix with water, add sugar and wait. However, there is an enzyme (zymase) in yeast that does this. Looking at the Wikipedia article for zymase, someone managed to extract it using only quartz and diatomaceous earth.

The advantages of this is that it could potentially produce large amounts of concentrated ethanol, whereas yeast could only produce less than 20% due to it dying. So, do people use such a method, and if not, why not?


texts: what happens to hydrogen released in addition polymerization?

texts: In formation of polyethylene(free radical method), the free radicals when attached to another ethene molecule release a hydrogen(I think).But addition polymerization does not release and by product, so what happens to that hydrogen atoms?


texts: Calorimetry: Temperature Increase due to stirring of reactants

texts:
I am not yet in university, but I hear a common first-year chemistry lab/practical is to do calorimetry taking into consideration the small (and usually negligible) rise in temperature due to the reaction container being stirred.

What is the standard method for estimating/calculating this increase in temperature, given the rate at which the stirring occurs and all the other necessary information? Is this possible to obtain an answer using molecular kinetics or are these calculations done solely on guesswork?


texts: 2 electrons with the same spin in the same orbital

texts: When two electrons are in the same orbital and they have the same spin do we say that the electronic configuration is impossible or that it refers to an excited state?


texts:
Why is ethanoic acid more acidic than phthalimide? $\mathrm{p}K_\mathrm{a}$ of phthalimide is 8.3 (source), while that of ethanoic acid is 4.76 (source).

Applying the logic found here would suggest the opposite. This is because both conjugate bases delocalize their negative charge, but while ethanoic acid has two oxygens to delocalize its charge among, phthalimide has two oxygens and a nitrogen (and a benzene ring); it seems that the quality of the delocalization is the same, but the quantity favors phthalimide (as the answers to the question put it). As for the other factors that affect acidity (inductive effects, hybridization, atom size/electronegativity, formal charge, etc.) none seem to come into play.


texts: What happens when you mix Pine Sol with Clorox

texts:
I have read all these rumors online that mixing these two solutions will produce the chloride gas. I accidentally mixed these two while doing berthing cleaners in the communal restroom and felt very light headed afterwards.

Pine-sol contains glycolic acid (1.75%) and the other ingredients are C10-12 alcohol ethoxylates, dimethicone/silica/PEG distearates, sodium C14-17 secondary alkyl sulfonates.

My Clorox contains 8.75% sodium hypchlorite.

Are the culprits in producing chloride gas glycolic acid and sodium hypochlorite? I'm not too familiar with chemistry and I need someone who took college organic chemistry to explain this to me. I'm in the military so I can't take physical classes. I would also like to know the mechanism.


texts: Why do tosylation and mesylation of alcohols follow different mechanisms?

texts:
Why do the tosylation and mesylation of an alcohol proceed via different mechanisms?

More specifically,

In tosylation, the lone pair of the alcohol attacks the sulfur in TsCl, but why does it not do so with MsCl? Surely, TsCl should be more sterically hindered due to the benzene ring.
Why is the sulfene intermediate even formed in mesylation? Can that position be deprotonated by $\ce{Et3N}$? It's clear that this mechanism cannot happen with TsCl which has no alpha protons, but I fail to see why it should happen with MsCl.

Tosylation with pyridine:

Mesylation with triethylamine:


texts:
For example, how do the bonds in NaCl form?

I understand that the elements need to obtain an octet structure to become more stable, by either accepting or losing electrons.

In NaCl, from my understanding, the sodium atom loses an electron and gives it to the chlorine atom, in turn gaining a +1 charge and then causing chlorine to have a -1 charge.

The new compound formed is NaCl. How does it form ? Do i need to place the respective atoms close to each other? What is needed to them to bond? Also, what is needed for bonding for other types such as covalent and metalic? Does it happen naturally ?


texts: What will the products on addition reaction of 1,4-benzoquinone with HBr ?


texts: Why are oxides always of the form AyOx with A representing any atom except oxygen and fluorine

texts:
I notice that for quite a few elements, oxygen comes before it in alphabetical order. Here is one of the rules in inorganic chemistry for molecular formulas:

Put all the elements in alphabetical order.

So why do oxides always have what is being oxidized followed by oxygen?

