texts: Volume of Oxygen Produced By Electrolysis of Water

texts:
I am trying to estimate the volume of oxygen that will be produced by electrolysis of water at normal temperature and pressure with a current of $\pu{50 A}$. The following is my calculation:
The reaction is
$$\ce{2H2O -> O2 + 4H+ + 4e-}$$
Therefore, to produce $\pu{1 mol}$ of $\ce{O2}$ ($\pu{24 L}$), we need to move $\pu{4 mol}$ of electrons through the circuit and this is $4F = 4 \times 9.65 \times 10^4 = \pu{3.86 \times 10^5 C}$ of charge. With a current of $\pu{50 A}$, we move $50 \times 60 = \pu{3000 C}$ of charge per minute. Therefore, we produce $\frac{24}{3.86 \times 10^5} \times 3000 = \pu{0.186 L}$ of $\ce{O2}$ per minute.
Is this calculation correct? If it is, is there any way to improve the yield of oxygen?
Disclaimer: I am not a chemist and it has been years since I studied physical chemistry. The reason for this computation is to decide if electrolysis is a quick and feasible method to produce oxygen to help mild COVID patients at home (since there is a severe shortage of oxygen and concentrators where I live).


texts: On the molybdenum(III) oxide-catalysed oxidation of alkanes to carbonyls

texts:
The following reaction is specified in my notes;
$$\ce{CH4 ->[Mo2O3, \Delta]HCHO}$$ The intermediate steps involve the dehydration of an alcohol to yield the final product.
Wouldn't this only work if there's acid in the reaction mixture? Or is it that water functions as a proton donor, inducing the protonation of the hydroxyl and causing the dehydration?


texts: Balancing REDOX reactions in a basic solution, when no H+ ions are present

texts: I am trying to balance the following redox reaction, in basic solution. From what I have learned, to balance a redox reaction in basic solution you simply balance it as you normally would in acidic solution, then make sure the H+ ions are neutralized by adding OH- ions. In the example below, is my answer balanced in basic solution already? Or do I need to somehow cancel out the H present in H2O?


texts: Which carbons in pyrrole have the highest electron density?

texts:
In pyrrole, which carbon atoms have the greatest electron density?

In the resonance structures of pyrrole, all carbons can formally bear a negative charge, so it's not immediately obvious which one is most electron-rich:

My book claims that because resonance forms 1c and 1d are greater contributors to the resonance hybrid than 1b and 1e, the α-carbons (which bear the negative formal charge in 1c and 1d) are more electron-rich. Is this really the case?


texts: Inductively Coupled Plasma and Mass Spectrometry

texts: I was doing some homework and I was reading about how ICP is suitable for mass spectrometry and it said how its high temperature favours ionization which is good in MS. But also, because the temperature is so high in a plasma, wouldn't there be a very high collisional frequency which could cause side reactions/disruption of the signals, etc?


texts:
I would like to dissolve $\ce{CaSO4}$ in a hardened condition (e.g. gypsum board) as fast as possible. I have seen in posts about $\ce{CaSO3}$ that vinegar and sulfamic acid are able to dissolve it.

However, I would appreciate leads to reactants that are a little more active. Basically I am looking for a drop of something that would instantly create a hole.


texts:
Solid silicon dioxide has a giant lattice structure with single covalent bonds, while in the gas phase it has a molecular carbon dioxide-like structure. But what about in the liquid phase?

Would it be formed of molecules as well, or are there still only single covalent bonds that form and reform? Or is it more like metallic bonding with delocalized electrons? Or something else entirely?


texts: Carbonic Acid Titration with Sodium Hydroxide

texts: For my school lab, I'm determining the solubility of carbon dioxide at different temperatures. I will determine the amount of dissolved carbon dioxide by titrating carbonated water with sodium hydroxide. I'm confused as to how I can determine the pH at equivalence point (for indicator)? I don't know the concentration of the carbonated water so how would I go about determining the appropriate indicator?


texts:
Why do dehydrohalogenation reactions mostly follow the E2 mechanism? Doesn't the base play a role in deciding whether a particular reaction will follow E1 or E2? For eg, a strong base would favor e2 and a weak one would favor E1. In fact, if dehydrohalogenation reactions follow the E1 mech, a carbocation would be formed which can undergo rearrangement to the carbon directly attached to the halogen, and can undergo resonance with it. Why doesn't that happen?

Also, in this question, for example, E1 reaction seems to be major. Why is that so, and what conditions have to be satisfied in dehydrohalogenation reactions for them to be E1?


texts: Getting Molecular Orbital contributions to the ESP fitted charges

texts:
For a single determinant wavefunction, the electron density is the sum of the densities arising from each molecular orbital. The molecular Electrostatic potential $\phi_{mol}$ is calculated from the total density and therefore, at a given point $\vec{R}$, its value is given by the sum of all the contributions arising from each MO.
\begin{equation}
\phi_{mol}(\vec{R})=\sum_{i=1}^{N_{MO}} \phi_{i}(\vec{R})
\end{equation}
Atomic partial charges can be obtained by fitting the total molecular ESP in different flavors and with different constraints, however I am interested in knowing for a given atom $I$, the charge contribution of each molecular orbital to the total ESP-fitted charge, namely the elements in the summation below
\begin{equation}
q^{_I}=\sum_{i=1}^{N_{MO}} q_{i}^{_I}
\end{equation}
Is there anyone knowing a software for wavefunction-analysis that can do this from a wfn file or a way of getting the solution without writing a piece of code from sctratch?


texts: Single Displacement Reactions: A + AX =?

texts:
This seems like a stupid question, but how would I find the product of a single displacement reaction like the following?

$$\ce{Pb + Pb(NO3)2 -> \ ?}$$

Normally, a single displacement reaction follows the path of $\ce{A + BX -> AX + B}$. However, what will the equation look like when A and B are the same element?


texts: Oxidation of 1,4,5,8-tetrahydronaphthalene by meta-chloroperoxybenzoic acid

texts: I came across this question in Himanshu Pandey. I can't understand why the m-CPBA attacks the central pi bond and not the lateral ones. The answer given is C.


texts: What is the proton NMR spectrum of p-methoxyphenol?

texts:
I think there will be two pairs of doublets, since the hydrogens adjacent to the $\ce{OCH3}$ and those adjacent to the $\ce{OH}$ group will be in different environments. The answer, however, is that there'll be a singlet for 4 Hydrogens.

To give some context, I am extremely unused to the proton NMR of benzene derivatives, and any (introductory) links telling me a bit about it would be appreciated. I'm aware of the theory behind NMR spectrosocopy, the 'n+1' rule, and the ways to tell if two Hydrogens are magnetically equivalent.


texts: Why is the atomic radius of krypton smaller than that of potassium?

texts:
A potassium atom comprises 19 protons and 18 core electrons. Those electrons screen 18 protons worth of Coulomb force. Therefore, there is one proton worth of Coulomb force attracting the valence electron of potassium. Whereas, krypton comprises 36 protons and 28 core electrons. Its electrons screen 28 protons wroth of Coulomb force. Therefore, there are eight protons worth of Coulomb force attracting the valence electrons of krypton.

Consequently, there is more Coulomb force attracting the valence electrons of krypton than there is attracting the valence electron of potassium; accordingly, the atomic radius of krypton is smaller than the atomic radius of potassium.

Is that correct?


texts:
When concentrated sulfuric acid is added to anhydrous potassium chloride and the fumes produced are bubbled into aqueous potassium iodide solution, the observed solution would be colourless solution.

I think the first reaction is:
$$\ce{2KCl(aq) + H2SO4(aq) -> K2SO4 + 2HCl(g)}$$

I assumed the second reaction would be:
$$\ce{HCl + KI -> KCl + \frac{1}{2}I2 + \frac{1}{2}H2 }$$

However the second reaction is wrong according to the answer book as $\ce{HCl}$ won't react with $\ce{KI}$. From what I know, $\ce{Cl}$ is a stronger oxidising agent than $\ce{I}$, so shouldn't $\ce{I-}$ in $\ce{KI}$ be oxidized to $\ce{I2}$? I am an A-levels student so would appreciate a simpler answer.


texts: Which is the specific heat of human body?

texts: I'm studying about heat transfer and I wanted to know if there exists a specific heat of the human body or how one studies the human body's heat transfer.


texts: Why can phosphorus have 5 bonds while nitrogen cannot?

texts:
Phosphorus can form 5 bonds like in the case of phosphate. While nitrogen is known to make a maximum of 4 bonds (3 covalent, 1 dative covalent). But why is this so?

Is it because nitrogen doesn't have available d orbitals while phosphorus  has available d orbitals? Or does the presence of d orbitals have nothing to do with this and it's the sizes of both atoms that allows them to make more bonds?


texts: Why does Ruthenium only have one electron in its 5s orbital in the neutral oxidation state?

texts:
So recently I have undertaken some research with some organometallic chemistry involved, specifically regarding that of ruthenium-aryl compounds. Trying to understand the chemistry of the central metal ion, I noticed something weird a couple of weeks ago, from Wikipedia: Ruthenium only has one electron in that orbital ($4d^75s^1$), rather than the two one would expect a transition metal to have, going with a naive Aufbau across the periodic table.

