texts: How to estimate gas yield from polarization curve of the electrolyser

texts:
A good characterization of electrical properties of the alkaline water electrolysis of the water is its polarization curve.
Is there a reasonable way to estimate gas yield for each point of the polarization curve?
Is it sufficient to estimate the effective power used for splitting by multiplying reversable voltage and the current. And by using gibs free energy of the water splitting one can obtain theoretical gas yield. But is this a reasonable estimate of the actual yeld?


texts:
Franck-Condon overlap integrals are given by $\langle\psi^e_{v_e}|\psi^g_{v_g}\rangle$, where $\psi^e_{v_e}$ and $\psi^g_{v_g}$ are the vibrational functions for the $v^{th}$ vibrational states of the excited and ground electronic states, respectively.

Why is it considered difficult to obtain Franck-Condon factors (judged by the fact that there is a lot of literature dedicated to their calculation) – is the problem only in obtaining high-accuracy vibrational wavefunctions for the two electronic states, or there something else at play?
If you can obtain both $\psi^e_{v_e}$ and $\psi^g_{v_g}$, could you calculate the overlap integral in Cartesian coordinates?


texts: Question about a line from Rosenfeld's paper on optical rotation

texts:
There are a lot of papers on optical rotation which cite Rosenfeld's (German) 1928 paper "Quantum mechanical theory of natural optical rotation..." [Quantenmechanische Theorie der naturlichen optischen
Aktivitat von Flussigkeiten und Gasen, Zeitschrift für Physik, Volume 52, Issue 3-4, pp. 161-174] as background. Here is a paid link--

Apologies that I cannot link to the paper. I have a paper copy and can't find a paywall-free version.

The symbols below are: $\lambda$--wavelength; $c$ is the speed of light; $\nu$ is frequency; $n$ is the index of refraction; $\rho$ is a quantity that does not change between equations (42) and (43).

The last two equations in that paper (42), (43), are a conclusion about an angle of rotation $\theta:$

$$\Delta n = \frac {2\pi ~\rho}{\lambda~ n} \tag{42}$$

and

$$\theta = \frac {2\pi \nu~\cdot \Delta n}{c~\cdot ~ 2} = \frac{2 \pi^2\rho}{\lambda^2} \tag{43}$$

My question is pretty dumb. If we insert the expression for $\Delta n$ into the equality in (43) we get:

$$\frac{2\pi\nu}{c}\cdot \frac{2\pi \rho}{2\lambda~ n} = \frac{2\pi^2\rho}{\lambda^2}\to \frac{\nu}{c~n}=\frac{1}{\lambda}\to\lambda =\frac{cn}{\nu} $$

We know already--and Rosenfeld mentions this a few lines up and at eq. (21)--that

$$\lambda = \frac{c}{\nu~n}$$

which forces $n$ to be $1$. In general $n \neq 1$.

Can someone tell me what, if anything, has gone awry here?

Edit: After looking at several versions of Rosenfeld's equation I see $\theta$ is proportional to the trace of the rotation matrix...the constant of prop. can take various forms and is not the focus of this approach.


texts: The weedkiller paraquat can be produced from methyl-pyridinium chloride using a cyanide catalyst: what is the mechanism?

texts:
Paraquat is 4,4'dipyridinium chloride. There are two common ways to synthesise it starting with pyridine.

In one reaction that can be done on a large scale in water or liquid ammonia, methyl-pyridinium chloride is reacted with a base and catalytic amounts of sodium cyanide in the solvent to give a dimeric intermediate that oxidises easily into paraquat.

What is the chemical mechanism of the dimerisation reaction?


texts:
Many of my students get chlorine $\ce{Cl}$, confused with carbon monoiodide $\ce{CI}$, despite my promises to use serif fonts whenever possible and to never give them carbon monoiodide in a question.

Everything I know about chemical bonding tells me carbon monoiodide should not exist ($\ce{CI4}$, sure), but weird things happen sometimes. My only results from internet searches for carbon monoiodide bring up a set of Quizlet flash cards.

Will my students prove me wrong if I tell them that carbon monoiodide does not exist (except possibly in extreme laboratory conditions).


texts: I was looking for a conductive hydrophobic material if there is one? If not why? I was researching and I found some material about laser etching on metals that causes superhydrophobicity but that I don't think will work if I wanted a curved surface since its roughness would be smoothed out I think. Please correct me if I'm wrong.


texts: Chemical Reaction Alternative to O2 Respiration in H2/N2 Atmosphere

texts:
Note: If this question does not belong on this Stack Exchange, please direct me to a more appropriate Stack Exchange.

This is a "creative chemistry" question as much or more-so than a "give me the facts" type of question. Should be of interest to anyone who finds the topic of plausible alternative biochemistries intriguing.

I recently came across several papers outlining a hypothetical type of photosynthesis that would be highly efficient in a Hydrogen ($\ce{H2}$) dominant atmosphere containing Methane ($\ce{CH4}$). The photosynthetic reaction is:

$$\ce{CH4 + H2O + $y$ -> CH2O + 2H2}$$

"$y$" represents energy imparted by photons. "$\ce{CH2O}$" is the simple organic compound formaldehyde, which could be used to build biomass.

This made me wonder how "animals" in such an environment would obtain the energy needed to live. In an "$\ce{O2}$" heavy atmosphere the answer is simple: use "$\ce{O2}$" to oxidize the available organic compounds, getting a ton of energy. This is aerobic respiration. What if there is essentially zero available "$\ce{O2}$"? Which brings me to...

My question in detail: What is a plausible chemical reaction (or series of reactions) that could take the place of $\ce{O2}$ respiration in a "Hydrogen Dominant" world with the following molecules and compounds to work with:

ATMOSPHERE

$\ce{H2}$ (10-90%)
$\ce{N2}$ (10-90%)
$\ce{H2O}$ Vapor (≈1%)
$\ce{CH4}$ (0.01 - 5%)
$\ce{NH3}$ Vapor (0.01 - 5%)
Other trace to minimally-present compounds may include $\ce{CO2}$, $\ce{Ar}$, etc.

BIOMASS

Built off of $\ce{CH2O}$ (the organic product of hydrogenetic
photosynthesis)

WATER & LAND

Bodies of water containing a mix of  $\ce{H2O}$ + $\ce{NH3}$, and plausibly available compounds in the crust (like iron).

By "take the place of" I mean provide enough energy to run complex life-processes. I do not mean superficially resemble aerobic respiration (i.e. The process need not require the "breathing in" of atmospheric gases. It could, but need not).

The answer should try to meet the spirit of the following criteria:

The reaction(s) could make use of compounds in the air (breathing) or could be obtained through other methods (eating, drinking) in sufficient quantity to run biological processes.
Impart significant amounts of "free" energy, more so than other plausible reactions.
Make use of available compounds (see details above).
Plausibly occur at temperatures and pressures not inimical to carbon life. $\pu{500\\K}$ temperatures or pressures of $\pu{100\\bar}$ are no-goes.
Be "plausibly likely" to evolve. This requires a measure of judgement. If the chemical reaction or series of reactions is wildly complicated, far-less efficient than other alternative reactions, or needs to make use of rare materials, then it's probably not plausible.

I'd love the form of the answer to contain the equation, a brief discussion on why it's plausible, and a discussion of the amount of energy released, and/or other "good to know" things.

Thanks!

References:

Photosynthesis in Hydrogen-Dominated Atmospheres – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4284464/

BIOSIGNATURE GASES IN H2-DOMINATED ATMOSPHERES ON ROCKY EXOPLANETS – https://iopscience.iop.org/article/10.1088/0004-637X/777/2/95/meta

A BIOMASS-BASED MODEL TO ESTIMATE THE PLAUSIBILITY OF EXOPLANET BIOSIGNATURE GASES – https://iopscience.iop.org/article/10.1088/0004-637X/775/2/104#apj480437s4


texts:
I just bought a heat bag from store and it has special property.

It is made up of transparent plastic bag and transparent unknown liquid inside when sold. There is a tiny circular metal piece in there. If you bend the metal piece, crystalization will occur and release quite a lot of heat. The crystalization will spread out and change all the liquid into crystals.

When the hardened plastic bag cool down, you need to put it into boiling water and the crystals will dissolve and become liquid again.

What is more interesting, I tried to heat it up but not letting all the crystal dissolve, take it out of the boiling water and assume it is ready for the next use. However, the half-dissolved liquid/crystal turns into all crystals again (without me bending the metal piece). I am guessing the transformation was not complete and the process was reverted.

Did the Japanese invent this material?


texts: Why are potential electrolytes poor conductors in the pure liquid state?

texts:
In my textbook, "In the pure liquid state, a true electrolyte is a good conductor of electricity. In contrast, a potential electrolyte is a poor conductor in the pure liquid state."
 definitions
"A true electrolyte consists of ions in the pure state. Most salts are true electrolytes. A crystal of NaCl, CuSO4, or MgS consits of positive and negative ions."
"A potential electrolyte consists of uncharged molecules in the pure state, but when dissolved in a solvent, it reacts with the solvent to some extent to yield ions"


texts: The influence of lemon juice & sugar on the ph-value

texts:
If I add equal amounts of lemon juice and sugar into water, does the ph-value remain unchanged, as both cancel each other out?

This question arose in my head as I learned that pouring milk into coffee increases the ph-level of the beverage making it taste less sour (You might want to check out the following video at 5:43: https://www.youtube.com/watch?v=eTYsQUqodeE; it's in German but you will get the overall point, I'm sure).

Now, if I add lemon into my tea, it tastes more acidic, so the ph-value would be more acidic right? If I add additionally some sugar, the tea tastes not sour anymore. So, I wonder if sugar is able to make a acidic drink more alkaline as it tastes less acidic...Or am I comparing apple with pears?

(Sorry, if my question sounds a bit unscientific...)


texts: Is every chemical reaction in equilibrium?

texts: I read that every chemical reaction is theoretically in equilibrium in an old textbook. If this is true how can a reaction be one way?


texts: Synthesis of hydrazine with bleach and ammonia

texts:
I am trying to make rocket fuel using hydrazine, hydrogen peroxide and home products. I want to put an action figure in orbit.

Is there any way to synthesize hydrazine with bleach and ammonia, using $\ce{H2SO4}$ as a catalyst?


texts: What is the signal at around 2090 wavenumbers in the nitroguanidine FTIR spectrum?

texts:
There is a signal at around 2090 apparent in the FTIR spectrum of nitroguanidine  from Sigma-Aldrich (first image). It's also apparent in FTIR spectra we've taken in the lab (second image), but when assigning peaks to bonds, we are unclear to what it is.

We are unsure of how Sigma-Aldrich prepared their pellets, but we used KBr. We are thinking perhaps KCN, but then again - how could that possible form?


texts: Which among phenol and 1,2-dihydroxybenzene has the higher boiling point?

texts:
My attempt

Based on symmetry: I think that looking for symmetry phenol has a higher boiling point than 1,2-dihydroxybenzene because the two -OH groups projecting out from the benzene ring of 1,2-dihydroxybenzene will not allow close packing of them which results in a lower boiling point.

Based on hydrogen bonding: In this sense phenol would have a lower boiling point because 1,2-dihydroxybenzene would have more inter-molecular hydrogen bonding than phenol.

How do I know which factor wins?


texts: How to increase the conversion for the reaction between 2-acetylpyridine and diamine?

texts:
I tried refluxing in toluene using activated molecular sieves to absorb any water produced (didn't use Dean-Stark trap as it's a very small scale reaction).