That makes some molecular formulas like PO4 for phosphate violate the rule in inorganic chemistry that the elements are arranged in alphabetical order.

I guess all oxides have some element(except for oxygen or fluorine) followed by oxygen because:

1) it clarifies that what you are talking about is an oxide of that element.

and

2) the structure of an oxide is always some element with oxygen atoms around it.


texts:
I'm working on upgrading my current skin adhesive emulsion. It is a roll-on skin adhesive used to keep clothing attached to the skin. Ingredients are; Alcohol Denae,Ethyl Ester of PM/MA Copolymer,Water, Butylene Glycol, and Aminomethyl Proponal.

What ingredient(s) could be used to:

Improve formula so that it is more pliable(as far as the skin moving with fabric).
Still maintain a strong bond/hold(possibly even stronger then current formula).
Have the overall formula be slightly less wet/runny (as it sometimes absorbs through clothing).
And when the formula sets, remains fairly matte/dry to the touch.


texts: Does bleach react with disinfectants containing quaternary ammonium salts?

texts:
My mom went nuts when we pulled up the laminate to discover mold growing on the subfloor. She sprayed bleach all over it while I was at the store buying Mold Armor mold remover and disinfectant, and found out from calling poison control that this product should not be mixed with bleach. The operator was not sure what I could do to make it so it was safe to apply the mold remover.

Can anyone tell me if when bleach dries, the chemical reaction will be mitigated? I just want to clean my house without killing everyone. The surface is porous, and made of wood/particle board.


texts:
I posed this question at the Seasoned Advice SE and thought I might get some more information here.

Traditionally prepared corn is cooked in a calcium hydroxide solution to make it more digestible, but when my search for $\ce{Ca(OH)2}$ hit a dead end, I began thinking: could I make a substitute with stuff I already have (sodium hydroxide, which I use for pretzel/soap making; and calcium chloride, for brewing)?

My thought process was that, upon dissolving, sodium hydroxide plus calcium chloride would provide the same ions (though not necessarily in the same concentration) as calcium hydroxide and sodium chloride. Since I would be adding salt to this recipe at some point anyway, I didn't see any harm to this.

Is this feasible, or am I off-base in my chemical understanding about this? More importantly, is there some chemical consideration I've failed to take into account?


texts:
For a metal cup as opposed to a styrofoam cup calorimeter, do you expect the enthalpy of the reaction to be higher, lower, or the same?

I think the enthalpy of the reaction would be the same in the sytrofoam cup as the metal cup because enthalpy is a state function? So if the same products are yielded at the end along with the same reactants being used in the beginning, they'll have the same enthalpy because it doesn't matter HOW you got that enthalpy, just the final result? That's my reasoning but I'm not sure.

So does it matter that metal cup will conduct heat better because if they're using the same reactants it'll give you the same change as a styrofoam cup?


texts: How does dimethyltryptamine cross the blood-brain barrier?

texts: Is there a specific chemical reaction that enables dimethyltryptamine to cross the capillary edothelial cells?


texts: Why is condensation in dyed beverages colorless?

texts:
Does food coloring somehow evaporate and turn into nothing?   Or does the beverage itself being much more color intensive?

I had a bottle of Gatorade, colored Lemon-Lime (and flavored as such). I noticed that after leaving the bottle in the car during a hot day and returned to the car, that condensation had formed on the top parts of the bottle.

But the condensation is colorless; does this mean it is solely water that is evaporating from the drink itself as condensation occurs, leaving food coloring or the color of the beverage behind?


texts: Why anhydrous acetic acid is differentiating solvent?

texts: Anhydrous acetic acid is differentiating solvent in which strong acids show different strength but water isn't. Why anhydrous acetic acid shows the strength of acids clearly, but water solvent cannot do so?


texts: Why does ethane release more energy than ethyne when burned?

texts: My book explains that since ethane contains a single bond, ethene contains a double bond, and ethyne contains a triple bond, and that when burned ethane releases the most energy because "the fact that the lowest energy is released by ethyne is taken to indicate that this compounds bonds are already in the highest energy configuration. The high energy of  combustion for ethane on the other hand indicates that its bonds have lower energy to start with and can release more energy on combustion." This seems counter intuitive to me. Wouldn't the double and triple bonds release more energy because they're stronger and it takes more energy to break them? Any insight would be appreciated!


texts:
I want to run classical molecular dynamics simulations of a periodically replicated surface (rutile $\ce{TiO2}$ with grooves). In order to do so, I first need to solve for the partial charges residing on each atom of the surface. What electronic structure methods are available for determining the partial charges on a surface?