I am aware, I think, in the 4th period period transition metals, of a tendency to promote their 4s electrons to the 3d orbitals, when possible, so that they have either "half-filled" (5 electrons) or completely filled (10 electron) shells.  These are "magic numbers" for transition metals, apparently; just another one of those heuristic things they teach you in inorganic chemistry that I wish I understood more about. But alas, ruthenium has an asymmetric 7 electrons in its 4d orbital, blasted thing.

Does anyone know anything? I tried using Google Scholar and a few databases, but when I type in "orbital" pretty much all I see is molecular orbital calculations specific to particular molecules. I'd really love to see papers pointing at some faint ideas I may be dimly aware about...


texts:
Often times Pharma molecules come as different salts where the Cation changes. Do these have typically the same or different CAS numbers?

e.g. Take Glucosamine Hydrochloride.
https://en.wikipedia.org/wiki/Glucosamine

It is available as as both the Na and K salt. But I cannot seem to find if they all have different CAS numbers.

What I have now is: 3416-24-8

Further complication seems that there is a Glucosamine Hydrochloride as well as a Sulfate. The wikipedia page describes both but I cannot see different CAS numbers. The sulfate itself seems available as either a Sodium or Potassium salt.

Any thoughts?


texts: Fluorochrome (fluorescein) emission decay when linked to macromolecule

texts:
I measure the intensity and polarization of light emitted from a blood sample that contains excited fluorescein (experiment known as fluorescence polarization assay). The excitation is done, as usual, with vertically polarized light.
In case the sample has certain macromolecules of interest (an antibody, in this case), the fluorescein links to the much-larger macromolecules, yielding a higher polarization factor, giving a positive- or "sick"- result. Alternatively, if there is no antibody, the excited fluorescein randomly rotates and then emits light, and the polarization factor is smaller giving a negative-or "healthy"- result.
The question:
I find that the light intensity (in both vertical and perpendicular polarizations) decreases for the positive case. Why is that so? Could it be that a non-radiative process like FRET acts stronger for fluorescein linked to macromolecules than for free fluorescein?
EDIT 1: I have used two different intensity detection systems, PMTs and SiPMs, and got similar behaviours.


texts: How to simulate a Lorentzian broadened spectrum in MATLAB?

texts:
I'm trying to simulate the 2nu2 band of HCN in MATLAB. I generate a stick spectrum from the data I have (taken from the HITRAN database) and then use conv() to apply my line shape function. However, when I plot the data, the broadened spectrum does not line up with the stick spectrum at all. I cannot figure out what it is that I'm doing wrong or what I need to change to align the spectra. Does anyone know what is I need to fix or a resource I could use to solve this issue?
This is the spectrum I've simulated:

and the function I use to generate the spectrum is
function f = func()
HCN2nu2 = importdata('I:/HCN 2nu2.txt');
HCN = HCN2nu2(1:111,1:2);
AX = HCN2nu2(1:111,2);
v = [];
s = [];
L = [];
q = 1;
p = HCN(q);
increase = false;
for i = 6200:0.01:6700
    for x = 1:111
        if i == round(HCN(x,1), 2)
            z = AX(x);
            increase = true;
            break
        else
            z = 0;
        end
    end
    v = [v; i];
    s = [s; z];
    if increase == true
        q = q + 1;
        increase = false;
        if q > 111
            q = 111;
        end
    end
    t = (1/(1 + ((i - p)/0.5)^2));
    L = [L; t];
end
hold on
plot(v,s)
k = conv(L,s, 'same');
plot(v,k)
ylim([0 8e-21]);
hold off
end

Any help would be greatly appreciated
Link to the data file used to generate this spectrum:
https://github.com/tkh97/HCN-2nu2.git


texts: In UV spectroscopy, when a beam of light is shone into solution, what is scattering loss during this process?


texts: Chemical Spill in Charleston, West Virginia

texts:
I live in Charleston, WV.  On 1/9/2014 we were told not to use our tap water for anything other than flushing the toilet after a storage facility leaked over 7,400 gallons of 4-methylcyclohexane methanol into the Elk river, less than two miles up-river from the water company's main in-take.

The CDC said that concentrations under 1ppm were safe.  After a week of bathing in my sink and drinking bottled water, my area was determined to be safe, however my water still has a strong odor.

There is not much information about this chemical's health effects.  While the chemical itself is low-toxicity, I wonder if it might react with items in the water supply to create other compounds which may be more toxic.

Specifically, would this chemical react with chlorine in the water, or cast iron, PVC, and copper in the pipes?  Does anyone have any experience with this compound?


texts:
To derive the Lever rule, the textbook I am reading sets:

$$nz_A = n_\alpha x_A + n_\beta y_A\\ nz_A = n_\alpha z_A + n_\beta z_A$$

$x_A =$ liquid phase mole fraction of component $A$

$y_A =$ gas phase mole fraction of component $A$

$n_A=$ amount of phase $A \ \text{in mol}\ (A=\alpha \ \text{or} \ \beta)$

$z_A=$ overall composition

"Overall composition" sounds to me like $z_A=x_A+y_A$, but the equation suggests $x_A = z_A = y_A$ which doesn't make sense so I think I'm missing an assumption that is made or I'm misunderstanding the equation.


texts:
My answer: The inert pair effect in $\ce{Pb}$ causes it to pull back the electrons, resulting in polarisation.

My teacher's answer: An ionisation state of $+4$ is too difficult to achieve, and it is not gained even when 4 chlorine atoms get reduced, as the later ionisation enthalpies of lead (or any metal) are high.

My point is, if we don't think of the inert pair effect, we are generalising this, and moreover, high ionisation energies of lead should be explained by the inert pair effect.

Which explanation do you think is better?

As a side note, I would like to add that my teacher pointed out that the inert pair effect is an outdated concept. Is it so? If yes, why is it rejected?


texts: Calculate Work Done for Reversible and Irreversible Adiabatic process

texts:
How to calculate it.

Work done for adiabatic process is (P1V1 - P2V2)/(γ-1) but this is also the work done for reversible process. How?

And How do we calculate for irreversible?


texts: I've read at many places that temperature is the average kinetic energy of particles present in an object. I just don't intuitively get how kinetic energy is connected with temperature. And how is heat connected with temperature then? Then what exactly is temperature? All of the descriptions given online are very confusing.


texts: If I have $X$ moles of a gas and I put them in a container at constant volume $V$, will the molarity of the gas then be $X/V$?


texts: Crystal Field Explanation of Colors of Coordination Compounds

texts:
Crystal Field Theory explains colors of Coordination compounds as follows : A d-orbital splits into multiple orbitals, the process being called crystal field splitting. When white light falls on the compound, an electron makes a transition into a higher state thus absorbing a particular wavelength of light. The rest of the light is reflected. This reflected light is responsible for the color of the compound.

Problem: Suppose, all electrons have now transit into a higher state. If more light falls on the compound, there should be no more transitions as all the electrons are already in the highest state. This means the compounds should lose color after some time in the light.

Question: How is the light absorbed again and again? If we suppose that the electron falls back to lower state, that would emit the same wavelength it absorbed. Even in this case, how do we explain color?

P.S. Also, if they can absorb only a particular wavelength(given quantisation), that should not bring about a color change. There must be a range of wavelengths(however narrow) being absorbed. What is the reason for that?


texts:
Can Michaelis-Menten constant be zero in the Michaelis-Menten Equation, or is this a non-zero constant?

I am applying the equation in epidemiology so I wanted to assume that it is zero but I am not sure if it is possible for this constant to be zero?


texts: Chemical shift difference methyl groups in 4-hydroxy-2,5-dimethyl-3-hexanone

texts:
Can someone explain why the NMR Spectrum of 4-hydroxy-2,5-dimethyl-3-hexanone shows a chemical shift difference for the methyl groups at the end? Why aren't the other carbons have a difference?
Below you see the NMR spectrum:


texts: Szabo and Ostlund's calculation of repulsion integral on page 172 via A.41

texts:
Returning to Szabo & Ostlund after a hiatus I tried to recreate his STO-3G calculation for HeH+ which begins on p. 168. It all went fine except for the two-electron, two-center integrals. I employed Szabo's values for these on p. 172 and was able to get his result for the energy and so on.
What I was not able to do is duplicate his p. 172 values for the 2-e integrals from his expression on page 416 (A.41). For example, on page 172, he gives $(\phi_{1}\phi_{2}|\phi_{1}\phi_{2}) = .1773.$
There are other approaches to this problem and I have looked at a few, but I would like to understand it as Szabo presents it. Because I was able to get the nuclear repulsion terms and so on I think my expressions for the contracted gaussians are fine but am misinterpreting some aspect of (AB|CD) in A.41.
If anyone is familiar with this particular calculation, and could show the proper calculation of (say) (12|12)...This is a very picayune question in the sense that I am interested in the particular calculation in Szabo: how to get 0.1773 on p. 172? Thanks for any illumination.
Edit
The Fortran program alerted me to a confusion. The "contracted" gaussians, using (11/11) as an example, look like:
$$G_a= .444635(2a_1/\pi)^{3/4}e^{-a_1|r-R_A|^2}+.535328(2a_2/\pi)^{3/4}e^{a_2|r-R_A|^2}+.154239(2a_3/\pi)^{3/4}e^{a_3|r-R_A|^2}$$
Regardless of how we do the integral it is:
$$\int G_a^2 \frac{1}{r_{1,2}}G_a^2$$ and we are raising the coefficients associated with $G_a$ to the 4th power and they come out of the integral. If we could do this integral in the usual naive way using linearity we would have 81 terms (some repeated) involving constants like:
$$(d_id_jd_kd_l)(2a_i/\pi)^{3/4}(2a_j/\pi)^{3/4}(2a_k/\pi)^{3/4}(2a_l/\pi)^{3/4} $$ where $i,j,k,l$ range from 1 to 3 respectively, where the $d_i$ are the coefficients $0.444365,$ etc.
That is why on p. 420 in the fortran program the quantities D1 include weights as factors, and a product of four D1's are pre-multiplied on p. 421 by the constants calculated in "TWOE" on p. 423. Using Fourier transforms to do the integral does not change the constants.
In short, the program is doing a lot of work here. It should still be possible to exhibit (11/11) easily but no wonder A.41 is not used in practice--it represents no economy over the fortran.