This reaction isn't going by changing the time or temperature conditions. So, I added some (0.5 equivalent) triflic acid to increase the electrophilicity of the carbonyl. The reaction is proceeding but conversion isn't high. Is triflic acid a good choice for this reaction? Should I try using equivalent amount of triflic acid to increase the conversion?


texts:
Let's take
$$\ce{3HCl + Fe(OH)3 -> FeCl3 + 3H2O}$$
This would be a normal one-way neutralisation reaction.

How about hydrolysis of ferric chloride (technically iron(III) chloride)?

$$\ce{FeCl3 + 3H2O <=> 3HCl + Fe(OH)3}$$

As this is reverseable, we should be able to right it with the reactants and products flipped.

$$\ce{3HCl + Fe(OH)3 <=> FeCl3 + 3H2O}$$

Now that is nothing but our original reaction …
Why aren't neutralisation reactions reversible?

Also, does anyone have any good links to chemical equilibrium as in comments?


texts:
A type of Krazy Glue changes from purple to clear when it dries. What is the chemistry behind the color change? Is it due to a particular compound only found in this particular Glue?

A description of glue can be found on their website.


texts: Why is picric acid more acidic than carbonic acid?

texts:
I just had a question in a test asking to compare the relative acidity of picric acid (TNP) and carbonic acid, $\ce{H2CO3}$ (not phenol). It turns out that TNP is more acidic. I have no idea why? Is there some rule I'm missing or is this one of those exceptions that I just have to remember?

I have been told that alcohols are generally less acidic than carboxyl groups. But in this case, doesn't the hydroxyl group form a chelate ring already? If the stability of the reactant is much greater than the the stability of the product, why would the reaction even take place? Sure, there is cross conjugation in carbonic acid, but shouldn't it be extremely hard to break the chelation in picric acid?


texts: When (R)-2-bromopentane reacts with sodium methoxide, what is the major product?

texts: I know that with a SN2 reaction mechanism this becomes (S)-2-methoxypentane, but with elimination this is trans-2-pentene. I know that elimination happens quickly when you apply heat. In this case we have a secondary alkyl halide so its possible to use SN2 or E2 due to methoxide being a strong nucleophile.


texts: Why do different H+ in polyprotic acids have different K?

texts:
Why do different $\ce{H}$ atoms in a polyprotic acid have different values of $\pu{K_a}$?

All $\ce{H}$ atoms (which can show acidic nature) have similar properties within the molecule. It does not matter which one reacts. For example, in $\ce{H3PO4}$, all the $\ce{H}$ atoms can be dissociated from the molecule to act as acids. All of them are attached to an $\ce{O}$ atom, which is attached to the central $\ce{P}$ atom. If all the properties are same, then why is $\pu{K_a}$ different?

`


texts:
I read this statement that:

  Xenon is the most soluble noble gas in water.

My first doubt is:
Why does the solubility of noble gases in water increase down the group?

Even if this is the trend, why is Radon not considered most soluble?


texts: Does the non-serotonin-like half of LSD resemble anything of significance?

texts:
LSD's resemblance to serotonin explains many of its effects on the brain, but I noticed only half of it resembles serotonin. The question I have, is does the other half resemble anything, particularly anything of significance?
In this image the bottom half resembles serotonin:

In this image, the other half is shown, and I wonder if there's anything that it resembles.

[Image by By Ben Mills - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=14584151]


texts: Does water self ionize to protons or hydronium ions, or both?

texts:
The most common equation for the self ionization of water I've seen is with protons and hydroxyl ions as products.

H2O ⇌ H+ + OH-

I've also seen the following equation with hydronium ions as a product instead of protons

2H2O ⇌ H3O+ + OH-

Does the first equation actually happen, or is it just an abbreviation for the second? Or do both species (hydronium and protons) exist in solution, or something more complicated?


texts: Why is a very small peak with larger m/z not considered to be the molecular ion?

texts:
With regards to the following spectrum:

When asked for the M/Z for the molecular ion, the peak at 58 was taken, not 59.

What causes the peak at 59, and why isn't it taken as the molecular ion?


texts: Core cutoff radius and energy cutoff radius in pseudo potential DFT

texts:
From what I understand the core cutoff radius is the distance where the pseudo wavefunction and the full electron wavefunction start to resemble each other. In other words, the pseudo wavefunction and full electron wavefunction have the same energy and electron densities for distances larger than the core cutoff radius. The energy cutoff radius is the energy that determines the size of the plane wave basis set.

My question is how they are related. Most computational software control the energy cutoff radius, and the energy cutoff radius is lower for ultrasoft pseudopotentials. My question is why is this so? I understand conceptually that ultrasoft pseudopotentials are smoother. Hence the Fourier series is less complicated. Hence the basis set does not need to be large. However, I have trouble putting this vague (if correct) concept into concrete reasoning. What are relevant equations that directly relate the energy cutoff and core cutoff?


texts: Reaction between 1,2-dicyanoethylene and 2-phenylbuta-1,3-diene in toluene and heat

texts:
I believe this may be a Diels-Alder reaction, but the benzyl group on the edge does not serve a an electron donating group and more as a stabilizing group.

I am at a loss for what reaction would take place if the Diels-Alder reaction doesn't.


texts: Why ionisation enthalpy of early lanthanides are expected to be greater than early actinides?

texts:
In my book Chemistry Part I (NCERT XII), a statement on p. 232 goes like this:

  It is evident from the behaviour of the actinoids that the ionisation enthalpies of the early actinoids, though not accurately known, but are lower than for the early lanthanoids. This is quite reasonable since it is to be expected that when 5f orbitals are beginning to be occupied, they will penetrate less into the inner core of electrons. The 5f electrons, will therefore, be more effectively shielded from the nuclear charge than the 4f electrons of the corresponding lanthanoids.

My thought on this matter is that $Z$ will increase and f-orbitals will shield electrons poorly and so ionisation enthalpy should increase. But I'm not able to understand what my book is trying to say. What is meant by less penetration to inner core of electrons? To be honest I wasn't able to understand all the above mentioned 3-4 lines. So, can anyone explain this properly to me, please?


texts: Why is the formation of NaCl an exothermic process?

texts:
My book says,

  When NaCl forms, what really happens is that $\ce{Na+}$ and $\ce{Cl-}$ come together and form an ionic bond and thus NaCl is formed and it is a quite exothermic reaction.

Why and from where is this energy coming from? Ok Ok, I read that every system wants to reduce energy, but where literally is this energy coming from, is it because of some electrons or from the nucleus? Or from where?


texts: Is a carbon-fluorine bond stronger than a carbon-chlorine bond?

texts:
In hydrolysis/nucleophilic substitution of haloalkanes, the bond enthalpy indicates the rate of hydrolysis (e.g. the $\ce {C-I}$ bond is weaker than the $\ce {C-Cl}$ bond so in hydrolysis the alkane with the $\ce {C-I}$ bond will break more quickly and react with the $\ce {OH-}$ ions)

However, in free radical substitution reactions, if you have a molecule like $\ce {CCl2F2}$ , then is the $\ce {C-F}$ bond stronger or weaker than the $\ce {C-Cl}$ bond (so which will require less energy to break)?


texts: Cp-Cv For a gas following Van Der Waal equation of state

texts:
How do you derive the relation

$$C_p-C_v= R\left(1 + \frac{2a}{RTV}\right)$$

for a gas obeying van der Waals equation of state? Any leads?


texts: What Causes Atomic Orbitals to Hybridise?

texts: I'm finding it difficult to visualise the process of hybridisation. Taking the example of formation of $\ce{CH4}$, can it viewed as the collapsing of the p orbitals of the Carbon atoms as they get "heavier" on excitation even before the introduction of Hydrogen atoms or is it the collision with Hydrogen atoms that causes the fusion?


texts: Why is tert-Butyl (tBu) often not listed as protecting group for alcohol?

texts:
I am not seing tBu listed as alcohol protection group in all of these places:

https://en.wikipedia.org/wiki/Protecting_group#Alcohol_protecting_groups
http://www.synarchive.com/protecting-group/
http://www.organic-reaction.com/organic-synthesis/protecting-groups/ether/

On the other hand it seems to be quite common in peptide synthesis to protect the alcohol of serine, threonine and tyrosine with tBu.

It is listed on the German Wikipedia page: https://de.wikipedia.org/wiki/Schutzgruppe#Alkohole

Can I conclude from this that tBu is very rarely used in non-peptide syntheses? Or is it just plain missing from the English Wikipedia article?


texts:
What is the shape of the $\ce{C2H2}$ molecule?

The fact that is has a triple covalent bond between the 2 carbon atoms and 2 other bonding pairs between the hydrogen and carbon atoms leads me to believe that it could be linear shape.

However, I'm not sure if the triple bond counts as a single electron bonding pair or 3. If it counts as 3 bonding pairs then the molecule would have 5 overall, and therefore be a trigonal bipyramidal shape.

So is it octohedral or linear? Pretty sure it's linear


texts: I am looking to add caffeine powder in pure form to water that has a pH level of 7 or higher. What would the pH level be if I do this? Is Caffeine itself acidic?


texts: Although I am now taking a pretty fundamental chemistry course, I am really looking to gain an extremely comprehensive knowledge of the subject, specifically, in inorganic and organic chemistry. I am looking for two texts, keeping in mind that the most important thing is comprehensiveness and the most information about the most topics, not ease of readability. I have the time and dedication to do it, but I really don't want to start with a book that doesn't cover everything and I have to fill in the holes as I go or individually seek out topics it misses.


texts: Transformation of an epoxido-carboxylic acid to an aldehyde

texts:
So I am battling with the last part of this transformation and was hoping someone could explain this mechanism to me so that I can confirm my answer.

Treating an alcohol with a strong hydrohalic acid results in the formation of alkyl halide and proceeds through an SN1 mechanism. (Protonation of alcohol on the carboxylic acid, then loss of $\ce{H2O}$ to form a carbocation) But $\ce{HCl}$ is supposed to give a substitution reaction and not an elimination reaction. So I am unsure how the final product is formed.


texts: How do you calculate the heat of a reaction given a table of heat of formation values?

texts:
So I've been trying to answer this question, and as far as I've learned it's $\Delta H^0_{\mathrm f}$(products)-$\Delta H^0_{\mathrm f}$(reactants), multiplying each by number of moles and such.

Trying to use that on this problem I came up with $\ce{0.008 OH- + 0.008 HCO3- -> 0.008 H2O + 0.008 CO3^2-}$ after (possibly incorrectly) noting that $\ce{HCO3}$ was in excess. However, this does not yield anywhere near the correct answer of C. What am I doing incorrectly?


texts: Colour change when excess ammonia added to [Cu(H2O)6]2+

texts: Since ammonia is a stronger ligand than $\ce{H2O}$ shouldn't the colour of the new solution $\ce{[Cu(NH3)4(H2O)2]}$ be lighter as the energy gap will be higher and so light with higher frequency and energy (between blue and indigo) be absorbed which means that the transmitted light is the one between blue and green which is lighter? Why does the solution turn deep blue?


texts: Why are s orbitals more “penetrating” than p orbitals?

texts:
In polyelectronic atoms, the reduction in the net central force due to electron-electron repulsion is accounted for through an effective nuclear charge that depends on a “shielding effect” of inner electrons.
The reason for the splitting of energies of orbitals in the same quantum shell (s<p<d<f) is usually given that s orbitals are more "penetrating" i.e have a greater probability density near the nucleus, so experience less shielding and thus a greater effective nuclear charge.
However, I can't understand why a comparatively larger p. density is used to measure the penetrating power. the mean orbital radius actually decreases from s to f orbitals. Sure, s orbitals have a relatively higher p.d near the nucleus but the rest of the p.density is also relatively more further away than that in p,d or f orbitals. Using the mean distance as the appropriate measure, shouldn't the energy be in the order f<d<p<s?
the only explanantion that comes to mind is that the decrease in energy from being unusually close some of the time outweighs the decrease in energy due to being more farther away for the rest of the time (and thus on avg), but this is just a guess and a rather non-intuituve explanation


texts: Why is it necessary to measure the NMR frequency relative to a standard such as TMS?

texts:
The horizontal axis of an NMR spectrum is "chemical shift". A standard environment such as tetramethylsilane is chosen as the zero of chemical shift. The frequency at which resonance occurs for other environments is then measured relative to the frequency at which resonance of the standard environment occurs e.g. a particular environment might resonate at a frequency 1ppm lower than standard environment.