I am vaguely familiar with Mulliken population analysis, but my understanding is that this method is not the most accurate. What other methods are commonly used, and how accurate are each of these methods?

Finally, what are some good (and free) packages for performing such calculations? I've used SIESTA in the past, is that well-suited for determining partial charges of a surface?


texts:
How was it determined that the electron observed in the cathode ray experiments was the same particle that gave an atom its balancing negative charge?

Couldn't there have been an entirely different negatively charged particle? What justified that assumption?


texts: Why are bonding interactions so much stronger than interactions of other types?

texts: Why are bonding interactions so much stronger than all the other types of interactions like dipole-dipole, London dispersion, hydrogen bond etc. even though they are all of electromagnetic origin?


texts: Concentration of hypochlorous acid and hypochlorite

texts:
Given a total chlorine concentration  $c(\ce{Cl})_\text{tot}= \pu{0.1 M}$, with $\mathrm{pH}(\ce{Cl}) = 8$ and $\mathrm{p}K_\mathrm{a}(\ce{HOCl}) = 7.5$, how would you find the concentration of $\ce{OCl-}$ and $\ce{HOCl}$ disinfectants?

So far I think that I should start this way:

$K_\mathrm{a} (\ce{HOCl}) = 10^{-7.5}=3.16\cdot 10^{-8}$

I wrote up the reactions:

$$\ce{H2O + 2e- + OCl <=> Cl- + 2OH-}$$

Where $\ce{OCl-}$ is the conjugate acid and $\ce{OH-}$ the conjugate base.

$$\ce{HOCl<=> OCl- + H+}$$

The conjugated acid is $\ce{HOCl}$, the conjugated base $\ce{OCl-}$.

Now I use
$$\mathrm{pH}=\mathrm{p}K_\mathrm{a} + \log\left(\frac{[\text{conj base}]}{[\text{conj acid}]}\right)$$

and/or for weak acids
$$K_\mathrm{a}= [\text{products}]/[\text{reactants}]$$

But I'm not sure if this is correct and what values to use.


texts: Michael reaction or nucleophilic attack at the alpha carbon of an alpha-beta-unsaturated ketone?

texts: What conditions promote a nucleophile to undergo the Michael reaction over the nucleophilic attack at the alpha carbon of the carbonyl group in an alpha-beta-unsaturated ketone? I'm looking for an answer that considers organic and inorganic nucleophiles (like organocuprates/organolithium compounds).


texts: Inactive versus frozen orbitals in CASSCF

texts: Does it make any difference if I use the frozen keyword instead of the inactive keyword in MOLCAS CASSCF calculations?


texts: Can a stoichiometric mixture of oxygen and methane exist as a liquid at standard pressure and some (low) temperature?

texts:
This answer to the question Pre-mixing cryogenic fuels and using only one fuel tank written by a non-chemist (me) begins with:

At STP:

LOX's boiling point is 90.19 K
Methane's freezing point is  90.7 K

This does not a priori prove that a solution of the two can not exist. However it does mean that they can not be handled as liquids at the same temperature, making mixing the two more difficult.
We know that liquid air exists which shows that LOX and LN2 can mix together. But methane is an organic molecules and we know that heavier $\text{C}_n \text{H}_{2n+2}$ hydrocarbons include oils and waxes don't like to dissolve in non-organic solvents.

A stoichiometric mixture of oxygen and methane would be 2:1 molar:
$$\ce{ 2O2 + CH4 -> CO2 + 2H2O }$$
Though the two can not be conveniently maintained as liquids at the same temperature, can a stoichiometric mixture of the two exist as a liquid at some (low) temperature and standard pressure?


texts: Is it possible for a carbon atom with a negative formal charge to have ONE bond and ONE lone pair?

texts:
I was completing some problems from my textbook and found that the answer of this problem seemed incorrect to me.

From my limited understanding, carbon atoms with a negative formal charge must have 5 electrons (3 bonds and 1 lone pair), but this answer didn't match up with this rule.