texts: Does the mole fraction of a solution change with Vant Hoff factor?

texts:
I reason that as mole fraction is a measure of colligative properties, increase in the Vant Hoff factor ( and hence increase in the value of colligative properties) should also leave a mark on the mole fraction of the solute components.
However, my instructor tells differently.


texts: Reaction of multiple diols with sulphuric acid

texts:
Find the total number of possible products

I can think of atleast three reactions that will take place in the acidic medium:

Pinacol-Pinacolone rearrangement
Intermolecular dehydration (leading to ether formation)
Intramolecular dehydration (epoxide formation)

Here are the possible products that would be formed:

This gives us a total of $8$ possible products.

Are any different reactions possible? Also, are any of the products that I have listed wrong? (Will any of them not be formed).


texts: How to determine the number of water ligands attached to Pd in palladium chloride aquacomplex PdClₓ · yH₂O?

texts:
Normally this can be achieved using UV-vis: there is a strong absorbance around wavelength 220 nm which varies based on the number of ligands. If the palladium concentration is too high, the solution can be diluted.

However, in my case I do not know the concentration of solution as the solution is reactive. I need to measure the palladium ligands after these reactions have occurred. Thus dilution is not an option. Does anyone know if UV-vis can be tweaked or another technique for testing palladium-water speciation in solution?

FYI I get an absorbance value of 4 (the peak is still quite broad at this value) when testing the palladium chloride under the desired conditions.


texts:
I boil natural spring water (Evian) in a stainless steel kettle and there is a white residue left behind that I can wipe off with a wet paper towel. What is this?
I also notice residue floating in water remaining on bottom of kettle. This does not happen with regular tap water.


texts: Is there a concise notation for a solution of one substance in another?

texts: I'm aware of phase notation of $\ce{(aq)}$ for aqueous solutions. Is there something similar for solutions of chemical X dissolved in chemical Y?


texts: Reaction of ethene with ammonia and sodium

texts:
Is the following sequence of reactions correct?

$$\ce{CH2CH2 ->[][\ce{NH3},\,\ce{Na}] NaHC=CHNa}$$

$$\ce{NaCH=CHNa + 2CH3CH2Br-> CH3CH2CH=CHCH2CH3}$$


texts: Can a copper(II) chloride be added to liquified butane?

texts:
What would happen to either chemical if the two were mixed together, specifically what would happen if the dust was mixed in when the Butane was in an aqueous state.

I have a limited knowledge of chemistry so I apologize if my terms are incorrect.


texts: Is there any material that can prevent silver from tarnishing?

texts: I am designing a machine that uses paper-thin sheets of silver. I am trying to find a material that can cover the silver to prevent it from tarnishing over time. The material does not have to be abrasive-resistant, as the silver will be placed in a controlled environment. Because of this, appearance does not matter. Perhaps aerogel can work?


texts: Metal-Ligand-Complex and bond directions: What defines coordinate system of the complex ion?

texts:
I have a question concerning metal ligand complexes.

In every chemistry text book I have read which treats metal ligand complexes, following situation is discussed:
When 6 ligands (in octahedral coordination) approaches a metal ion with d-orbitals, 2 of the three orbitals are energetically raised because these orbitals have their lobs in direction of the ligands.

But why is this always true?
Why does always point the lobes of the z² and x²-y² orbital towards the ligands coming from "above" and "below"? Isn't it possible, that the z-axis of orbital system of the metal is a little bit inclined with respect to the octahedral ligand system surrounding the middle metal ion?

The only thing I can think of, is that this is because of energetic reasons. That in total, it's energetically more favourable when 3 of the 5 d-orbitals are arranged, so that electron occupying these orbitals have the lowest possible energies.

But up to now, I haven't found anything discussing this question.

Thanks in advance,
Jürgen


texts: Do hydrogen peroxide stabilizers affect oxidizing ability

texts: I plan to use hydrogen peroxide for a redox reaction in oxidizing $\ce{I-}$ to $\ce{I}$.  I found 20 volume hydrogen peroxide as a hair developer, but it contains stabilizer.  I imagined these would have little effect on its oxidizing potential, but I wanted to make sure.  Will any of the common stabilizers used for hydrogen peroxide inhibit its oxidizing ability.


texts: Does the dispertion medium affects Quantum Dots fluorescence efficiency?

texts:
I would like to use CdTe Quantum Dots to make a fluorescent coating on a transparent support. There's a link to the material here: http://www.plasmachem.com/shop/en/62--cdte-quantum-dots-powder-hydrophilic-water-soluble

I observed that the fluorescence of these QDs is much higher when they are dispersed in water than when they are dispersed in a dry layer of acrylic.

Wondering why this happens, and being a very bad chemist/physicist myself, I was wondering if this loss of fluorescence was due to some physico-chemical interaction between the media (acrylic) and the QDs.

Does the interaction between the media and the surface of QDs affects in some way the luminescence mechanism of QDs? Or is it more a problem of structure, e.g. the QDs are "clustered" in the thin layer of dry acrylic while they are distant from each other in water?

Another simpler way of saying all that would be: what is the best media to make a fluorescent QDs coating? (I was thinking of acrylic or epoxy resin...)

(I also posted this question on the physics StackExchange)


texts: How to treat pressure in computational chemistry?

texts:
I have a reaction where a gas at high pressure and a solution with all kinds of species is involved. How do I take pressure correctly into account to get reasonable values for $G$?
Do I calculate thermochemical corrections at the given temperature and pressure (frequency calculations) and then add additional corrections for concentration ($\Delta G = RT \ln(p)$, where $p$ is (partial) pressure or mole fraction)? Or should I calculate the thermochemical corrections at the given temperature, but standard pressure? For the additional term, should I use the overall pressure of the gas, and the mole fraction of the species in solution, or should I check for the solubility of the gas at given temperature and pressure in the solvent?
Usually, I would approach it this way:
Geometry optimization at lower level of theory, then computation of $G$ as the sum of:

single point energy at higher level
$G$ thermodynamic corrections (at $\pu{298.15 K}$ and $\pu{1 bar}$)
$G_\mathrm{solv}$ corrections from COSMOtherm (at infinite dilution)
$\Delta G_p = RT \ln(p)$, where $p$ is either the molar fraction of the compound in solution or the partial pressure in gas phase

This works quite well, however, I'm not sure how to adjust the different terms when dealing with non-standard conditions. I think that as only dissolved gas participates in the reaction, I should be interested in this as a reference point for $\Delta G_\mathrm{r}$, etc., but with what temperature/pressure do I then calculate 2? And do I take the pressure of gas above the solution in 4 or the molar fraction of gas in solution?


texts: Under which criteria HNO3 is a concentrated or a diluted acid?

texts:
I would like to buy nitric acid to remove impurities of copper on an aluminum plate. I read that a 10% nitric acid will do the job. However I've also read that concentrated nitric acid is very corrosive to human skin.

So is a 10% nitric acid solution is still very corrosive to human skin. What am I risking if one drop falls on my arm?

Is there any tables that shows the reactivity of acids under various concentrations to human skin?


texts: Are there other carbon free gasses that can be used for energy transport, apart from hydrogen?

texts:
Various gasses are currently used to transport and store energy for heating and electricity generation.

Most of them contain carbon:
Methane, propane, butane, carbon monoxide and natural gas.

It could be of advantage to use gasses that do not contain carbon.
One example for that is hydrogen.

Are there other gases that theoretically could be used, if they could easily be created?
I assume most can not practically used because they are not trivial to generate, but I like to ignore that, and assume they can be created.

Are there other gases that could be used, in principle, as energy carrier?


texts: Difference between voltaic cell in chemistry and battery in physics

texts:
In chemistry's voltaic cell, the anode (negative electrode) of the battery supplies electrons to the cathode (positive electrode) of the battery.