Why can't we measure the frequencies at which resonance occurs absolutely, not relative to a standard environmnent? Then we would have a horizontal axis of frequency instead of chemical shift.


texts: Wasn't Rutherford's assumption of gold foil to be made of single layer wrong?

texts:
My teacher taught about Rutherford's gold foil experiment today. Sir said that, Rutherford used gold foil of thickness $10^{-7}$ m and concluded atom to be of size $10^{-10}$ m. Sir also said that Rutherford assumed foil to be consisting of only single layer of gold atoms.

What I thought was, if Rutherford used gold foil of $10^{-7}$ thickness, which is greater than the size of atom [$10^{-10}$] which he had concluded. So, gold foil should be made of more than single layer of atoms. But this would be against his assumption. If we assume gold foil to be consisting of more than one layer of gold atoms. Then we will be in need to know the structure of gold, i.e to know whether it has atoms in ABAB.. or AAAA.. or ABCABC... type of arrangement. My book says that gold has ABCABC... or ccp arrangement, it mean that there is no vertical allignment of atoms, thus there will be no vertical allignment of nuclei. It makes significant changes to Rutherford's predictions with respect to deviations. Won't it?


texts:
Consider the addition of HBr (in absence of any radical initiators or environment that promotes radical mechanistic pathway), to 3-bromocyclopentene.

The first step is the attack of $\ce{H^+}$
On the exposed π electron cloud. But my query is whether it forms a classical carbocation like this one to oppose the negative inductive effects of the halogen atom:

Or does it proceed with the formation of bromonium ion like this one to partially complete its octet using lone pairs on Br.

These two would lead to different products but I'm interested in the major one.
The first one would lead to 1,3-dibromocyclohexane, while the second one would lead to 1,2-dibromocyclohexane.


texts: How can the bulky octadecyltriethoxysilane molecule promote single-crystal growth?

texts:
Octadecyltriethoxysilane is very bulky (source),

yet it was used to promote single crystal growth (source). How can such a bulky molecule induce crystal growth? (For example epitaxial growth happens only when both materials have similar unit cell dimensions.)


texts: Gas chromatography flame ionization detector (FID) - why hydrogen gas?

texts:
Why is $\ce{H2}$ used in an FID, apart from the fact its combustion does not contaminate the flame?

In other words, is the temperature of the flame important or critical? Is the stability of the temperature?


texts: A first-order reaction at infinite concentration

texts:
I have a first-order reaction, for the binding of two molecules, of the form: $\text{k}_\text{f} = \ce{k_1 (M*s)^{-1}}$.  What happens at infinite concentration?  How is this upperbound typically handled for approximations in chemistry?  Do we need to measure additional kinetics parameters in this regime?

If anyone has any specific knowledge, I'm particularly concerned with DNA hybridization, where we have $\text{k}_1 \approx 10^6$.  Will we simply converge on the elementary step time for the formation of a base $\text{k}_+ \approx 10^6$ to $10^7$ (Craig et al., 1971; Porschke & Eigen, 1971)?  It seems reasonable to me that as $\text{C} \to \infty$ we'd have $\text{k}_\text{f} \to \text{k}_+$, which, I'd guess is the point where the rate limiting step is the time for the molecule to sample different rotamer/etc. configurations.  Perhaps it isn't an accident that these orders of magnitude match up?

Also, should we think about the entropy of complex formation in the same way in the limit of infinite concentration?  My guess for this would be "yes" since the entropic penalty of holding two molecules together, derived from studies on monoatomic gases, should be concentration independent as long as diffusion/mixing is allowed.  In practice, however, we'll probably have a gel at these higher concentrations.


texts:
Can someone provide reliable data on the solvation / hydration enthalpies of $\ce{Ti^{4+}}$ and $\ce{Cr^{3+}}$ ions, or explain which is more stable qualitatively? According to this article1

CFSE in $\ce{Cr^{3+}}$ is around 59.7 kcal = 249.7848 kJ

and according to the abstract of an article by Uudsemaa and Tamm,2 the estimated hydration energy of $\ce{Ti^{4+}}$ is around 7800 kJ/mol

Is this data correct? can someone explain qualitatively as well?

References

(1) http://hydration%20energy%20of%20Cr3+%20value

(2) Uudsema, M.; Tamm, T. Calculations of hydrated titanium ion complexes: structure and influence of the first two coordination spheres. Chem. Phys. Lett. 2001, 342 (5–6), 667–672. DOI: 10.1016/S0009-2614(01)00617-0.


texts:
I am talking about the standard fats we see in everyday use (triglycerides). It seems that no matter what the composition, saturated or unsaturated, all fats are glossy when liquid. I don't know if this extends to other esters, as I have seen only few of them.

What gives fats this shiny look?

Sorry if the question appears unresearched, but all my attempts to combine "fat" and "glossy" in a search query resulted in nutrition advice.


texts: How to identify the aromatic compound with the sum formula C7H6Cl2?

texts:
An aromatic compound (A), $\ce{C7H6Cl2}$, gives $\ce{AgCl}$ on boiling with alcoholic $\ce{AgNO3}$ solution and yields $\ce{C7H7OCl}$ on treatment with $\ce{NaOH}$. (A)  on oxidation gives a mono-chlorobenzoic acid which affords one mono-nitro derivative. Find the Compound (A).

Here from $\ce{C7H6Cl2}$ we can say it is a benzene derivative. Now as only one chlorine atom reacts with $\ce{AgNO3}$, one chlorine atom is directly connected to benzene and one is connected to methyl group which is connected to benzene. But how to find where the $\ce{-CH2Cl}$ is situated, i.e. ortho, meta or para?


texts:
I was trying to synthesize 1-iodo-4-nitrobenzene in the lab today – however, the appearance of my product really confused me.

At first, I added conc. sulfuric acid to water and 4-nitroaniline.
This was followed by diazotising the amine sulfate with sodium nitrite and water. (This was done at temperatures of below $10\ \mathrm{^\circ C}$).

Then, I added the diazonium salt to a solution of $\ce{NaI}$ and water. A large plume/foam formed ($\ce{N2}$). After, I performed a filtration using a Büchner funnel. That’s where things went wrong.

I used water to wet the filter paper. I added in the iodonitrobenzene. A suckback occurred within a few seconds as the product was quite viscous. After resumption, the filtration went as planned. However, the product on the filter paper was a molten brown mush.

I tried to let it dry for a further 5 minutes but once turned off it remained a sludge.

Do you have any suggestions on how I could improve on this synthesis or maybe an idea of what went wrong?


texts: Calculating the pH of a highly dilute solution of HCl

texts:
For relatively high concentrations of $\ce{HCl}$, I usually just assume that $[\ce{H+}] = [\ce{HCl}]$, because $\ce{HCl}$ is a strong acid and is completely ionized in solution. By taking the negative logarithm of the concentration of $\ce{[H+]}$, the pH comes out more or less correctly.

However, at very low concentrations, this method doesn't work out so well, because water has an amount of auto-ionization, which is described by $K_\mathrm{w} = 10^{-14}$. My old method was just to say that

$$[\ce{H+}] = [\ce{HCl}] + \pu{10^-7 mol dm-3},$$

to include the auto-ionization of water in my calculations. I can't really describe why, but I believe this method to be wrong, because the number $\ce{10^{-7}}$ comes from water just by itself, not with $\ce{HCl}$ added to it.

Then I came across this website, which implies that the above method is an OK method, but mentions that "However, that more complex technique will not be discussed here.". What is that 'more complex technique', and how could I use it?


texts: How do you purify gases formed in electrolysis with a potassium hydroxide electrolyte?

texts:
I am interested in the $\ce{KOH}$ vapor that is released with my gasses during electrolysis.
I have two questions.
What would be the best place to start research on the $\ce{KOH}$ vapor produced in electrolysis and how to separate the $\ce{KOH}$ vapor formed.
I was thinking about filters, or bubblers that require constant water replacement. For me, a bubbler is a jar with a gas inlet at the bottom and gas collection at the top.
Also I have no clue on what type of filter to use since I don't know where to start research on $\ce{KOH}$ vapor.
My goal is to make the gases safer by eliminating most of the $\ce{KOH}$ vapor. I will probably use a pH testing paper to test the air to see if $\ce{KOH}$ vapor is present.


texts: Why are MD (Molecular Dynamics) simulations performed at room temperature for the purposes of studying proteins?

texts:
All of the MD simulations which are cited in the literature seem to be performed at room temperature (~300 Kelvins), while enzymes are usually bioactive at body temperature (~310 Kelvins).

I am wondering why not just use 310 K for the MD simulation? I suspect it is because most water models are designed specifically for room temperature (ie. TIP3P waters).


texts: Mechanism of initiation in contact explosives?

texts: It's well known that undiluted nitroglycerin will explode when subjected to a physical shock.  What is happening as a result of the physical shock that sets off the explosive reaction?  In particular, why doesn't it explode spontaneously at room temperature without a physical shock?


texts: How does lansoprazole degrade in acidic conditions (mechanism)?

texts: Can anybody help me and explain the mechanism of reaction here? And also I was wondering when disulfide bond is made, can molecule dissociate, return to the previous state and make a disulfide bond when it gets to acidic environment again?


texts: Determination of pKb of a mono acidic base

texts:
$20$ mL of a weak monoacidic base($\text{BOH}$) requires $12$ mL of $0.3$ M $\text{HCl}$ solution for the equivalence point. During titration, the pH of the base solution was $10$ upon the addition of $4$ mL of $0.3$ M $\text{HCl}$ solution. What is the $\text{pKb}$ of the base($\text{BOH}$)?

My attempt:

The concentration of the base is given by,
$c * 20 = 12 * 0.3$ -- (equating the moles of the acid and base)
$c = 0.18$ M

So, initial moles of the base in the container $= 20 * 0.18 = 3.6$ mmol
Moles of acid that is added $ = 4 * 0.3 = 1.2$ mmol

Since the base is monoacidic, they will react in a 1:1-mole ratio. The acid is the limiting reagent, so it will be fully consumed. Therefore the moles of base left is,

$3.6 - 1.2 = 2.4$ mmol

The concentration of the base is,
$\frac{2.4}{24} = 0.1$ M

Since the pH of the solution is $10$, therefore the concentration of $\text{OH}^- = 10^{-4}$

Applying the approximated formula for calculating the $\text{k}_b$ of a weak base,

$$\text{K}_b = \frac{x^2}{c}$$

Where,
x = concentration of $\text{OH}^-$ ions
c = concetration of the base

In our case,
x = $10^{-4}$
c = $0.1$

Plugging in the values I got $pK_b = 7$. But the answer is given $4.3$.