I would really appreciate it if someone could tell me what I'm missing here.


texts: SMARTS string matching an aldehyde or a ketone where the target alpha carbon is less substituted than the other carbon

texts:
I need a SMARTS string that matches the following critereon:

It makes an aldehyde or a ketone only
The target carbon is an alpha carbon
The other alpha carbon must be more substituted (or be an aldehyde)
The target carbon must not be more substited than a secondary carbon

I came up with the following string:
[C;X4;$([H3,H2;$(CC(=O)[H])]),$([H3;$(CC(=O)C)]),$([H2;$(CC(=O)[C;!H3])])]

Translated, this is saying, the target carbon:

Has four bonds
Lives in any one of the following environments:

Is has two or three hydrogens and is on an aldehyde
Has three hydrogens and is on a ketone
Has two hydrogens and is on a ketone where the other alpha carbon does not have three hydrogens

But that seems very long for what seems like a simple critereon.
Any suggestions? Are there any cool SMARTS tips I'm missing?
Thanks,


texts: How to determine the conductivity of different chemical compounds?

texts: I am doing an experiment that involves testing the conductivity of three different chemical compounds dissolved in water. I will be testing Potassium Chloride, Calcium Chloride and Zinc Chloride. All three will be of equal concentration. Is there any way to determine the conductivity of different chemical compounds dissolved in water? Out of these three chemical compounds, which one will be the most conductive, and why? Is there any correlation between reactivity and conductivity of chemical compounds?


texts: Increase of peak intensity in case of hydrogen bonding

texts:
Typical motif in case of hydrogen bonds is charge transfer from electron rich acceptor Y to (usually) anti-bonding X-H σ* orbital. If so, the X-H bonding distance increases, bond weakens, stretching frequency decreases. In IR spectrum, it is visible as red shift of X-H peak and that particular peak intensifies.

Usually the peak intensity has to do with the amount of bonds it represents in the studied material.

Why does peak intensify in this case since it represents the same X-H bond, and the number of bonds is unchanged?
I would've guessed it would, on contrary, decrease, since proton exchange between X and Y may occur and sometimes X-H...Y would become X...H-Y.
What am I missunderstanding here?


texts: Does this particular molecule (pyridine-I-pyridine) have a common name?

texts:
Here's a pic of the molecule:

I've been investigating this system to test a computational chem method, but I've realized I don't really know a name for this system. $I-pyr_2$? $py_2I$?

In my mind I call it "pip" for pyridine-I-pyridine, but I don't want to publish and look silly finding out this has a common non-systematic name later (ex: quinine, caffeine, etc).

I'm not worried about getting an IUPAC name exactly right, becuase nobody actually does that. But if there's a more common way of calling it, that's what I want.


texts: What functional groups can 900-2500nm IR spectrometers detect?

texts:
3700 cm-1 corresponds to about 2,700 nm
650 cm-1 corresponds to about 15,000 nm.
Many cheap IR spectrometers ($7000 or so like the ones at Stellarnet) has range of 900nm to 2400nm (or 11,111 cm-1 to 4166 cm-1). In the following table or list of the molecules functional groups, the range is between 2700nm to 15,000 nm (3700 cm-1 and 650 cm-1). Outside of the range of cheap IR spectrometers. So what functional group or stuff can you see with IR spectrometers that has range below 2400nm (above 4000 cm-1)?
https://www.sigmaaldrich.com/technical-documents/articles/biology/ir-spectrum-table.html

see the link above for complete list


texts:
Sodium hypochlorite. $\ce{NaOCl}$.
Appears to be: one part sodium, one part chlorine, one part oxygen.
Five questions:

Couldn't it just as easily be 'liquid sodium' or 'liquid oxygen'?
It's not really any of these though, is it?
It's a compound of all 3, right?
So, doesn't the new molecule have it's own properties?
Or is a compound/molecule(s) properties simply derived from it's constituent elements?


texts: Why does (atmospheric) pressure have an effect on solubility?

texts:
The Wikipedia article titled Solubility table states that

  The table below provides information on the variation of solubility of different substances (mostly inorganic compounds) in water with temperature, at 1 atmosphere pressure.

Why does pressure have an effect of on solubility?


texts: Does computational chemistry get the molecular orbitals of dioxygen wrong?

texts:
The molecular orbitals of $\ce{O2}$ are typically shown as follows, with every orbital filled by a spin alpha (or up) and spin beta (or down) electron (except the homo levels which are singly occupied).