In physics, the electrons flow from negative terminal (cathode) of the battery to positive terminal (anode) of the battery. I don't nderstands this because in thermionic emission, electrons flow from cathode to anode too through an electric source ( which i believe is a voltaic cell). I dont understand this. Please help. Thank you.


texts: Elimination of OH from spirocyclic compounds

texts:
I was wondering, what would happen if I treated the following compound i.e. trispiro[2.1.25.1.29.13]dodecane-4,8,12-triol with sulfuric acid[$\ce{H_2SO_4}$] to eliminate OH group to form double bond:

Will the double bond form? if yes then where and why? If no then what other compound will form and why?


texts: About the nomenclature: manganate or manganite?

texts:
I am a bit confused about the correct name of $\mathrm{LaMnO}_3$. Is it lanthanium manganate or lanthanum manganite?

I was assuming that since $\mathrm{SrTiO}_3$ is called strontium titanate, $\mathrm{LaMnO}_3$ would then be called lanthanium manganate, but I got confused when I heard a collegue referring to it as manganite and after reading a wikiepdia article on $\mathrm{La}_x\mathrm{Sr}_{1-x}\mathrm{MnO}_3$ where they also used the term manganite.

Which is the correct form, or are they simply interchangeable?


texts: Proteins are heavy and not so volatile. Does it mean that pure proteins do not have a smell?


texts: What is the mechanism of the reaction between hexane-2,5-dione and nitrous acid?

texts:
I don't understand the mechanism of the first reaction; I tried different ways but I can usually find how to make the ring without the double bonds, but it's obviously not the right thing; I think HNO2 reacts as the nitrosonium ion, bonding with one of the oxygens (since it has free electrons) but I can't never make it work.

EDIT:
Probably the acid is formed by nitric acid (like in one of the articles orthocresol linked), that I think is not written because it can be formed by the decomposition of nitrous acid; I still don't understand the mechanism of the formation of the ring.

Image: https://commons.wikimedia.org/wiki/File%3AIsocarboxazid_synthesis.png
by Nuklear (Own work) [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons


texts: The Conductivity of Electrolytes based on structure of Ionic Crystal

texts:
Background
I want to run an  experiment to test the conductivity of various ionic compounds dissolved in water. I was hoping to see some sort of trend in the increase/decrease of conductivity based on my choice of salts. Except, conceptually, I don't quite get how my choice in the different compounds would affect conductivity.

Problems

I am somewhat aware of Kohlrausch's Law, but for my experiment I was not seeking to change dilution, temperature or electrode distances. What I wanted to do was to study the effect of the structure of ionic compound or charge of the ions on Conductivity.

I also wanted to compare my conductivities to some literature values.

Question
Just so this isn't a waste of time, I would like to know:

Does the structure of an ionic compound or the charge of its ions affect its conductivity, given that dilution and temperature will remain constant?
If so, how?
Is there a reliable Databse I can compare my results with?

I'm not too fussed about which ionic compounds they are, I would just like to understand how the compound itself plays a role in conductivity so I can confirm it with my experiment?
Thank you so much,

TL;DR
In a solution containing a dissolved ionic compound, to what extent is the ease of mobility of electrons or conductivity affected by either the electrophoric drag (presumably of polar water) and/or by the original structure (lattice shape) & charge of both the metallic and non-metallic ions?


texts: Can you artificially create molecules with a machine?

texts: Is it possible to create molecules with machines? For example: you shoot one oxygen-atom $(\ce O)$ on one diatomic hydrogen $(\ce{H2})$ to create one water molecule $(\ce{H2O})$.


texts: Why is a drop of chloroform stretched/pulled apart on a water surface?

texts:
I distributed drops of chloroform (with a lipid in them) on water (in a Langmuir-Blodgett trough). The chloroform drops form a layer on the water (so that the lipids are distributed on the water surface) and I need to explain why. (Afterwards, the chloroform evaporates, leaving back a lipid monolayer.)
I was told that the water pulls each chloroform drop apart and that this has to do with the fact that the surface tension of water to air is greater than the sum of the surface tension of chloroform to air and surface tension of chloroform to water.
Can someone explain how this works in more detail?


texts: Use of Na2S2O3 before starch in Winkler's method

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In Winkler's method why is some amount of $\ce{Na2S2O3}$ added before addition of starch solution turning the deep straw coloured solution pale straw?

Is it to generate $\ce{I-}$ ions needed for formation of $\ce{I3-}$ in the $\ce{I2}$ containing solution? This $\ce{I3-}$ inturn reacts with the starch to form blue-black complex.

However once we didn't add $\ce{Na2S2O3}$ and the addition of starch solution did turn the solution it blue-black.


texts:
For this multiple question:

The correct answer is B. However, I don't understand.
You are halving the volume
so for the original solution
the number of moles of HCl is 0.1 moles
and in the new solution, the number of moles of HCl is 0.05 if we are using the same concentration.
Therefore as there are less number of moles, won't the temperature increase (ie. energy release) get halved?


texts: Insight into covalent bonds from electrostatic perspective

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I try to understand, from the electromagnetic side only, how the molecule could be more stable than each atom, and concluded that it could not. Where is my mistake?
Here is an illustration :
By using a ruler in order to have an "example" of numerical values, we conclude, by taking the numerical values of distance in the electric field formula (I removed the common factor with $\epsilon_0$, $\pi$, etc.), that the repulsion force is bigger than the attraction force.
So where is the mistake in my reasoning ?
(I try to stay at a very basic approach of fundamental law of electromagnetism, so not using LCAO with quantum mechanics)


texts: Balanced equation for synthesis of p-nitrophenol from p-nitrodiaznoium chloride salt and sulfuric acid/water?

texts:
I am trying to write a balanced equation for the above mentioned reaction but having some trouble figuring it out. So far, I have:

$$\ce{([C6H4N3O2]+ Cl^{-}) + H2SO4 + H2O -> C6H5NO3 + N2 + ?}$$

How do I "incorporate" sulfuric acid and water into the reaction? Thanks for any help.


texts: Why isn't standard Gibbs free energy always zero?

texts:
I read in my textbook that one of the standard conditions we should use when calculating the standard Gibbs free energy is having a concentration of 1 M of all the reagents and the products in the reaction. But if you use the formula $G = -RT\ln K_\mathrm e$ and you use 1 M to calculate it, you would always get zero.

So that means 1 M would be the initial concentration of reagents and products before reaching equilibrium?


texts: Geometry of the pentachloridoindate(III) anion

texts:
According to Brown et al.,1 the crystal structure of $\ce{[NEt4]2[InCl5]}$ reveals that the pentachloridoindate(III) anion, $\ce{[InCl5]^2-}$, adopts a square pyramidal $C_\mathrm{4v}$ geometry (VSEPR theory would predict trigonal bipyramidal $D_\mathrm{3h}$):

According to Greenwood and Earnshaw,2

  It will be noted that $\ce{[InCl5]^2-}$ is not isostructural with the isoelectronic species $\ce{[SnCl5]-}$ and $\ce{SbCl5}$, which have the more common $D_\mathrm{3h}$ symmetry. […] $\ce{[NEt4]2[TlCl5]}$ is isomorphous with $\ce{[NEt4]2[InCl5]}$ and presumably has a similar structure for the anion.

However, the structure of $\ce{[PPh4]2[InCl5].MeCN}$ was reported to have the usual trigonal bipyramidal structure for the anion,3 which throws a spanner in the works. I can't understand much of the paper as it's in German. Since it's a report of a crystal structure, though, I don't really expect it to say much about the chemistry of the compound.

Can the reported differences in molecular geometry here be rationalised?

References

Brown, D. S.; Einstein, F. W. B.; Tuck, D. G. Tetragonal-pyramidal indium(III) species. Crystal structure of tetraethylammonium pentachloroindate(III). Inorg. Chem. 1969, 8 (1), 14–18. DOI: 10.1021/ic50071a004.
Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements, 2nd ed.; Butterworth–Heinemann: Oxford, U.K., 1997, p 238.
Bubeinheim, W.; Frenzen, G.; Müller, U. Die Chloroindate $\ce{[PPh4]2[In2Cl6]}$ und $\ce{[PPh4]2[InCl5].CH3CN}$. Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 1995, 51, 1120–1124. DOI: 10.1107/S0108270194011789.


texts:
$$\ce{C6H12O6(s) + 6 O2(g) -> 6 CO2(g) + 6 H2O(g)}$$
When looking at glucose combustion I found that the change in Gibbs free energy is greater than the change in enthalpy. If we assume the process is reversible we can set the change in Gibbs free energy to be the work available and if we assume there is no work we can set the enthalpy to be the heat. Why then would the work be less than the heat? I suspect that $\Delta G = \Delta H-\Delta (TS)$ is at work.

Cool, so can you substitute work, W and heat, Q into the equation and write W=Q−TΔS to directly show that ΔS>0? Also would you please explain how an increase in entropy would imply the discrepancy between heat and work (not mathematically).


texts: Why does high blood gas partition coefficient of a inhalational anaesthetic drug mean slower induction of anesthesia?

texts: High blood gas partition coefficient of a drug corresponds to higher solubility of the drug in blood leading to high concentration of the drug in blood with respect to gas (air in alveoli). If the drug is present at high concentration in the blood, wouldn't it correspond to faster delivery to target tissues-leading to faster anaesthetic effects or induction? What is meant by "more time is required to attain partial pressure in blood for induction" if the drug has high blood gas coefficient"?


texts: Why is the difference between atomic radii of Na and K greater than that of Rb and Cs?

texts:
I am aware that this question has already been asked here: Why does the "gap" between atomic radii get smaller down the periodic table?.