Any help would be appreciated.


texts: Role of substituents in radical initialized polymerization

texts: Here, the answer given is (iv), and I don't see the reason why methoxyethene is not forming an addition polymer with radical initiators. Clearly, the first option will form polystyrene and the second, polyacrylonitrile. But after that, I feel lost. After looking at the answer key, I felt that there would be some role of the OCH3 here as it may react with the peroxide initiator, but I'm not quite sure what. As far as I know, the radical is generated at the double bond which then keeps polymerizing independent of the substituent. Can somebody tell me what is the mechanism of polymerization in the (iv) part?


texts: I assumed the the $\ce{TsOH}$ would dissociated to produce hydronium ions that would protonate the carbonyl. This would make the carbon more delta + and so susceptible to attack by $\ce{MeOH}$. After proton exchange I thought the $\ce{H2O}$ group would leave and we would have a carbocation left over. I can't work out how to resolve this carbocation with the changes in double bonds.


texts: Do all the angles change in cyclopropane and cyclobutane or it is only the C-C-C angles?

texts: Are the angles other than the C-C-C angles in cyclopropane and cyclobutane still 109.5° as the acyclic compound, or what?


texts: Why should we be interested in catalyst for electrolysis?

texts:
I've been reading papers on Phosphided metals (CoP, NiP, FeP) as a catalyst for electrolysis.  They increase the current density of the cell for a voltage.  If it still requires 39.4 kilowatt-hours per kilogram of hydrogen (https://en.wikipedia.org/wiki/Electrolysis_of_water), why does it matter how fast the reaction occurs?

For example, with no catalyst, an electrolyzer runs at 0.6A/cm2 at 2.3V or with a catalyst it runs at 1A/cm2 at 1.4V.  Both cases require about the same amount of power and should produce the same amount of hydrogen, correct?


texts:
While drinking milk (or better 'while seeing the milk I'm gonna drink') a question came up to my mind:

Why does the milk sometimes flake, even if not in contact with some other substances?

I guess the correct term to use is flocculation, at least this is the word that raises up when talking about cheese production. I just learned the word casein. However, my question is not about cheese production.

My question is also not about flaking milk when poured into a cup of coffee which seems to be dependent on the acidity of the coffee. But casein is again the keyword.

I think the answer to my actual question will also contain the word casein, but here's the scenario:

I open a milk carton for the first time. This package doesn't have any hole and the shelf life isn't reached yet. I pour the milk into a clean cup and then observing some flakes at top of the milk.

What I was told as a child, when curiously asking, flaking is an indicator that the milk is getting acid. And in that case the keyword casein would fit again, but there's still one thing why I'm not persuaded: the milk was quite tasty and my stomach also didn't complain about it.

So, what exactly has happened to my milk when I see some flakes on top of it? Is the milk indeed spoiled and I actually shouldn't have drunk it (and just was lucky) or is there anything else which can lead to flakes?


texts: Whilst reading about stereochemistry, I came to know that the stability and melting point of cis isomers is lower than trans isomers. By searching on net I've found the reason behind that. But one question arises - why is the internal energy of cis isomers bigger than of trans isomers?


texts: Changing iron(III) acetate to iron(II) acetate

texts:
Is there a way simple way to turn iron(III) acetate into iron(II) acetate or vice versa?

Edit (as per answer below): an oxidiser like hydrogen peroxide will turn iron(II) acetate into iron(III) acetate. A reducer (not sure what household product) will do the reverse.

Some background: my partner soaks scrap cast iron in white vinegar for several weeks and then uses the resulting liquid as a mordant for dyeing. According to wikipedia's page on iron acetate, soaking iron in vinegar creates a mix of iron(II) acetate and iron(III) acetate. As I understand it, the oxidation state of the iron used as a mordant effects the colour of the dye on the fabric. As such, it would be nice to be able to experiment with just iron(II) or just iron(III). Is this possible to achieve using household chemicals?

Even more background: The dyeing process is soak fabric in mordant water. Dry fabric. Wrap fabric with leaves and place in boiling water. Unwrap and admire beautiful prints :)


texts: Why is there only one ionization isomer of [Cr(NH3)5(NO2)]Cl2?

texts:
How many isomers are possible for $\ce{[Cr(NH3)5(NO2)]Cl2}$? Consider all possible types of isomerism and draw each isomer.

My texbooks presents only three possible isomers: $\ce{[Cr(NH3)5(NO2)]Cl2}$ (the original compound), $\ce{[Cr(NH3)5(ONO)]Cl2}$ (linkage isomerism through $\ce{NO2}$), $\ce{[Cr(NH3)5Cl]Cl(NO2)}$ (ionization isomerism).

However, why is $\ce{[Cr(NH3)5Cl]Cl(NO2)}$ the only possible ionization isomer? Why can't $\ce{[Cr(NH3)4Cl(NO2)]Cl(NH3)}$, $\ce{[Cr(NH3)3Cl2(NO2)](NH3)2}$, or $\ce{[Cr(NH3)4Cl2](NH3)(NO2)}$ form as well.

The proposed ionization isomers were constructed by substituting one, or both, of the $\ce{Cl-}$ ions in the complex ion structure with either $\ce{NH3}$ or $\ce{NO2-}$; the answer seems to indicate that $\ce{NH3}$ cannnot under ionization isomerism with $\ce{Cl-}$.


texts: Carbon monoxide detection without a detector

texts:
I have just been waken up by an alarm and found out that my neighbour did something terrible with his lighter. Luckily, there was no fire, only a plenty of smoke, and our flats were hermetically isolated, so that smoke didn't go to my flat. But, most probably because of my suspiciousness, I noticed some smell of burnt organic, which usually accompanies CO. I switched on ventilation and went out - just in case. There were no CO detectors in the house - only smoke detectors - my bad.
Now the adventure is over (I hope so, at least) and I have got an (im)practical question:

Are there any ways to detect CO using only "kitchen chemistry"?


texts: How does heat transfer between molecules happen in deep?

texts:
Inside the container is cold water and outside the container is hot water. B is the microscopic view of container walls .W is water
And A is hot water.
What I have shown is the microscopic view of container walls(Small part )
A is the surrounding and B is the microscopic view of the walls of container ( Since there is some thickness of container walls and we can say that there are molecules present there ).
As you can see , when cold water molecules apply force on B (walls of container at left side) , B walls also apply force on water molecules and same has happened in the part where there is hot water.This is from the Newton’s third law of motion.
Average Kinetic Energy of water molecules will be less since it is cold water.So less force applied by water molecules on the wall.
Average kinetic energy of hot water will be more than cold water.So it applies more force on walls of container than by cold water.
I hope I have written the things clear till here.
Q1 Is it that the walls container will be pushed by B towards right side and not left side ? Because there is more force by Hot water and not cold water.
Q2 Does heat get transferred here because the Average kinetic Energy of the walls of container will increase due to force of A on B? And those will put the molecules inside B into motion which will further put water molecules  into movement and therefore making heat transfer ?
Q3 Does heat transfer happen only because of this displacement?
HAVE I WRITTEN THE MEHTOD OF HEAT TRANSFER?IF NOT, THEN PLEASE HELP IN CORRECTING ME.
I am trying to make my self understand heat transfer in details.
Please tell if how can I improve the quality of my question if not good.


texts: Nucleophilic Aromatic substitution in 3-Bromoanisole

texts: I came across an example in my textbook where $\ce{3-Bromoanisole}$ is reacted with $\ce{NaNH2}$ in liq. $\ce{NH3}$. My understanding is that the reaction would proceed by a Benzyne intermediate, with the triple bond between $\ce{C2}$ and $\ce{C3}$. Now, I know that the carbanion must be formed where it is most stable. Since $\ce{C3}$ is at meta position with respect to the $\ce{-OCH3}$ group, the electron density there must be lower, and hence that is where the carbanion should be formed, leaving us with the $\ce{-NH2}$ group at $\ce{C3}$, forming a product that will be more stable due to hydrogen bonding between the $\ce{-OCH3}$ and $\ce{-NH2}$ groups. However, in my textbook it says that a meta-substituted product is formed with no explanation. To me, it seems like that would be very unstable as the $\ce{-OCH3}$ group would be increasing the electron density by both resonance and the inductive effect. Can someone please explain what I'm missing?


texts: What effect does Baking Soda and Citric Acid have on a soft drink?

texts:
In chemistry, we are doing a project where we have to make our own carbonated soda. The ingredients our group is using are:

Baking Soda ($\ce{ NaHCO3}$)
Citric Acid ($\ce{C6H8O7}$)
Flavoring powder (ex. KoolAid flavoring
    powder)
Sugar
Water

Using stoichiometry, our group has already calculated how much citric acid we need based on the 1 gram of baking soda that we are deciding to putting in: we have to use 0.76 g citric acid based on our calculations.

My question is, what effect does baking soda have and what effect does citric acid have on the soda? Does baking soda make it "bubbly"? Does citric acid make it more concentrated?


texts: Material that acts as a "sponge" for sulfuric acid?

texts:
I would like help with a materials problem I am looking into that pertains to a product I would like to develop.

What I seek is some kind of substrate that acts like blotter paper does. Ideally, the substrate will be a thin material which can be soaked in sulfuric acid and hold a small amount "suspended" in it without a reaction taking place.

I have looked into which plastics are best compatible with sulfuric acid (HDPE and PTFE) but was unable to find any information about "sponge-like" forms of these plastics.


texts: Does reaction quotient Q take into account pure solids and liquids?

texts:
I understand that the equilibrium constant does not take into account the concentrations/ pressures of pure solids and liquids. How about the reaction quotient?

In the following reversible reaction, am I right to say that since water is a pure liquid, it is not reflected in the reaction quotient, hence removing water (without changing the temperature) will not shift the equation left/right after applying Le Chatelier's Principle?

$$\ce{H3PO4 (aq) + H2O <=> H3O+ (aq) + H2PO4- (aq)}$$


texts: I'm reading about electrodeposition of conductive polymers in a chemistry textbook, and the author mentions 'trace-crossing' in the 'potentiodynamic response'. From the context I can figure out that 'potentiodynamic response' means cyclic voltammogram.  But what is the 'trace crossing'?


texts: Why will A atoms diffuse from β phase to α phase and B atoms from α phase to β phase?

texts:
At the initial compositions 1 and 2 of $α$ and $β$ respectively the chemical potentials of A and B atoms in each phase can be found by extrapolation of the tangents to the free energy curves at 1 and 2 to the corresponding sides of the free energy diagram, as shown above.
All atoms diffuse so as to reduce their chemical potential.
Therefore, A atoms will have a tendency to diffuse from $α$ to $β$ $(μ_\ce{A}^α > μ_\ce{A}^β)$ and B atoms will have a tendency to diffuse from $β$ to $α$ $(μ_\ce{B}^β > μ_\ce{B}^α)$

The point marked 1 and 2 are basically the compositions of two metal alloys that have been welded. Now annealing is performed at a particular temperature $T_1$ to bring about the change now why will A atoms diffuse from $\beta$ phase to $\alpha$ phase and B atoms from $\alpha$ phase to $\beta$ phase?
How will drawing a common tangent be different in interpretation than drawing two individual tangents at compositions 1 and 2?


texts: What are some easily-undertaken reactions that will precipitate or restore the iron from rust, in a non-lab context?

texts:
Unusually, this question arises in a DIY context rather than a chemistry one.

I'm doing some work in my garden with reinforced concrete (a retaining wall against a  high bank of soil). As some will know, it usually doesn't matter if the steel used in reinforced concrete  gets rusty, because it will still have its inner bulk of steel for strength, still be gripped when concrete pours around it, and won't corrode further provided it is deep enough inside the body of concrete.