Calculations using for instance Hartree-Fock and density functional theory however produce alpha and beta orbitals with different energies - no degeneracy of alpha and beta orbitals. For instance, the B3LYP/6-311G** HOMO/LUMO levels (taken from the computational chemistry database) are as follows: alpha HOMO (-0.31186), alpha LUMO (0.19755), beta HOMO (-0.46536), beta LUMO (-0.11702). Clearly the HOMO levels are not degenerate, at odds with what we expect from the above molecular orbital diagram. Similar mismatch between the alpha and beta orbitals exists for orbitals below the HOMO, as well as using other levels of theory.

Is computational chemistry getting the orbitals of $\ce{O2}$ wrong? Am I missing something? Conceptually I can't grasp that alpha and beta orbitals have different energies since at least for the case of filled orbitals when the electrons pair up I expect them to have the same energy.


texts:
My professor noted that bromination with light and methylene chloride gives you exclusively the monobromination product.

However, bromination without light will give you the multi-brominated product.

I have no found any reference to bromination in my textbook nor online. Is the second statement an accurate statement?


texts: Are there well developed reaction mechanisms in inorganic chemistry like those in organic chemistry? If yes, please suggest an easy to follow reference.


texts: How to extract a image (vector graphic) from a surface EPS plot with GaussView?

texts:
I am quiet new to this field of chemistry. I work with GaussView and I created a surface plot for my molecule with the cube and surface generator. This works very well. Now I like to save and copy this image of my molecule with its surface. My favorite file type whould be a vector graphic type (eps or svg).
I don not know how. I tried the option with File -> Save Image. When I choose vector graphic as type I just get the structur of my molecule but not the surface (as well as a error message...). When I choose all the other file types I get nothing in the file just a black screen.
Where is my mistake? What do I constantly wrong? I see a lot of these plots in publications... I just want this plot for my PowerPoint...

I hope someone of you got a godd tip for me, thanks!


texts: Difference between the absolute thermodynamic scale and ITS-90

texts: What is the difference between the absolute thermodynamic temperature scale and the practical temperature scale: ITS-90?


texts: How does electrolytic conduction depends on the size of ions & their solvation?

texts:
The textbook says,

  The smaller the effective size of the ion after solvation, the greater will be its conducting power."

But, on the Internet, it is explained as follows:

  Radius decreases, smaller ions carrying current in small area, more associations with anions & due to this, the ions become heavy & they move with reduced speed as compared to less associated ones, & thus conductivity decreases.

The explanation is different to the what the book says.
Could someone please explain this?


texts: The way kinetics is taught at the undergraduate level (Arrhenius and collision theory) chemical equilibrium is determined governed immensely by activation energy of the reaction. According to thermodynamics, however equilibrium is a function of free energy change. In a way, thermodynamics and kinetics seem to contradict each other. What insight am I missing. Is the energy in energy vs reaction coordinates supposed to be Gibbs free energy instead of enthalpy? Would this imply activation energy changes as a reaction proceeds? Is the way kinetics is taught wrong?


texts: Half-Life of Radioactive Isotopes: Why? How?

texts: Why do radioactive isotopes have a half-life? I know that they decay in order to become stable but why would it take out enough subatomic particles to be half? Or am I approaching this question the wrong way: the remaining radioactive substance is going to be half in x amount of time and the other half will be stable atoms.


texts: What is the maximum homogeneous nucleation rate of supercooled liquid quartz?

texts:
I read in College Physics, Volume 1 (by John Oren Reed, Karl Eugen Guther) that fused quartz is just supercooled liquid quartz. Is it really supercooled liquid quartz?

As liquid quartz is cooled below its melting point, does it eventually get to a temperature where achieves such a high homogeneous nucleation rate that it can't be supercooled any further.