However, I was wondering if there is a way to answer this question using simple periodic trends instead of a formula to calculate atomic radius.

Since there is not only an s and p-block between Rb and Cs, but also a d-block, wouldn't the increase in shielding between Rb and Cs be higher than that of Na and K? Thus, shouldn't Rb and Cs have a larger difference in atomic radii?

I got this question in my chemistry class while learning about periodic trends, and it apparently also appeared on the 1993 AP Exam, so I would think that this problem could be explained using simple periodic trends.


texts: How many stereoisomers are possible for 1,2-dimethyl-4-(propan-2-ylidene)cyclopentane?

texts:
How many stereoisomers (not counting different conformers) does 1,2-dimethyl-4-(propan-2-ylidene)cyclopentane have?

I think the answer should be 3. There are two geometrical isomers (cis and trans) considering the two methyl groups on the ring, and the trans isomer will also show optical isomerism as it doesn't have a plane of symmetry. But in my book, the answer is given as 2. Is this a misprint?


texts: Are phenols good antioxidants? If so what makes them good? I think it is because they oxidize easily but I'm not sure how that helps.


texts: Are there any negatively charged electrophiles, or simply neutral and positive?

texts:
When reading up on electrophilic aromatic substitution, most resources refer to electrophiles as positively-charged species, "in general" or "mostly".

What are non-positively charged electrophiles? Are they simply neutral atoms/molecules more willing to gain electrons due to having less grasp on their own electrons? Are there any, as strange as it sounds, negatively charged electrophiles?


texts: Is an aqueous solution of potassium bicarbonate acidic or basic in nature?

texts:
The following is the definition of an acid salt according to my textbook:
The salts formed by the partial replacement of the replaceable hydrogen atoms (H+ ions) of an acid molecule by a metallic or ammonium ion are called acid salts. Acid salts ionise in water to give hydronium ions and therefore, their aqueous solutions show all the properties of an acid.
Going by this definition, potassium bicarbonate should be classified as an acid salt. Hence, an aqueous solution of potassium bicarbonate should be acidic in nature(as hydronium ions would be present in an aqueous solution of potassium bicarbonate).
However, my textbook also says, “The aqueous solutions of salts formed by a weak acid and strong base (as a result of a neutralisation reaction) are basic in nature.”
According to this, potassium bicarbonate solution should be classified as a solution which is basic in nature as potassium bicarbonate solution is formed as a result of a neutralisation reaction between potassium hydroxide, which is a strong base and concentrated carbonic acid, which is a weak acid even in its concentrated solution form.
So is potassium bicarbonate solution acidic or basic in nature?


texts: Why are double bonds at more substituted carbon more stable?

texts:
That $\ce{C=C}$ bonds are more stable at more substituted carbon  atoms is a common argument used throughout Clayden et al., but is never actually explained (at least not in the first 21 chapters). They do explain however, why the HOMO is increased in energy for more substituted double bonds, through the argument of electron donation by means of hyperconjugation of neighboring groups, increasing the electrophilicity of the $\ce{C=C}$ bond.

I find this somewhat counterintuitive. Usually when something is more reactive, it is less stable (I understand that of course by kinetic pathways this does not always hold, e.g. with $\ce{I-}$ as nucleophile).

How can both observations be incorporated in a consistent explanation in this case?


texts: Can sodium borohydride reduce hemiacetals?

texts:
In the synthesis of Panacene by Canesi et al. [1], a step involves the installation of an $\ce{-OH}$ group on a double bond, using the oxymercuration-demercuration procedure. However, the product happens to be a hemiacetal, as shown in the picture. With a 78% yield, it seems that the hemiacetal is not reactive towards the added sodium borohydride. Is this true in general, that hemiacetals will not be reduced to diols by $\ce{NaBH_4}$? What about $\ce{LiAlH_4}$?

References

Cyrille Sabot, Didier Bérard, Sylvain Canesi, "Expeditious Total Syntheses of Natural Allenic Products via Aromatic Ring Umpolung," Organic Letters 2008, 10(20), 4629-4632 (DOI: 10.1021/ol801921d).


texts: How to find the formula of an binary oxide based on the ionisation energies?

texts:
I am a little confused about this multiple choice question and what the requirements are to answer it. It is for a year 11 chemistry student that I am helping and I think I am going in a little too much detail to try to solve it to help them. I am sure that I am overthinking this.

  The energies needed to remove electrons in succession from a neutral
  atom of a certain element $\ce{A}$ are given ($\mathrm{kJ\cdot  mol^{-1}}$): $1010$, $2032$, $7056$, $8120$, $9300$.
   The formula  of the oxide of $\ce{A}$ is:
   $\ce{AO}$, $\ce{A2O}$, $\ce{A2O3}$, $\ce{A2O4}$ or $\ce{A3O5}$.

My understanding of the question and what I was trying to do to solve the problem by looking at the ratios between the energies and I was trying to apply
1st ionization energy: $$\ce{X -> X+ + e−},$$
2nd ionization energy: $$\ce{X+ → X^2+ + e−},$$
and 3rd ionization energy: $$\ce{X^2+ -> X^3+ + e−}$$
to the energies below and find a ratio. I thought the ratio was going to be c. I understood that oxide is $2-$, however, I couldn't calculate the $\ce{A}$ value as I didn't know what the element was.


texts:
I need a little help on answering a question which popped into my head while I was reading about gas laws:

  Suppose that I have three canisters, each holding a different gas of
  unknown identity [let's call them gasses A, B, and C] . I also happen
  to have another tank of a different volume in which these gasses can
  be mixed as I please, and a pump to remove the gasses from the mixing
  tank afterwards. Each of these containers is fitted with a pressure
  and temperature gauge. Furthermore, I have a heating apparatus which
  can be used to heat or cool the gasses inside any of the containers. I
  want to determine the molar heat capacity of each of the gasses.
  Assuming that no energy is lost to heating of the containers, is it
  possible to determine the molar heat capacities of gasses A, B, and C
  using this setup? If so, how? If not, why not?

I presume that yes, it is possible to do so. I'm thinking that, for instance, gas A at room temperature could be pumped into the mixing chamber, then the amount of moles of gas A in the mixing tank could be calculated using the PV=nRT formula. Then, gas B could be heated up to a certain temperature and pumped into the tank. Based on the fact that we know the amount of moles of gas A in the tank and the change in temperature and pressure, we can calculate the amount of moles of gas B. Afterwards, the mixing tank can be purged and a different combination of gasses can be pumped in. Rinse and repeat. Afterwards,I would get a system of equations that looks something like the following:

AF=BG

BH=CJ

CN=AL

Where A, B, and C are the heat capacities of each of the gasses, and F,G,H,J,N, and L each equal the amount of moles of a particular gas multiplied by the observed change in temperature and are known. Solving for A, B, and C would yield the molar heat capacity of each gas.

Is my reasoning correct?


texts: Intermolecular interaction Van Der Waals

texts:
In the empirical demonstration of the Van der Waals equation at Khan Academy, they made a demonstration of the real volume, for example, it was said that it has to be larger than the ideal volume, since the size of the molecules is not disregarded, hence it would be:
$$ V_{\text{ideal}} = V_{\text{real}} + nb $$
Where, $ b $ was said to be related to the size of the molecule.
But why don't I also include intermolecular interaction? Depending on it, the volume may even be smaller.


texts:
I have an intriquing question and, after searching whole Google, found almost no information. I simply don't know where else to look for answer and so I am asking you.

When I was a child, my parents travelled with me to Egypt and there, they bought me a little scarab beetle carved of some stone, about 5 cm long, 2 cm width and height. The stone is white-ish and translucent and glows green in dark (for some time). I only remember that it might (just a speculation) have been in Luxor in Alabaster workshop. But, according to online sources, Alabaster is not supposed to glow in dark, so what is it then?
Can you please tell me?

Oh yea, right. Here are some images. The fluorescence is really weak and doesn't last longer than 5-10min so I am sorry for a bad photo, just couldn't make it better.

Daylight 01

Daylight 02

Daylight with flash

Daylight against sun 01

Daylight against sun 02

Fluorescence

Well, it doesn't look like Fluorite to me(according to Google images) but then again, I'm no mineralogist either so, maybe it's some form of it... what do you think?


texts: Why is the ionization energy of sulfur anion more than that of oxygen anion?

texts:
Which of the following are in the correct order of their ionization energies? (multi-answer question)

  $\ce{O > S > S- >O-}$
  $\ce{F > F- > Cl- > Cl}$
  $\ce{O > O- > S- > S}$
  $\ce{F > Cl > Cl- > F-}$

The answers are 1 and 4.