There's one exception. If the steel is used to join two sections of concrete below ground level that are poured separately, without a "water stopper", water will inevitably enter the point where the two sections of concrete meet, and in favourable conditions can slowly corrode the steel there. It's a low risk, and a long term issue, but can happen.

That's the situation I'm in, and I didn't realise the issue early enough to take precautions. Having already poured one section with its steel last year, I'm trying to retrospectively prevent possible issues before pouring the second part.

To counter any corrosion issues, I plan to use a zinc based galvanising coat to retrospectively protect the steel in the region of the join between the two lots of concrete. But there's a problem. Galvanisation relies on electrical conductivity to create the sacrificial aspect, and rust doesn't conduct. Physically stripping rust back to steel is also hard on these bars, as they are designed with an irregular surface, to enhance grip.

So I'm wondering if there is a solution via chemistry - some easily accessible way to revert a rust coat back to metallic form, or remove rust to expose metal. Most rust removal products as far as I suspect, attempt to passivate or stabilise rust, not actually return a surface to metallic conductive form.

Is there anything I can easily do to return the rust layer to an electrically conductive/metallic layer? If not, any ideas how else I might chemically reduce the scope for future corrosion over the years?

Update: noting for clarity, the join is below groundwater level, with some degree of hydrostatic pressure behind it (it's a 1m retaining wall where a soil slope in the garden was cut away, and I can't add drainage below the joint because the bottom slab is already set and the joint will be 30cm below ground level even on the lower side, hence below groundwater level). Also the concrete mix is self-consolidating/self-compacting (SCC) so air bubbles as mentioned in one answer are not an issue - both mixes are luckily, specifically designed to preclude them, and the formulation sets pre-compacted without vibrating.


texts:
Usually, in the context of non-equilibrium thermodynamics, it is said that entropy achieves a maximum in equilibrium, so the Taylor series expansion of entropy around the equilibrium state as a function of fluctuations $\xi_i$ of internal extensive variables does not have degree 1 (linear) terms, just the contributions of the Hessian matrix (which is symmetric negative definite).
\begin{align*}
S\left(\boldsymbol{\xi}\right) &\approx S\left(\mathbf{0}\right) + \boldsymbol{\xi}^{\top} \nabla S\left(\mathbf{0}\right) + \frac{1}{2 \, !} \boldsymbol{\xi}^{\top} \mathbf{H} \left(S\left(\mathbf{0}\right)\right) \boldsymbol{\xi} \\
&= S_0 + \frac{1}{2} \boldsymbol{\xi}^{\top} \mathbf{H} \left(S\left(\mathbf{0}\right)\right) \boldsymbol{\xi}
\end{align*}
This is necessary to derive Onsager relations. But isn't there a flaw in this reasoning applied to open and closed systems? The entropy of the system should achieve max value in equilibrium only in isolated systems, shouldn't it?


texts: How many cis-trans isomers does 1-O-stearoyl-2-O-arachidonyl-phosphatidyl-inositol-4',5'-bisphosphate have?

texts:
I saw an exam that had a question asking the number of cis-trans-isomers of 1-O-stearoyl-2-O-arakidonyl-phosphatidyl-inositol-4',5'-bisphosphate:

The "correct" answer in the exam is 1023, but this is clearly not correct, because the stereoisomerism of the inositol ring is not called cis-trans-isomerism.

So, obviously only the arachidonyl chain has cis-trans isomerism. But if an isomer has several of the double bonds in trans orientation (not just one), is is still correct to call it a cis-trans isomer of the original molecule. If it is, I would say that this molecule has 15 cis-trans isomers. If it isn't I would say that it has only 4 cis-trans isomers.

Which one is correct?


texts:
You have a regular balloon, and you decide to heat it up. The gas particles inside the balloon will gain kinetic energy, and so, the gaseous particles will collide with the internal wall of the balloon with a higher frequency and more energy. This is what we call pressure, which will, as a result, increase. This is more commonly generalised to be Gay-Lussac's law, which formally states that the pressure of a gas is directly proportional to its absolute temperature.

Now, as pressure has increased, meaning that the gaseous particles are colliding with the internal wall of the balloon with a higher frequency and more energy, the balloon will begin to inflate, or in other words, the volume of the balloon will increase.

This seems to contradict Boyle's law, which states that the pressure of a gas is inversely proportional to its volume. In the scenario I described above, it seems clear to me that it was the increase in frequency of the gaseous particles colliding with the internal wall of the balloon, that too with more energy, which altogether is known as an increase in pressure, that caused the balloon to inflate.

I perfectly understand Boyle's law when the idea of a pump is used, where you can use a slider to change the volume of a gas and clearly see its inversely proportional relationship with the pressure of the gas, however, can't seem to understand what is incorrect in my logic, from which I seemingly have contradicted Boyle's law.

I am a high-school student who just learnt about these laws, and out of curiosity decided to ask this question in hopes of clearing my doubts and fundamentally gaining a better understanding. Any help will be greatly appreciated, thanks in advance.


texts:
I want to understand what is the exact mechanism by which "enediols"  reduce cupric to cuprous of  Benedict's reagent.

  The principle of Benedict's test is that when reducing sugars are heated in the presence of an alkali they are converted to powerful reducing species known as enediols. Enediols reduce the cupric compounds (Cu2+) present in the Benedict's reagent to cuprous compounds (Cu+) which are precipitated as insoluble red copper(I) oxide(Cu2O).
  [source]

Any reference would be helpful too.


texts: Does β-hydride elimination in main group metals occur?

texts:
As a side reaction of Grignard reagents, the following reaction is introduced on the Internet.
I think this is β-hydride elimination reaction, but magnesium is a main group metal, not a transition metal.
Does β-hydride elimination reaction in main group metals occur?


texts: Why is LDL more easily oxidized/damaged than HDL?

texts:
Why is LDL more easily oxidized than HDL is? By LDL and HDL, I mean the lipoproteins that carry cholesterol.

Oxidation of LDL ultimately contributes to heart disease.


texts:
Given an organic compound, is there any way to decide if it is volatile (or compare volatility--everything is volatile in the end)?

Volatility is due to the tendency to evaporate. The conclusion I can draw from this is that a more volatile compound will be lighter and/or will have less intermolecular forces. But this doesn't seem to work--I recall that methanol is less volatile than ethanol ([citation needed]).

So are there any general guidelines for this or is it another experimental property?


texts: Does an electronegative atom which carries a negative formal charge withdraw electrons by induction?

texts: Electronegative atoms withdraw electrons by their inductuve effect. Does this fact remain true even when they are heavily loaded with electrons through negative formal charge? Are these two ideas related?


texts: How can I calculate the equilibrium constant for this reaction?

texts:
Silver(II) oxide partially decomposes into solid silver and oxygen gas according to:
$$\ce{2 AgO(s) <=> 4 Ag(s) + O2(g)}$$
with enthalpy $H^\circ = \pu{62.0 kJ}$ and entropy $S^\circ = \pu{133.6 J K-1}.$
a) Calculate the change in standard Gibbs free energy. (Answer: $\pu{22.2 kJ}$)
b) Calculate the equilibrium constant for this reaction.

This is one of the exam questions I got, but I don't understand how I'm supposed to answer question b without the concentration. I also didn't get a mass or volume so I can't calculate it using the molar mass.
I tried using the formula $G^\circ=-RT \ln K,$ but I don't get the right answer with this formula. Could someone help me find the right way and formula to answer this question?
$$\frac{ΔG^\circ}{-RT} = \frac{-RT}{-RT}\ln K$$
$$\ln K = \frac{ΔG^\circ}{-RT}$$
$$
\begin{align}
K &= e^{-ΔG^\circ/(RT)} \\
  &= e^{-22.2/(8.3145\cdot 298)}\\
  &= \pu{8.18545e-9}
\end{align}
$$
The answer I'm supposed to get is $\pu{1.30e-4}.$ The answer I get according to my calculations is $\pu{8.1854e-9}.$


texts:
I am electrolysing water using several different potential catalysts for my eight grade science fair project. The electrolysis will be running at 2 to 2.5
volts over nickel electrodes, as I do not need a long term solution. How much amperage should I put on my DC power supply? Thanks and I would appreciate simplified answer compared to what you would normally give. Yes, I do understand ohms law.

Edit: I did some calculation and if I assume the resistance of the electrolyte is lets say 5 ohms, then we can assume a current of 0.5A at 2.5 volts. Is this correct?


texts:
According to the Khan Academy, the amino functional group is basic because it can remove $\ce{H+}$ from systems. Why is that?

Amino: Charged (forms $\ce{R-NH3+})$ at the pH of most biological systems. Since amino groups can remove $\ce{H+}$ from solution, they are considered basic.

My current understanding:

The $\ce{H+}$ atoms bond in a polar covalent way with $\ce{N-}$. So that means the amino acid does not release that many $\ce{H+}$ ions. I can see why this is not acidic.
$\ce{N-}$ also takes electrons from $\ce{R}$, which makes $\ce{R}$ become $\ce{R+}$. This should repel $\ce{H+}$ from elsewhere in solutions.

How does this functional group remove $\ce{H+}$ from its solutions?


texts: Reaction of substituted furan with methyl vinyl ketone with subsequent rearomatisation

texts:
I am supposed to provide a mechanism for the above transformation. I observed that the order of substituents on the product is same as that on furan, and since furan undergoes Diels–Alder reactions, I came up with the following mechanism:

Is my Diels–Alder product correct? After this, however, I have no idea how aromaticity is restored.


texts:
It is well-known that there exists the $\ce{He2^2+}$ dication, and also $\ce{HHe+}$ and $\ce{H2+}$ cations. But I could not find any definite information about the existence or inexistence of the $\ce{HHe^2+}$ cation.

It would be isoelectronic to $\ce{H2+}$, but would have a weaker bonding due to greater helium nucleus charge. It looks unlikely to be stable, but did anyone prove it by calculation or experiment?


texts: Why is the curve of an isothermal process above the that of a adiabatic process during compression?

texts:
For an adiabatic process $pV^{\gamma}=k$ and after differentiating the equation we get that the slope of an adiabatic process is $$\frac{\mathrm dp}{\mathrm dV}=-{\gamma}\frac{\mathrm p}V$$
For an isothermal process $pV=k$ and after differentiating the equation we get that the slope of an isothermal process is $$\frac{\mathrm dp}{\mathrm dV}=-\frac pV$$
It says in my book that during compression adiabatic curve is above the isothermal curve and that during expansion the vice versa happens. My question is that since the slope of the adiabatic process is $\gamma$ times more than the slope of the isothermal process, shouldn't the curve of the former process always be above the latter.


texts: Derivation of the form of the time correlation function in NMR spectroscopy

texts:
For a given protein, I know that the NMR spectrometer magnet generates a field $B_0$ and that the interactions with the spins in the local environment generates a much smaller field $B_\mathrm{loc}$ (not necessary aligned with $B_0$).

Owing to Brownian collisions between solvent molecules and the protein, the atoms associated with these spins move, hence making $B_\mathrm{loc}$ a function of time ($B_0$ is constant).

We define a time correlation function$$G(t,\tau) = \overline{B_\mathrm{loc}(t)B_\mathrm{loc}(t+\tau)},$$ where $G(t,\tau)$ is a stationary random function (see Time evolution of correlation functions (specifically Onsager's hypothesis) in time correlation link)
Hence $G(t,\tau)$ only depends on $\tau$, the delay in measuring $B_\mathrm{loc}$.