Is it the case that the homogeneous nucleation rate only goes up to a rate that's still low enough to avoid nucleation at the macroscopic level with slow cooling and then starts going down again as a result of bonds not getting broken and reformed as often due to the lower temperature?


texts: What is the net ionic equation for the reaction between Ba(OH)2 and H2SO4?

texts:
I know its either:

1.) Ba + SO4 = BaSO4

2.) Ba + 2OH + 2H + SO4 = BaSO4 + 2H2O

But can someone explain why water is or isn't part of the net ionic?


texts: Does anyone know a database that shows the effect of electrolyte concentration on the production of hydrogen gas during electrolysis of water?

texts: I'm currently studying in the International Baccalaureate model. This high school model asks their students to do an individual work called the Internal Assessment. One of the subjects I study is chemistry, and my Chemistry Internal Assessment is based on the production of hydrogen (a source of energy) in the water electrolysis as a way to save electrical energy. I was going to do an experiment to measure the production of hydrogen in the electrolysis of water with various concentrations of four different solutes (NaCl, NaOH, sulphuric acid and sodium bicarbonate, but any electrolyte will do). However, with the Covid-19 outbreak, I cannot go to the laboratory, so in order to get the data I need, I searched on google databases with the information I wanted, but I found barely nothing. These links (https://www.scirp.org/pdf/NR_2013032814044640.pdf) (https://pubs.rsc.org/en/content/articlehtml/2017/se/c7se00334j) are the only useful pdfs I found, and I wonder if anyone could help me giving me some databases with the data I need.


texts: Infinite Increase in Entropy when Energy added to Absolute Zero

texts:
My textbook states the following:

  If a system were at absolute zero, an additional small amount of heat energy would lead to an infinite increase in entropy. Such a state is impossible. Absolute zero can never be achieved.

It also provides the equation:

$$ \Delta S_\text{surroundings} = \frac{-\Delta H_\text{system}}{T}$$ Where $T$ is given in kelvin.

From the statement, will the entropy of the system or surroundings increase; from what I can deduce, I would say the entropy increase would be within the system as the surroundings is losing energy, but I am not sure.

The second part of my question is, why would this lead to an infinite increase in entropy? Please provide a comprehensible mathematical explanation and also, preferably, an analogy.

Textbook: Pearson Baccalaureate: Higher Level Chemistry, 2nd Edition. By Catrin Brown and Mike Ford Pages: 254-255


texts:
I have a lithium battery that is separated from any device and is producing a whitish-gray smoke every time the wires move. Sometimes it makes hissing noises.

Is there a way to solve these problems?


texts: Reactivity Towards Electrophilic Substitution

texts:
How do you decided which compound is the most or less reactive towards electrophilic substitution? For example, if the compounds are benzene, ethyl benzene, 2-phenylpropane and 2-methyl-2-phenylpropane?

Most reactive towards electrophilic substitution means that the compound itself needs to be an electrophile (so that they don't combine), this means there needs to be a +I effect, right? But +I effect increases with an increase in the number of alkyl groups, so that would indicate that 2-methyl-2-phenylpropane would be the most reactive, but benzene is the answer for the question. Thanks in advance!


texts: Alkali Metal Rosinates Solubility in Acetone

texts: In violin finishing technology alkali metal Rosinates are used in varnish synthesis. Usually this alkali metal Rosinates are soluble in Turpentine. I also know that Copper, Zinc Rosinates are soluble in Diethyl ether. However, beside Turpentine I want to know if this alkali metal Rosinates ($\ce{K,\ Na,\ NH4+}$ - Rosinates) are soluble in Acetone especially or in Diethyl Ether or in any other  VOC’s?


texts: Why is 3,6-dimethylpiperazine-2,5-dione optically active in spite of having a centre of symmetry?

texts:
I learnt in my chemistry class that if a molecule has an element of symmetry (either a plane of symmetry or a centre of symmetry), it will not be chiral and hence will not show optical activity.

My professor told me that in alanine anhydride the carbon atoms with methyl groups would be non-planar, hence it will be non-symmetrical:

But if I consider one of the above-mentioned carbon atom above the plane of the ring, and the other below the plane of ring, a centre of symmetry will still exist. Where am I going wrong?


texts: Why is C2H5 a stronger +I group than CH3?

texts:
While reading about the basic character of amines, I came across a note which said that $\ce{CH3-CH2-NH2}$ is more stable than $\ce{CH3-NH2}$ as $\ce{C2H5}$ is a stronger +I group than $\ce{CH3}$.
However, according to what I know, isn't $\ce{CH3}$ a stronger +I group as in a longer chain the +I effect dies out?