Why is ionization energy of $\ce{S-}$ greater than $\ce{O-}$? The sulfur ion has an extra shell than an oxygen ion, so the atomic size of sulfur should be greater than oxygen. Therefore, the ionization energy of an oxygen ion should be more than a sulfur ion because the electrons in oxygen are closer to the nucleus when compared to sulfur. But why is the reverse true?


texts: What is the exact definition of Salinity?

texts:
I am a bit unclear on the definition of salinity.  I have always thought of it as simply total dissolved ions.
Wikipedia seems to agree "saltiness or dissolved salt content" but many other sources seem to suggest that only certain ions contribute.
So is there a list of specific anions and cations that contribute to salinity and is there an underlying logic involved in their selection or is it simply arbitrary? Is the definition dependent on the solute in question?


texts: How can we replace volume in ideal gas equation with V - nb?

texts:
We know that ideal gas equation is $PV= nRT$ where P is the pressure of the ideal gas and V is the volume of the ideal gas. Thus, we can write :
$$ P_{\textrm{ideal}}V_{\textrm{ideal}} = nRT$$
Now from volume correction term of van der Waals' equation we know that
$$ V_{\textrm{real}} = V_{\textrm{ideal}} - nb $$ where $ V_{\textrm{real}} $ is the volume of the real gas and $ V_{\textrm{ideal}} $ is the volume of the ideal gas. Clearly, $ V_{\textrm{ideal}}$ and $ V_{\textrm{real}} $ are different.
Then how can we write :
$$P_{\textrm{ideal}} (V_{\textrm{ideal}} - nb) = nRT$$
How can we replace $ V_{\textrm{ideal}}$ with $ V_{\textrm{real}}$?


texts: Second ionization potential of Gadolinium

texts:
I notice that Gd has a second ionization potential which is significantly higher than would be expected from the general trend in the lanthanides (see this paper p. 945 for a graph). What is the reason for this effect ?

The transition corresponds to $[Xe] 4f^{7} 5d^{1} 6s^{2} => [Xe] 4f^{7} 5d^{1}$. I understand that the 5d is occupied to prevent inter-electron repulsion between antiparallel f electrons, and this can be used to rationalize why the correspnding Tb transition requires less energy, but I'm not sure why the potential should be significantly higer than that for Eu.


texts: Relation between the virial coefficients and van der Waals constants

texts:
I don't know where to begin with this question.

A function $f(x)$ can be expressed as a special power series called the Taylor expansion. The common expansion is $(1-x)^{-1}=1+x+x^2$ Note that the higher terms become neglibible small and usually are not included in expansion. Find the correlation between the virial coefficients and $a$ and $b$ in the corresponding van der Waals equation of state. Start with the equation shown below and compare it with the virial equation of state.
$$ p=\frac{RT\left(1-\frac{b}{V_{\mathrm m}}\right)^{-1}}{V_{\mathrm m}}- \frac{a}{V_{\mathrm m}^2}$$

The virial equation of state is

$$ p=\frac{nRT}{V}\left(1+\frac{nB}{V}+\frac{n^2C}{V^2}+\ldots\right)$$

I get that there are $A$, $B$, $C$… coefficients, and that the $A$ coefficient should be 1.
The best I have is that:
$$\begin{align}
A &= 1 \\
B &= -\left(\frac{b}{V_{\mathrm m}}\right)^{-1} \\
C &= -\frac{a}{V_{\mathrm m}^2}
\end{align}$$
If I were to relate that to the terms in the Taylor expansion, then $p=(1-x)^{-1}$ and then $A$, $B$, $C$… are the terms on the right side of the equation.
Is this the correct approach? Can the virial coefficients have a negative value?


texts: Is the %V/V composition defined for homogeneous mixtures?

texts: Why do major websites such as NASA and Wikipedia discuss the composition of the earth's atmosphere in terms of percentage by volume instead of percentage by amount of substance? Isn't the percentage composition by volume undefined since all gases in the atmosphere occupy 100% volume of it?


texts: How would one make a non-toxic pen out of osmium?

texts:
Osmium is the densest element in the periodic table. However, it is toxic in its pure form. Is there a way to create a standard pen out of osmium but coat it in a dense material that isn't toxic to have the heaviest pen?

How would this pen be made?

It would be a cap pen (like the Uniball pen pictured below) with no wasted space for plastic mechanical parts.


texts: Does the temperature of water affect its ability to extinguish fires?

texts: Since water can be either hot or cold, does its temperature affect its ability to extinguish fires?


texts: What chemical compound makes colour change to copper into brown like this?

texts: What chemical compound should I use to change the colour to make copper statue like this shown in picture


texts:
The following question was asked in an exam today:

I chose the option (a), but the correct answer given was (b). Following is the explanation why I chose (b):

Step 1 (Reaction with $\ce{PBr_3}$): $\ce{Br}$ substitutes $\ce{OH}$. Hence, the product is $\ce{CH(CH_3)_2Br}$
Step 2 (Reaction with $\ce{Mg}$ in the presence of dry ether): $\ce{Mg}$ gets inserted between $\ce{CH(CH_3)_2}$ and $\ce{Br}$. Hence, the product is $\ce{CH(CH_3)_2MgBr}$
Step 3 (Opening of epoxide and attacking of grignard reagent): First, the $\ce{CH(CH_3)_2MgBr}$ will break into $\ce{CH(CH_3)_2^-}$ and $\ce{MgBr^+}$. Then, $\ce{MgBr^+}$ will attack $\ce{O}$ of the epoxide. After that, $\ce{O}$ will take its electron away from 2nd $\ce{C}$ (referring to the catalyst used) due to the greater stability of secondary carbocation.
Further, $\ce{CH(CH_3)_2^-}$ will attack the carbocation and hence form the product $\ce{CH(CH_3)_2-CH(CH_3)-CH_2-OMgBr}$
Final step (Hydrolysis): On hydrolysis, $\ce{CH(CH_3)_2-CH(CH_3)-CH_2-OH}$ will be our product. Phew!

Where I am wrong and what should be the correct mechanism?


texts:
Is molar heat capacity and heat capacity

at constant volume both represented by $C_v$?
at constant pressure both represented by $C_p$?


texts: Misconception? "That gas is heavier so it sinks."

texts:
I've heard people say many times that one gas is heavier than the other so the heavier gas sinks. Now this must certainly be true to a certain extent (I think of gas used in WWI that sunk into trenches). However, this idea of the weight of a gas being a driving force seems unusual because, in my experience, entropy is the dominating motive for particles in the gas phase. A good example of this is that gas phase clusters are studied extensively in the literature due to how unusual they are.

So, why would some gases "sink" and give up their entropic gain for what doesn't seem to be much of an energy minimization? Could the answer be simply that this concentration of heavier gases is quite short lived and they soon float away to their entropy filled wonderland?

I would also give as an example the fact that CO2 certainly gets up high in the atmosphere quite well and that is more than twice the "weight" of other particles in the air. So what's different about that than about the examples given previously?


texts: Geometry of the transition metal complex in solid dipotassium bis(oxalato) copper(II) tetrahydrate

texts:
I was thinking of the geometry of the transition metal complex in solid $\ce{K2[Cu(ox)2] · 4 H2O}$ solid around the $\ce{Cu(II)}$ ion.
At first I thought square planar, but is it possible or is there any chance that it could be octahedral with two water molecules since it is a hydrate?
Or do brackets always indicate what is directly complexed in this case?


texts: Why is the hypoiodite anion unstable in solution, whereas hypochlorite is relatively stable?

texts: $\ce{Cl2}$ and $\ce{Br2}$ can disproportionate in a cold, aqueous, basic environment to form $\ce{ClO-}$ and $\ce{BrO-}$ respectively, yet $\ce{I2}$ directly forms $\ce{IO3^-}$. Why isn't $\ce{IO-}$ isolatable in solution?


texts: I'd like to know why my $\ce{TiO2}$ sol gel did not get coated nicely on my 200 gsm fiberglass? Here my solution, 5 g of tween 80, 40.15 ml isopropanol, 3.4 ml titanium isopropoxide, 0.62 ml sulphuric acid (0.02 mol).  Beside that, my $\ce{TiO2}$ sol gel can't calcinated at 500°C.  It will turn into powders and get burned into a black colour.  What should I do to overcome this problem?


texts: Why can't cyclohexylbenzene be called benzylcyclohexane?

texts:
The following structure represents the compound cyclohexylbenzene:

Why can't the benzene ring be treated as a substituent and the compound be called benzylcyclohexane?


texts:
A Kipp's apparatus has three distinct bulbs. The topmost one contains a liquid and a tube to the bottommost one. The middle one contains a solid to react with the liquid.

This is very understandable when large chunks of solid are used. However, what do people do when they need to react a powder (e.g. sodium sulfite)? It seems that the powder would just fall through and keep reacting when the valve is closed.


texts: I ordered Sodium Chlorite in the mail and received Chlorine Dioxide. Can they be used interchangeably, or are they different? My background in chemistry is limited so laymen's terms would be appreciated. I appreciate any responses or feedback.


texts: Which is the correct way to name pentan-3-one?

texts:
I have seen this organic compound named in two different ways.

According to some sources it is written pentan-3-one.. Other sources call it 3-pentanone.

Which one is correct?


texts: Will sodium metal, if mixed well with iron oxide, displace the iron in a chemical reaction? I know thermite involves the mixture of aluminium powder and iron oxide, and the single displacement reaction results in molten iron and aluminium trichloride. The other day I melted some sodium metal to the point of melting but reacting with the air. I wonder if either mashing up sodium with iron oxide and then igniting, or adding melted sodium to iron oxide will act like a thermite reaction.


texts:
In industry, it appears the alkaline water electrolysis is largely done with solutions of NaOH or KOH - presumably due to low cost.