So, for simplicity we set $t = 0$ and note that

$$G(t,\tau) = \overline{B_\mathrm{loc}(0)^2} \mathrm{e}^{-\tau/\tau_\mathrm{c}},$$

where $\tau_\mathrm{c}$ is the correlation time, the time it takes for the whole molecule to rotate by 1 radian in a process called rotational diffusion.

How do I derive the second equation from the first?


texts: Why is molybdenum that important in inorganic synthesis as well as biosynthesis of ammonia?

texts: We know that Mo (Molybdenum ) is used as  a catalyst for Haber's process, during synthesis of Ammonia from Nitrogen. Again, in biological systems, Nitrogen fixation (ALSO forming Ammonia from Nitrogen) uses Mo as activator of Nitrogenase enzyme. My question is "why Mo is so special for Nitrogen?"


texts: Comparison: Esterification with acyl chloride and alcohol vs Fischer esterification

texts:
I would like to know if there are more than mentioned pros and cons with the different methods in making an ester, and also ways to maximize product yield (comparing the two).
Fischer- Pros: cheap, easy, non-toxic (or less at least) to environment/laborants. Cons: worse yield and also slow
Acyl chloride- Pros: Faster, more yield. Cons: More dangerous, harder, and more expensive.
A way to maximize yield for Fisher esterification is to increase concentration to any reactants, alternative to remove the forming water.
I have not really found how I can maximize it for the acyl chloride-method however.


texts: Is flow battery cycle life really as high as the literature claims?

texts:
I've seen a few reviews/journal articles now which claim that flow battery cycle life reaches the 10,000 mark and beyond with good capacity retention. However all of the primary sources I've came across only conduct tests for tens or hundreds of cycles, and there is almost always a significant capacity drop.

The general claim is that RFBs have a much better cyclability than solid state batteries such as lithium due to there being no physical change at the electrode, but I can't find any sources to back that up.

Can anyone show me a primary source which tests flow batteries (Preferably vanadium of iron chrome) for extended periods?


texts: What metabolite intermediate will accumulate in a mammalian cell-free extracts capable of glycolysis if lactate dehydrogenase is inhibited?

texts:
I know the reaction proceeds as follows:

Pyruvate accepts the electrons from NADH to form lactate. What would be the intermediate in this reaction? Would it be NADH or NAD+?


texts: I am working on a project wherein I am studying various properties of human hair and its utilization..I would like to know method by which we can extract melanin from human hair. Can anyone suggest some cost effective method?


texts: Does an aryl compound with any functional group attached to it, undergo benzylic oxidation?

texts:
>

If you look at this compound, only the benzylic carbon on the top has a hydrogen attached to it, so how do we oxidize only the top part without touching the lower one (not sure if this product is right), and what happens to the $\ce{-CH2}$ in the middle?

Also, does benzylic oxidation with $\ce{KMnO4}$ happen only with alkyl chains (R)? What if it had a carbonyl instead (a ketone let's say) or any other organic functional group attached to a benzene ring, what would happen to it? For example, Molecule Y here:

Why did it get oxidized to phthalic acid if the lower benzylic carbon doesn't have any hydrogen atoms attached to it?


texts: I know that analytic forms of the Helium wavefunctions are not known.  However, are there empirical expressions for the low-lying states of Helium?  I'd like to use them to calculate some transition matrix elements for fun.


texts: Specifically, if a piece of aluminized glass is heated to the melting point of the glass will the coating dissolve into it or otherwise react with it?


texts: I've read that nonpolar bonds are stronger than polar bonds. If it is true, why $\ce{C-H}$ bond entalpy ($\pu{413 kJ/mol}$) is more than $\ce{C-C}$ ($\pu{348 kJ/mol}$)? I'm very confused at the moment.


texts: What is molecular system in general terms? What is a supramolecular system?

texts:
What is a molecular system in general terms?

Could the solution of sugar in water be called a molecular system, if we were not interested in sugar-water interaction?

Today Jean Marie Lehn told me that bulk water is classical supramolecular system, but I cannot understand why.


texts: How to properly work with potassium HMDS

texts: What is the proper procedure for working with KHMDS?  I would like to use it to deprotonate a compound and have a bottle of KHMDS in toluene.  Does it need to be handled under inert atmosphere?  And is it soluble in halogenated solvents?


texts: Significance of sign of standard reduction potential

texts:
I am very confused with the signs of standard reduction potentials.
For example the standard reduction potential of Zinc is −0.76 V and that of copper is +0.34 V.

I cannot understand the  significance of the signs.

As far as I know,if the value is negative then the reaction is non-spontaneous(from the relation between Gibbs Free Energy change and Electrode potential).But if the reaction is non-spontaneous, then why are we classifying it as an electrochemical cell?

Should'nt it be classified as an electrolytic cell?
(Sorry if that sounded incorrect but my basics are weak)


texts: Thermometer fluid is separated, defective?

texts:
I bought a thermometer from Cole-Parmer having kerosene as the fluid, and the fluid is broken up. The fluid in the bottom part goes up to about 10 °C even though it is 20 °C in the room, then there is a gap followed by fluid between 23 °C and 25 °C, then there is no fluid going all the way to the top where there is another small stretch of fluid. There is a short black rubber sleeve on the top of thermometer.

Does this mean the thermometer is defective or am I using it incorrectly, not “calibrating” it or something?


texts: Identify products of Propiophenone using nmr

texts:
I've been analyzing a compound "propiophenone", using NMR and IR, and
I can't tell which of the nmr spectrums relates to which isomer of C9H10O2 is which.

At first I thought the two isomers were ethyl benzoate and phenyl propanoate, which would make the 1.5 peak from the CH3 group and the 2.7 and 4.2 peaks from the CH2, and the CO stretch in ethyl benzoate is about 1730. But then I didn't know why the stretch in the other isomer would be 1770 and I thought that the ethyl benzoatate would be the major isomer, but I was told that the isomer D (with a stretch at 1730) is the minor isomer.


texts: How to calculate the ratio of rate constants of competing reactions?

texts:
There are two compounds $\ce{A}$ and $\ce{B}$ that react with one common reagent $\ce{C}$ following first order kinetics.
  Suppose 99.9% of $\ce{A}$ must react before 0.1% of $\ce{B}$ has reacted then what is the minimum ratio of their respective rate constants?

My Attempt at the question:

We know that the reactions follow first order kinetics, hence I tried to find the time at which the given percentage of $\ce{A}$ and $\ce{B}$ is left using the formula
$$ t = \frac{2.303}{k} \cdot \log\left(\frac{C_0}{C_1}\right)$$
where $t$ is the time, $k$ is the rate constant for each reaction and $C_0$ and $C_1$ are initial and final concentration respectively.

After this I tried to find the ratio of rate constants directly but couldn't arrive at the answer.
I derived the above formula using the integrated rate law.


texts: Which reaction between Lugol and Hydrogen peroxide?

texts:
The Lugol solution is a mixture of $\ce{(K+, I- )}$ and $\ce{I2}$ such that $\ce{I3-}$ are formed by:

$$\ce{I- + I2 -> I3-}$$

I know that the brown color comes from $\ce{I2}$, but in this solution one have $\ce{I3-}$ not $\ce{I2}$, why is it brown?

When I mix Lugol with $\ce{H2O2}$ without the presence of $\ce{H3O+}$ there is a variation in the conductivity of the mixture but the brown color doesn't disappear. If I add $\ce{H3O+}$ the solution becomes transparent after few minutes.

My guess is that either $\ce{I2}$ is reduced by $\ce{H2O2}$ (hence the disappearing of the brown color) or a redox reaction between $\ce{H2O2}$ and $\ce{I-}$, but in the later case I don't understant why the brown color disapear instead of appearing.

Can you enlighten me please, thanks.


texts:
I was wondering whether the following order (from here) is correct:

In the first inequality, why did 9 hyperconjugations dominated resonance effect of benzene ring?
In the last inequality doesn't the 2 hyperconjugations of vinylic carbocation overpower the methyl carbocation?

In middle there is:
allyl = secondary

Why is there an equality here when resonance dominates inductive effect?


texts: How to determine the molecular formula of a compound given its molecular mass and mass percentage contribution of the involved elements?

texts:
Hydralazine is a drug used to treat heart disease. It is $59.99\%$ carbon, $5.03\%$ hydrogen, and $34.98\%$ nitrogen and has a molecular mass of $160.178$.

What is the molecular formula for hydralazine?

I did:
\begin{align}
59.99~\ce{C}/12.011&=4.994\\
5.03~\ce{H}/1.01&=4.9801\\
34.98~\ce{N}/14.007&=2.4973.
\end{align}

Then divided all $3$ by $2.4973$, and got 2 carbon, 2 hydrogen, and 1 nitrogen atoms i.e. $\ce{C_2H_2N}$. The online homework said that the stoichiometry was wrong. I don't know what I did wrong.


texts: Could coating silver inside of a cuvette be used for SERS?

texts:
I understand that molecules adsorbed to a coinage metal surface experience plasmonic enhanced Raman shifts and I have a spectrometer that I would like to perform SERS measurements with but do not have a Raman microscope/probe. I do have a light-tight cuvette cell and I am wondering if I could coat the inside of a cuvette on two sides with silver to obtain SERS spectra of liquids? This is a standard 1x1 cm cuvette and the SMA cable going to the spectrometer has a long pass filter installed for the correct wavelength.

Most of the literature I have read points to using a suspension of silver nanoparticle colloids mixed with the analyte liquid within the cuvette to obtain SERS spectra, but I have not been able to find any papers that use what I am proposing.


texts: Balancing a reaction with unknown products

texts:
I'm given this equation in word form:

$$\ce{sodium (s) + water (aq) -> unknown~products (s/g/aq)}$$

and I have to convert this to a chemical equation. I understand how to covert this normally, that equation can hence be represented by:

$$\ce{Na + H2O -> unknown~products\:(s/g/aq)}$$

This is indeed a single displacement reaction so it should become (according to what I know so far) $\ce{Na2O + H2}$ but after doing some research, I got that it should be:

$$\ce{Na + H2O -> NaOH + \frac{1}{2}H2}$$ or $$\ce{2Na + 2H2O -> 2NaOH + H2}$$

I'm lost now, where did $\ce{NaOH}$ come from? Especially the H since there is no reason for hydrogen to be present.

Please explain why and how to balance this reaction or convert this and what factors to look at when dealing with these types of equations.


texts: Can anyone suggest a mechanism for hemiaminal metal complex to imine complex?

texts:
Can anyone suggest a probable reason for this conversion? This seems like a simple conversion from hemiaminal to imine.
For secondary amine this kind of conversion might be possible by

but in the case of tertiary amine how can something like this form? Is there a chance of removal of RCH2OH?
The metal here is copper(II). Is it possible that the metal has some role to play?


texts: Calculating phosphorescence quantum yield using the given datas'

texts:
A molecular excited state has a fluorescence lifetime of 10 nanoseconds and a phosphorescence life time of 10 microseconds. There are no other processes, what's the phosphorescence quantum yield?

I divided the above two lifetimes naively to get $0.1\%$.  I believe we can use the equation $\phi_f = k_r \times \tau_f$, and similarly for $\phi_p$, then divide the two. But I am not sure at all. Can anyone guide me how should I solve this question and is my answer correct?


texts: Role of calcium oxide in soda lime decarboxylation

texts:
Why do we use calcium oxide $\ce{CaO}$ in soda lime decarboxylation?
$$\ce{\underset{sodium acetate}{CH3COONa} + \underset{sodium hydroxide}{NaOH} ->[\Delta][CaO] \underset{methane}{CH4} + \underset{sodium carbonate}{Na2CO3}}$$
It seems as if it is dehydrating agent to keep NaOH dry), but why is the dehydrating agent required if the heat would be enough to dehydrate the container as the temperature is very high (expected to be over 100 °C)?


texts:
Apologies for this extremely basic question, I'm just beginning with Chemistry so please don't be too harsh on me.

My book says that sulfuric acid, $\ce{H2SO4}$, dissociates in its ions following this reaction: $$\ce{H2SO4 -> H2^+ + SO4^{2-}}$$

My question is, why can't the dissociation reaction happen like this:
$$\ce{H2SO4 -> 2H^+ +SO4^{2-}}$$

I know hydrogen is a diatomic gas, but here I don't know if H will dissociate as a gas or as a liquid (since $\ce{H2SO4}$ is a liquid, not a gas).

I'm trying to learn, thank you for your understanding and your time.


texts: Can a free radical be created by chemical reaction of non-radical species?

texts:
Here's my thinking:

Atomic oxygen in its ground state is a free radical because there are two unpaired electrons in p-orbitals.
When species react new orbitals are formed, and perhaps a situation can occur where the amount of degenerate orbitals is changed by a chemical reaction. This would implicate the filling of these orbitals, following the aufbau principle and hunds rule of filling.
Therefore it is thinkable that two reactant species (i.e. not homolytic bond fission) which are not radicals, can react in such a way that the new electron orbitals are filled in such a way that all electrons are no longer paired => radical species formed from non-radical species.
Likewise it is conceivable that a radical species can react with a non-radical species (i.e. not an even number of radical species terminating eachother) to form only non-radical species.

Is my argument and results 3 & 4 correct? Can someone give an example of 3 and/or 4?

Edit: My main takeaway - when considering the feasibility of a radical creation/destruction, look at conservation of spin


texts: Reduction of glucose to hexane with hydroiodic acid

texts:
My book (NCERT India) states that n-hexane is formed when glucose is heated in the presence of hydrogen iodide. That is, the following reaction takes place:
$$\ce{C6H12O6 + HI ->[{\Delta}] C6H14}$$
This seems a bit strange to me because I only know of three possibilities that can occur when a compound containing hydroxyl groups is treated with a strong acid:

A substitution reaction, where all the $\ce{-OH}$ groups are replaced by $\ce{-I}$
A dehydration reaction, where $\ce{H2O}$ molecules would be eliminated and it would end up with few double bonds.
Formation of an ether.

There are also other sources which mention this reaction (thanks to Karan Singh, Tyberius, and user55119 for pointing these out). A Michigan State University webpage states that:

  Hot hydriodic acid (HI) was often used to reductively remove oxygen functional groups from a molecule, and in the case of glucose this treatment gave hexane (in low yield).

Also, Dietary Sugars (edited by Preedy, V. R.) states (p 80) that

  Glucose is reduced with concentrated hydriodic acid in the presence of red phosphorus to form a trace amount of n-hexane. This indicates an unbranched chain of six carbon atoms [...]

It goes on to cite the 5th edition of Principles of Biochemistry by Nelson et al. (published 2008), but I could not find this statement in any recent edition of this book.

Lastly, a similar reaction was carried out by Kiliani (Ber. Dtsch. Chem. Ges. 1885, 18 (2), 3066–3072) where the cyanohydrin of fructose was reduced to to 2-methylhexanoic acid using hot HI and phosphorus.

I would like to know:

Is phosphorus required for this reaction, or not?
What is the mechanism by which this reaction proceeds, with or without phosphorus?


texts: Calculation of an equilibrium reaction quotient

texts:
For the equilibrium

  $$\ce{2 SO2(g) + O2(g) <=>  2 SO3(g)}$$

  $$K_c = 245\ (\text{at}\ 1000\ \mathrm K)$$

  The equilibrium concentrations are $[\ce{SO2}] = 0.102$, $[\ce{O2}] = 0.0132$, and $[\ce{SO3}] = 0.148$. Suppose that the concentration of $\ce{SO2}$ suddenly doubled. Calculate the $Q$ and use it to show that the forward reaction would take place to reach a new equilibrium.

I created an ice table so then I was able to find $x$:

$245=(0.148+2x)^2$ divided by $(0.0132-x)(0.204-2x)^2$

$x=0.01$

So the equilibrium concentrations are: $0.184$ for $\ce{SO2}$, $3.2\times10^{-3}$ for $\ce{O2}$ and $0.168$ for $\ce{SO3}$.
To check if the forward reaction is favored, $q<k$. The answer key states that $q=61.6$ but I don't know how they got it.


texts: Comparison of ways to provide energy to a reaction

texts:
As we all know, you can provide energy to a reaction to overcome the activation energy of a reaction by heating the reaction.

I have, however, recently sat through a talk where someone 'powered' a reaction through ultrasonic waves. Apologies, but it was a rather small symposium, so I don't have the details readily available to me to illustrate it.

This was very interesting to me. I'd love to be able to just put my mixture in a ultrasonic bath and not have to fool with heating (Or at least have an educated option of trying it).

There's a fairly large field of photochemistry that I believe is based around this same principal, and I have a general understanding of the concept.

However, how would one go about exploring alternate pathways to replace heating a reaction? I think I grasp the concept theoretically, I just do not understand the origins of it or how to apply it to a new situation.


texts: Reversibility of an acid's reaction with water depending on its strength

texts:
This is how my chemistry professor compared reaction of a weak and a strong acid with water:

  $$\ce{HCl + H2O -> H3O+ + Cl- + Heat}$$
  In this case $\ce{H2O}$ breaks the bond between $\ce{H}$ and $\ce{Cl}$ in $\ce{HCl}$ which results in he formation of $\ce{H+}$ and $\ce{Cl-}$ ions. The $\ce{H+}$ ion combines with $\ce{H2O}$ to form $\ce{H3O+}$ (also known as hydronium). Since adding water to an acid causes its hydration, which is an exothermic process, the reaction also results in the emission of heat. This reaction favors going to the right hand side of the equation.
  $$\ce{CH3COOH + H2O <=> H3O+ + CH3COO- + Heat}$$
  In this case, the size of the acid is greater than the size of $\ce{HCl}$. It means that the process of hydration will be slower. This will lead to a comparatively less number of $\ce{H+}$ ions being combined with water. So, considering Arrhenius' definition of acids, $\ce{CH3COOH}$ is a weaker acid than $\ce{HCl}$. Also, this reaction is going to be reversible.

Now, my questions are as follows:

Why the first reaction favors going to the right hand side of the equation? I think that it has something to do with heat as the heat is lost to the surroundings and the energy level on right hand side decreases. I am still not sure.
Why is the second reaction reversible? I have no idea of why it is reversible so I can't provide my opinions.
Why does water causes ionization of acids? This question might look dumb to some but I am wondering what special water has got that it ionizes acids (or maybe other species too).
Why is there a release of heat? I have read that breaking of bonds is an endothermic process.


texts: Why do selenium , tellurium and polonium have more negative electron gain enthalpy than oxygen?

texts:
In my book(NCERT Chemistry Part I, Textbook for Class XI[1]) a list of values of electron gain enthalpies of various elements is given. According to that list, oxygen has less negative electron gain enthalpy than selenium, tellurium and polonium. Shouldn't it be the opposite because electron gain enthalpy becomes less negative down a group?

Reference:
[1]: Rajput, Anup, Kumar. Classification of Elements and Periodicity in Properties. NCERT Chemistry Part I, Textbook for Class XI, First Edition(October 2019 Reprint); Uppal, Shveta, Banerjee, Binoy, Eds.; National Council of Educational Research and Training: New Delhi, India, 2006; pp 90.


texts: Why doesn't a table sublimate, while ice does?

texts: A table does not sublimate, and nor does a spoon. Ice does, however. What is the fundamental difference?


texts: Do dyed-alcohol thermometers tolerate cold/hot stems?

texts:
How do the red organic solvent thermometers respond to having the tip submerged while the stem is at a different temperature? I understand mercury thermometers could easily handle this, and bimetallic strip probe thermometers fail utterly.

To put it simply, if I'm heating just 2-3 cm of liquid, can an organic solvent thermometer still give accurate readings?


texts: Quick way to find magnetic nature of compounds or ions

texts: According to the Molecular Orbital Theory, the method to check whether a given compound is paramagnetic or diamagnetic is to draw the molecular orbitals and then to see whether we have all the electrons paired or is there some unpaired electron. However, I want to know, is there a quick way to find the magnetic nature without drawing the orbital diagrams?


texts: Does something like a fluorescent foil or a fluorescent film exist?

texts:
During my experiments I want the emitted laser beams to come back with a different wavelength than the original wavelength using a fluorescent foil or fluorescent film.

The laser I'm currently using has a wavelength of 632.8 nm. The color of the emitted beams doesn't matter (it can have every color).

Therefore I want to ask if something like this is principally possible and if a fluorescent foil/ film does exist?


texts: What does $\ce{Cu}$ do? And why do we need it? Can we not do $\mathrm{S_N}2$ without it? And is there any other metal that can help in this? Maybe something like $\ce{Ag}$? I'm guessing this because the special thing about $\ce{Cu}$ is that it is worse reducing agent than $\ce{H}$.


texts: How do I figure out the composition of a material given specific densities?

texts:
The Problem
A waste material consists of sand (SG 2.7), a chemical salt (SG 2.1), and a dense plastic (SG 1.4). 200 g of a representative sample from the material is found to have a density of 2300 kg/m3. The salt is dissolved out of the sample which, after drying, now weighs 170 g. What is the composition of the waste material?
My Attempt

Based on the given information, we can derive:

densitysand = 2700 kg/m3
densitysalt = 2100 kg/m3
densityplastic = 1400 kg/m3
masssalt = 30 g = 0.03 kg
proportionsalt = 0.03 kg / 0.2 kg = 0.15

To try and calculate the individual mass of sand and plastic in the sample, I used the density = mass / volume equation to first figure out the volume using the density and mass of the total sample.

densitytotal = masstotal / volume =
volume = masstotal / densitytotal = 0.2 kg / 2300 kg/m3 = 0.00008696 m3
masssand = 2700 kg/m3 * 0.0000869 m3 = 0.2348 kg
massplastic = 1400 kg/m3 * 0.0000869 m3 = 0.1217 kg
But I don't think this step was the right choice since the mass of the sand came out to be larger than the mass of the sample. Was I correct in trying to figure out the value of the mass of sand and plastic or was that the wrong approach to determine the material's composition? If it's the first case, how should I find out the mass values?


texts:
According to several articles from the American Water Works Association, permeate from RO should be stabilized in terms of pH and hardness to avoid corrosion of the distribution piping.
How does corrosion differ from that of normal water? Would RO water corrode stainless steel faster than normal water if both had the same chloride concentration?


texts: Why fire spreads out, depending on burning substance, with different speed?

texts:
In Action movies, I have seen a couple of times that if flammable gases or liquids like benzene are ignited, the fire spreads out within fraction of a second and sometimes there is also an explosion. However, if a Piece of wood in a grill is lightened, it may take minutes if the fire has the full Magnitude. Why there is a difference in ignition Speeds (what is the physical cause)?

Are there kinetic equations how to determine the Speed how fast a fire would spread out?