I presume that alkaline water electrolysis is possible under RbOH, however, I can not seem to find any evidence in the literature showing the use of RbOH for water electrolysis. Can water electrolysis be done with RbOH to give oxygen and hydrogen gas evolution at the working (TiO2) and counter (Pt) electrode respectively?

Thanks!


texts:
100 mL of a 0.1 mM buffer solution made from acetic acid and sodium acetate with pH 5.0 is diluted to 1 L. What is the pH of the diluted solution?

The pKa value for acetic acid is given as 4.75.

The answer provided in my textbook is pH = 5.53. The closest that I can get to that is pH = 5.507. I know that's an almost insignificant difference but I'm just confused how they got to their answer, so if anyone can give me some suggestions that would be awesome. I'll outline my approach below:

Using the Henderson-Hasselbalch equation to find the ratio of [A-] to [HA] in the 100ml:
$$10^{5-4.75} = \frac{[A^-]}{[HA]}$$

$$[A^-] = \left(\frac{10^{0.25}}{10^{0.25}+1}\right)\times\left(\frac{0.1mM}{1000}\right) = 6.4{\times}10^{-5}M$$

$$[HA] = \left(\frac{1}{10^{0.25}+1}\right)\times\left(\frac{0.1mM}{1000}\right) = 3.6{\times}10^{-5}M$$

The addition of 900ml of water to 100ml of buffer is a 10x dilution:

$$[A^-] = 6.4{\times}10^{-5} \times 0.1 = 6.4{\times}10^{-6}M$$

$$[HA] = 3.6{\times}10^{-5} \times 0.1 = 3.6{\times}10^{-6}M$$

$$\ce{[H+]} = 10^{-5} \times 0.1 = 10^{-6}M$$

ICE table to determine equilibrium concentrations after dilution:

$$
\begin{array}{c|c@{hello}c@{}c@{}c@{}c@{}c@{}c}
   &   [CH_3 COOH] & + &[H_2 O] & {}\rightleftharpoons{} & [H_3 O^+] & + &[CH_3 COO^-] \\
\hline
I & 3.6 \times 10^{-6} && - && 10^{-6} && 6.4 \times 10^{-6} \\
C & -x && - && +x && +x \\
E & 3.6 \times 10^{-6} -x && - && 10^{-6} +x && 6.4 \times 10^{-6} +x \\
\hline
\end{array}
$$

$$K_a = \frac{\ce{[H3O+][CH3COO-]}}{\ce{[CH3COOH]}}$$
Then substituting in Ka and the equilibrium values from the ICE table: $$(10^{-4.75}) = \frac{(10^{-6}+x)(6.4 \times 10^{-6} + x)}{(3.6 \times 10^{-6} -x)}$$

$$x^2 + 2.518 \times 10^{-5}x -5.762 \times 10^{-11} = 0$$

$$x = 2.111 \times 10^{-6}$$ $$ [H^+] = 10^{-6} + 2.111 \times 10^{-6} = 3.111 \times 10^{-6}$$

$$ pH = -log_{10}(3.111 \times 10^{-6}) = 5.507 $$


texts:
I tried searching my question on google and did not find anything. I am looking to extract herbs with pure 100%
grape juice http://www.lakewoodjuices.com/product_detail/id-32/ ( it is pasteurized ) instead of using the old school
method of extracting with a 50% alcohol solution.My theory as of now would be that it would be more beneficial and it
would ferment or extract the same plus the extra beneficial minerals of the juice. I am wonder what your opinion on
this is. Do you think it would extract the same and be just as beneficial as a tincture? Would it be more beneficial?
How long should I let it sit for? should I let it sit at room temp or in cooler temp say, 45 degree F? Should I do neutral water dilution with the grape juice? how much, 50% neutral water 50% grape juice?
Thank you so much for your time and knowledge.


texts: Internal Energy Changes in Adiabatic Reactor

texts: If we consider adiabatic reactor (one which doesn't exchange energy and matter with surroundings) with some reaction in liquid phase, energy balance for such reactor is written as heat of reaction being equal to time derivative of enthalpy at any point in time. Since reaction is in liquid phase during reaction there are negligible changes in volume and pressure of reactor so that change in enthalpy is approximately equal to change in internal energy. Problem here is that how can internal energy (or enthalpy in this case) change in adiabatic reactor since it doesn't exchange energy with surroundings? Internal energy is a sum of all microscopic kinetic energy and potential energy of interaction of all bonds in the system. During chemical reaction interatomic potential energy is converted to microscopic kinetic energy (or vice versa) because of which temperature changes, but change in each type of energy must be equal due to energy conservation. Since this is the case internal energy doesn't change after reaction in adiabatic reactor. If so, why does equation of energy balance say it does change as temperature of system is changed during reaction?


texts: Reasonings on the pH of calcium carbonate in ammonium chloride solution

texts:
Consider calcium carbonate saturated in $1.0\:\mathrm{M}$ ammonium chloride solution. I have calculated the $\mathrm{pH}$ of this solution analytically (with mass and charge balance) to be $6.92$.

Now, how would the actual solution $\mathrm{pH}$ compare to the theoretical, calculated $\mathrm{pH}$ - in a general sense?

Would one expect the actual solution $\mathrm{pH}$ to be higher or lower than $6.92$?

I know that there are going to be a host of solute-solute interactions in this system that are more than likely to cause deviations from ideal solute behavior. Here's a list of species in the system:

$\ce{Ca^2+}$ and its respective hydrates
$\ce{CO_3^2-}$ and its respective protonation products (i.e. bicarb and carbonic acid)
$\ce{H_4N+}$ and its respective deprotonation products (i.e. ammonia)
$\ce{Cl-}$ and perhaps (unlikely) a bit of its protonation product - hydrochloric acid.
$\ce{H_3O+}$
$\ce{HO-}$

Now, the question I'm fundamentally getting at is how would all these solutes interact with each other. I understand that the calcium ion and the carbonate ion with their +2 charge magnitudes is likely going to cause this solution to deviate significantly from ideal behavior. A quick leafing through of an analytical text lead me to this hypothesis. However, is it possible to actually predict the direction, so to speak, of $\mathrm{pH}$ deviation? Can we model this system with a computer program?

Also, I plan on actually taking $\mathrm{pH}$ measurements on this system. Here is a general outline of the things I plan to do; is there anything else that I need to take into account?

Use of triple distilled water. Our laboratory's "deionized" water runs strongly basic. Water will be distilled with a high partial pressure of nitrogen gas as to prevent carbon dioxide from dissolving in water.
Should we measure $\mathrm{pH}$ in a sealed vessel? I don't want any carbon dioxide to be dissolving into the system, again. Also, I don't want any ammonia gassing off from the system (since ammonia is a possible product upon saturating ammonium chloride solution with calcium carbonate). How would measuring $\mathrm{pH}$ in a sealed vessel work?
Any other lab practical tips/suggestions?


texts: How can I properly calculate the isoelectric point (pI) of amino acids?

texts:
The following amino acid is called lysine. I was asked to calculate its isoelectric point, with the given $\mathrm pK_\mathrm a$ values.

I've searched a lot, and the most helpful post that I found was How do I calculate the isoelectric point of amino acids with more than two pKa's?
According to orthocresol's answer:

Since the $\mathrm{pI}$ is the $\mathrm{pH}$ at which the amino acid has no overall net charge, you need to average the $\mathrm pK_\mathrm a$ values relevant to the protonation/deprotonation of the form with no net charge.

Let's call the ends $e_1, e_2$ and $e_3$ (from left to right).
Approach $\#1$

deprotonate $e_3$ (i.e., carboxyl group)
deprotonate $e_1$ or $e_2$ [neutral point]

So, $\mathrm pK_\mathrm a$'s of $e_1$ and $e_2$ are relevant.
$$\Rightarrow \mathrm{pI} = \frac{10.53 + 8.95}{2} = 9.74$$
But, is there some limit to number of protonations/deprotonations or some procedures to follow?
For instance,
Approach $\#2$

deprotonate $e_1$
deprotonate $e_3$ [neutral point]
deprotonate $e_2$ and protonate $e_1$ [neutral point]

This time, $\mathrm pK_\mathrm a$'s of $e_3$ and $e_1$ are relevant. But, the calculated $\mathrm{pI}$ isn't correct.
So, how can I validate the approaches?

Problem source: FIITJEE study material
$\mathrm pK_\mathrm a$ and $\mathrm{pI}$ values table for amino acids: https://www.anaspec.com/html/pK_n_pl_Values_of_AminoAcids.html


texts: What's causing this dip in the FCS curve?

texts:
This is a fluorescence correlation spectroscopy measurement of light harvesting complexes. What could be causing the dip at 100 microseconds?

Edit:

The same thing was observed using fluorescence beads.

The only thing I have thought of is a problem reading in photon arrival times, or a problem with the laser.


texts: Spraying difluoroethane into an enclosed space

texts:
I'm working on developing physics lab activities that my students can do at home during the covid quarantines. For an activity involving waves and thermodynamics, I came up with an experiment at home in which I blow over the top of a bottle (beer bottle or 2-liter soda bottle), measure the frequency, and then spray a can of "dust-off" (difluoroethane) into the bottle and measure the frequency again. The frequency gets lower because difluoroethane is much more dense than air.