I am interested in the viewpoint of thermodynamics how to derive the Speed of ignition.


texts: Pressure dependency in Haber Bosch ammonia synthesis

texts:
Haber-Bosch ammonia synthesis reaction:
 $$\ce{3H2 +N2 -> 2NH3}$$

According to the ideal gas law: $pV=nRT$ where constant volume implies $\displaystyle \frac nV=\frac p{RT}$

Then $\displaystyle K_\mathrm c=\frac{[\ce{NH3}]^{2}}{[\ce{H2}]^3\cdot [\ce{N2}]}$

When I substitute $\displaystyle \frac nV=c=\frac {p_{\text{gas}}}{RT}$ I get:

$$ K_\mathrm c=\frac{\left(\frac{p(NH_3)}{RT}\right)^2}{\left(\frac{p(H_2)}{RT}\right)^3\left(\frac{p(N_2)}{RT}\right)}=\frac{R^2T^2}{p^2}$$

But according to Le Chatelier's principle, increased pressure should result in an increased $K_\mathrm c$, but my $\displaystyle K_\mathrm c\approx \frac 1{p^2}$.

Where is the error? Is is impossible to combine the partial pressures like that because they scale differently with total pressure? Can one derive from the gas law the pressure dependency of this reaction?

Edit after solved:

First mistake was that the formula had $K_c$ (constant) instead of Q,
$$ Q=\frac{\left(\frac{p(NH_3)}{RT}\right)^2}{\left(\frac{p(H_2)}{RT}\right)^3\left(\frac{p(N_2)}{RT}\right)}=\frac{R^2T^2}{p^2}$$
where Q is the current value/ratio of concentrations, so the reaction tries to get Q back to $K_c$ so for greater pressure p, Q is smaller so the reaction goes in the direction of NH3...


texts: The effect of pressure on boiling point?

texts:
My textbook states the following:

Qualitatively, I understand why the boiling point of a substance increases when the pressure is increased. However, I learned that if the pressure is increased when the reaction system is at equilibrium, the volume of the system decreases and hence, the reaction will proceed in that direction in which the volume of the system increases. In the above scenario, however, it has been given that water in the gaseous form occupies more volume than its liquid form and so, shouldn't the given reaction proceed in the forward direction, hence reducing the boiling point?

Please note that I am convinced and I believe that it makes sense for the boiling point to increase when the pressure increases but can somebody please explain the flaw in my reasoning with regard to the given equilibrium?

Much thanks in advance :) Regards.


texts:
I learned that alkynes gets reduced on addition of $\ce{Na}$ in liquid $\ce{NH3}$ to form alkenes (which is not further reduced). Recently I came across a reaction where a conjugated diene was treated with $\ce{Na}$ in liquid $\ce{NH3}$ .The product was what you would get by 1,4 adding $\ce{H2}$ in the conjugated diene.
Is this reaction correct? If yes ,then what makes it more reactive than an ordinary alkene?


texts: How do you stop a Pharoah's Serpent reaction?

texts: I am a novelist and working on a book. I have been searching google for an answer to the above question. How does one stop a Pharoah's Serpent reaction? Thanks!


texts: Chemistry of toilet bowl mineral stains on porcelain

texts:
I live in Massachusetts, my house has 3 bathrooms and I live alone.  If I don't scrub my toilet bowls once a week they build up brownish-yellow mineral stains.  These seem independent of whether I've actually used that toilet bowl since the previous cleaning (since I live alone some toilets are seldom used).

Looking on the web there's lots of advice from "folksy" sources like "frugal blonde" or "professional mom" about how to clean toilets -  usually involving vinegar, Clorox, pumice-sponges, etc, and lots of elbow grease, rubber gloves, bathroom fans and time.   One guy uses WD-40!     But being "folksy" none of these involve any discussion of the chemistry.

I thought if I understood the science I could save work and maybe even prevent the stains but I can't find ANYTHING on the web about this!  What are the minerals in my water and what form are they in?   Are they ionized or just some sort of suspension?  What are the principal forms -  I assume calcium, magnesium (and silicate?) compounds -  and what form do they precipitate out in on the porcelain?   What IS porcelain (chemically-speaking) anyway, and what makes such tight bonds at the interface between the minerals from the water and the porcelain surface?

If I knew the answers to these maybe I could even prevent these porcelain-mineral bonds from forming


texts:
While brushing up on my Chemistry basics, I came across a topic about naming ionic compounds. It is a question regarding Roman numerals.
It says "Roman numerals should not be included in the name when the metal can only form one cation."

The cation of $\ce{Zn^{2+}}$ has +2 charge, and $\ce{NO3-}$ anion has -1 charge.

which results in having $\ce{Zn(NO3)2}$

If Roman numerals are used for transitional metals and given that zinc is part of the transitional metals, why is this ionic compound named as zinc nitrate instead of zinc(II) nitrate?

Thanks.


texts:
I'm interested in whether there are a small subset of elements that are by far the most common in a planet's early stages of formation and a wider range are formed slowly over time through chemical reaction, or if a very wide range of the periodic table can be initially found from the start.
Obviously every planet it unique, but I'm asking about whether there's a common scenario / elemental ratio present in the hot cataclysmic early stages of a planet's formation, or rather it's pretty much diverse from the start. Do most elements generally exist in a planet during early formation, or is it a small subset?


texts: Is There an Acceptable Potential Which Can Represent the Interaction between Finite-sized Ions?

texts:
The question is as mentioned in the title. Take for example the interaction between $\ce{Ar^+}$ and $\ce{Ar^+}$. In general, is there an acceptable potential which can represent the interaction between $\ce{X^{m+}}$ and $\ce{X^{n+}}$, where $\ce{X}$ is a given element and $m,n=0, \cdots, Z$, where $Z$ is the atomic number of the element $\ce{X}$?

In many cases the coulomb potential (e.g. $V(r) = 1/r$) suffices. However, when density increases (e.g. at liquid/solid density), the size of the positive ion might become relevant.


texts: Pseudoelementary reactions in the Briggs-Rauscher oscillatory reaction mechanism

texts:
In this paper on the Briggs-Rauscher mechanism (JACS, 1982, paywalled), Noyes and Furrow propose an explanation of the oscillatory behaviour of the reaction based off of about eleven reactions from a selection of processes they consider "might contribute". The authors, however, call these processes "pseudoelementary reactions" and some of them, such as
\begin{equation*}
\ce{IO3- + HIO2 + 2H+ <=> 2IO2 + H2O}
\end{equation*}
seem to involve the collision of four molecules at the same time, which I was always taught is not very plausible. Many of these reactions are trimolecular, like
\begin{equation*}
\ce{HIO2 + I- + H+ -> 2HIO}
\end{equation*}
which I also find strange (these two reactions that I picked out are specifically reactions they say postulate that are important for the oscillatory behaviour).

I had never come across such a thing and I am nor really sure what to make of this. Are these reactions not actually elementary? What do they mean when they say the reactions are pseudoelementary? Are reactions involving the collision of four or three molecules more common than I thought? When they write down the equations for these reactions they write them as if the stoichiometric coefficients were the order with respect to each reagent, which seems to imply that the reactions are somehow elementary, which further confuses me. For instance, for the first reaction (which they call I3 in the paper) they explicitly write
\begin{equation*}
\frac{\mathrm{d}[\ce{HIO2}]}{\mathrm{d}t} = k_{I3} [\ce{H+}]^2 [\ce{IO3-}][\ce{I-}]
\end{equation*}


texts:
I'm not sure if this is an appropriate question for Chemistry.SE, but I'm taking a stab. I'm running ab initio MD calculations in VASP and I'm trying to optimize different input tags. On the VASP website, it says that the MAXMIX tag should be set to at least 3 times as large as the number of electronic iterations required to converge the first step. I tried doing this, but I didn't see any speed up and instead a significant slow down. I'm wondering if anyone else has encountered this issue.

The system that I'm simulating is a silicon supercell in contact with water.


texts:
So I am very confused as to the calculations behind this. I am given a chart of data as followed:enter image description here
So based on this chart, I had to calculate:

The heat capacity of the calorimeter on benzoic acid combustion.
Make a balanced equation and the experimental value of enthalpy of combustion for both compounds (in kJ/mole)
Find the enthalpy of formation for both compounds using the values found for the enthalpy of combustion, the balanced combustion reaction, and the enthalpy of formation of water(-285.5) and carbon dioxide(-393.5)
Find the internal energy of combustion for both compounds (in units kJ/mole and J/g).


texts: Is Kirchoffs law valid at all pressures?

texts:
$$\Large H_{T_\mathrm{f}, p}=H_{T_\mathrm{i},p}+\int_{T_\mathrm{f}}^{T_\mathrm{i}}c_p(T)dT$$
This can be derived by integrating: $$C_v =\left(\frac{\mathrm{d}U}{\mathrm{d}T}\right)_V$$
Applying this to both reactants and products in a reaction, and subtracting reactans from products, we can arrive to

$$\Delta H_{T_\mathrm{f},p}=\Delta H_{T_\mathrm{i},p}+\int_{T_{\mathrm{f}}}^{T_{\mathrm{i}}}\Delta c_p(T)\mathrm{d}T \tag{1}\label{a}$$
Where $$c_p(T)=\sum_i\nu_\mathrm{i}c_{p,\mathrm{i}}(T)$$
This is essentially Kirchoffs law how enthalpy varies with temperature. However, whenever I see the the  equation $\ref{a}$, it always deals with standard enthalpy changes, i.e: $$\Delta H_{T_\mathrm{f}}^{⊖}=\Delta H_{T_\mathrm{i}}^{⊖}+\int_{T_{\mathrm{f}}}^{T_{\mathrm{i}}}\Delta c_{p^{⊖}}(T)\mathrm{d}T $$
 Is this law not valid for all reactions? If so, what is the mistake in the above derivation?


texts: How to rationalise the basicity order of phenylenediamine?

texts:
Why is the basicity of para- > meta- > aniline > ortho-
for phenylenediamine?
($\mathrm pK_\mathrm a$: ortho: 9.53, meta: 9.12, para: 7.96) I tried deducing it using resonance and inductive effects but got stuck.


texts: What is the nature of the Fe–O2 binding in oxymyoglobin and oxyhemoglobin?

texts:
Deoxymyoglobin ($\ce{Mb}$) is known to have iron in the +2 oxidation state; I believe this was deduced from its magnetic moment, which corresponds to four unpaired electrons in high-spin $\mathrm{d^6}$ Fe(II).

However, upon binding of $\ce{O2}$ (which is itself paramagnetic) to Mb, the resultant complex oxymyoglobin ($\ce{MbO2}$) is found to be diamagnetic.

This observation has been rationalised in several ways over the years. As far as I know, the two main camps are:

The oxygen ligand binds to low-spin Fe(II) in the form of singlet oxygen, via $\ce{O2}\rightarrow\ce{Fe}$ σ donation and $\ce{O2}\leftarrow\ce{Fe}$ π backdonation, which mirrors the binding mode of the isoelectronic $\ce{NO-}$. Neither metal nor ligand possesses unpaired electrons;
Fe(II) is oxidised to Fe(III), with reduction of $\ce{O2}$ to $\ce{O2-}$; thus both the metal and the ligand possess one unpaired electron. These two electrons interact via antiferromagnetic coupling to produce a singlet state.

The former viewpoint was championed by Linus Pauling, and the latter by Joseph Weiss, leading to a rather heated debate in Nature.1–3

These descriptions of myoglobin of course also apply to hemoglobin, where each monomer is structurally similar to myoglobin.

What experimental evidence supports either side, and is there any general consensus as to which is correct?

References

1. Weiss, J. J. Nature 1964, 202 (4927), 83–84. DOI: 10.1038/202083b0.

2. Pauling, L. Nature 1964, 203 (4941), 182–183. DOI: 10.1038/203182b0.

3. Weiss, J. J. Nature 1964, 203 (4941), 183. DOI: 10.1038/203183a0.