Environmentally, it looks like difluoroethane is fairly benign. It's used as an alternative to substances that are worse for our planet's atmosphere. People can huff it, and if you do, it's dangerous. It's flammable, so you want to stay away from flames and sparks. All of those things seem like they're not huge problems for my purposes.

But the label also says, "Never spray into an enclosed space, such as a trash can or paper shredder." What's up with this? That's exactly what I need to do for this experiment. Why is this dangerous?

Would there be any safety or environmental advantage to using 2,3,3,3-tetrafluoropropene ("Opteon" or R-1234yf)? It doesn't seem as readily available in small packages.

[EDIT]

Following up a comment by @MaxW: Interesting, thanks. I found a video of the liquid exploding when it's poured into water. Also a demonstration that it's flammable in gas form if you collect it in an open-topped container. Burning produces toxic $\ce{HF}$ and $\ce{COF2}$. So I'm hypothesizing (tell me if I'm wrong) that it's safe for my application if you (1) stay away from any source of ignition, (2) do it in a well ventilated area, and (3) in case of ignition, get away and let the fumes dissipate thoroughly. I'd be interested in answers as to whether this seems sufficient.


texts:
How can we look at reversible processes in an intuitive manner?

How is it possible, that at any moment, it can be reversed by an infinitesimal change?


texts: Calculate amount of enzyme needed for in vitro phosphorylation?

texts:
I have 100 micrograms of STAT1 and its molecular weight is 90 kDa. I calculated the number of moles to be 1 nmoles. The specific activity of JAK1 (the kinase) is 110 nmoles of phosphate per minute per mg of total protein at 30°C and the activity was determined at a final concentration of 0.83 micrograms/milliliters. What amout of JAK1 do I need?

I tried many ways but I don't get how to link the data.

Thank you.


texts: Why does diethylmethylamine have such a low melting point?

texts: According to PubChem, diethylmethylamine has a remarkably low melting point of $-196.0\ \mathrm{^\circ C}$. This is substantially lower than the melting points of dimethylethylamine ($-140.0\ \mathrm{^\circ C}$), trimethylamine ($-117.1\ \mathrm{^\circ C}$), triethylamine ($-114.7\ \mathrm{^\circ C}$), and 3-methylpentane (given as both $-162.9\ \mathrm{^\circ C}$ and $-118\ \mathrm{^\circ C}$, not sure which is right). Why is that? Is diethylmethylamine uniquely ill-suited to forming a stable crystal lattice for some reason (maybe its highly asymmetric structure)?


texts: Fermentation in beer (reaction schemes)?

texts:
I've been struggling with this for a while, and I can't seem to solve the problem. Alcohol is made in the fermentation process in beer:

  Sugars formed during mashing (maltose and maltotriose) will undergo hydrolysis and form multiple molecules of the simple sugar glucose. This glucose will then be fermented by the yeast under anaerobic conditions into ethyl alcohol and carbon dioxide

I understand that perfectly. My problem is to figure out the reaction schemes for the reactions, for each step. Can anyone help me with that?


texts:
Wax comes in all kinds (paraffin, bee wax, palm oil wax, gel wax, ...) but since it's usually a mixture of different carbonated chains, its physical properties vary a lot from one manufacturer to another.

A good candle is usually one made of a wax with a high melting point, such that it takes longer to burn.

I am trying to make a bad candle, more specifically I am trying to make a candles that produces as much wax vapor as possible. To make it happen, I am looking for a wax that has the lowest possible boiling point.

How can I lower the boiling point of a given wax (paraffin wax for instance since it's the cheapest and easiest to buy) by adding other substances inside ? One can easily find on the internet how to increase the BP (by adding stearin for instance), but not the reverse.

Ideally the additional substance should not be added in too great proportion, since that would lower the wax composition and thus the amount of wax vapor emitted.


texts: What is the chemical reaction between caustic soda + salt + magnet wire?

texts:
Intro

Magnet wire(or enameled copper wire) is round insulated Copper wire.
The insulation is generally made of polymer film and this insulating films generally use polyvinyl formal(Formvar), polyurethane, polyamide...

Questions

I'm trying to find the easiest way to strip magnet wire (get the insulation off of magnet wire). I found this video but I want to know that:

What is the chemical equation of this reaction?

$\ce{NaOH + NaCl + Cu + Formvar -> ?}$

As you can see on the video, a gas is coming out.

What is the this gas? Is it dangerous?
Is copper affected by this reaction?


texts: Why are the atomic radii of iron, cobalt, nickel, and copper almost the same?

texts:
We have to select the set of elements which will have almost the same atomic radii:

$\ce{O, S, Se, Te}$
$\ce{Li, Be, B, C}$
$\ce{Fe, Co, Ni, Cu}$

I googled the atomic radii of the third set and found them to be extremely close to one another: all of them are nearly $\pu{125 pm}$ (according to empirical data from Wikipedia). Is there a specific reason for this, or is it just a coincidence?


texts: Number of octahedral and tetrahedral voids present in a HCP structure

texts:
The given image depicts the tetrahedral and octahedral voids in HCP structure.

For the tetrahedral part

I figured out that there would be 6 tetrahedral voids in total.

  My visualisation: In the image, 3 inverted and 3 upright tetrahedron can be formed. Is this correct?

For the octahedral part

It is hard to visualise the octahedrons for an atom. And so, I can't figure out the number of octahedral voids in HCP.

  Also, I want to calculate how much part of the octahedron (see figure) is in each HCP structure.

Finally, the image shows only one octahedron. Can you help me in visualising the other octahedrons?


texts: Why are low spin tetrahedral complexes so rare?

texts:
As I was going through Concise Inorganic Chemistry by J. D. Lee, I  realised that there are simply no low spin tetrahedral complexes mentioned in the book. Is there any specific condition required for the formation of such a complex?
Usually low-spin complexes are in $\mathrm{dsp^2}$ electronic configuration. But can this kind of orbital form a tetrahedral geometry? Because usually tetrahedron is usually synonymous to $\mathrm{sp^3}$.


texts:
Question

  A balloon of diameter $\pu{2 m}$ has a volume of $\pu{4190 dm^3}.$
  It floats since it is given an up thrust equal to the mass of air it displaces.

  (Given: average $M_\mathrm{r}$ of air = 29.
  Under conditions of inflation, $\pu{1 mol}$ of $\ce{H2}$ occupies a volume of $\pu{23 dm^3}).$

  Find mass of $\ce{H2}$ in balloon.

My method

$$\text{Amount of}~\ce{H2} = \frac{\pu{4190 dm^3}}{\pu{23 dm3 mol-1}} = \pu{182.2 mol}$$
$$\text{Mass of}~\ce{H2}~\text{in balloon} = \pu{182.2 mol} × \pu{2 g mol-1} = \pu{364.4 g}$$

Correct answer: $\pu{182.2 g}$.

I don't understand why the answer is 182.2g


texts: How do I know if concentration of Ammonia affected my absorbency measurements?

texts:
This is for determination of copper in a penny Lab. After making standard solutions we made a solution with a penny, dissolving it in nitric acid and adding ammonium hydroxide to form a more absorbtive copper complex. We didn't control the amount of ammonium hydroxide used in our samples.
How can I test whether or not it has an effect, specifically?


texts: Preparing polyurethane with IPDI (Isophorone Diisocyanate)

texts:
I am trying to prepare a polyurethane using hydroxy-terminated polybutadiene (a polyol) and IPDI (a diisocyanate) as the curing agent. I intend to use DBTDL as a catalyst. I read that both IPDI and DBTDL are very toxic and dangerous to use. Being a non-chemistry student, I do not have a lot of experience dealing with chemicals. Could someone point to finer details involved in the process (things like the PPE used, whether the reaction needs to be done in a fumehood, etc.)?

Thanks.


texts: How to calculate the Gibbs energy for the vaporisation of solid ammonia?

texts:
Given that $P_{\ce{NH3}}=\mathrm{10~atm}$ at $298\ \mathrm K$, calculate the $\Delta G^\circ$ of the reaction $$\ce{NH3(s) <=> NH3(g)}$$

I'll begin solving the problem...

I'm using the formula $$\Delta G=\Delta G^\circ+RT\ln Q.$$ The vaporisation of $\ce{NH3}$ is an equilibrium so  $\Delta G=0$ and $Q=K_c$ . Also $K_c=\left[\ce{NH3}\right]$. So $\Delta G^\circ=-RT\ln K_c$.

How do I continue? Is it $K_c=K_p=10$ or $K_c=K_p/\left(RT\right)$?


texts: What is the correct way to transfer large volumes of chemicals?

texts:
I am an engineer starting a film developing and processing lab in my house for personal use. I am currently using a bathroom, and am concerned about contaminating my chemical process and the bathroom using what seem to be accepted practices in developing labs.

Many developing chemicals (e.g. Kodak D-76) come in exact quantities to mix 1 gallon of stock solution. I will mostly be using quantities 500 mL or less, though certain chemicals will be larger arbitrary volumes.

What methods/equipment are used for transferring large volumes?


texts:
If we add an ionic solute to water, will the specific heat of the water be increased or decreased?

I understand that the specific heat is a measure of how much energy we must add to water for the average kinetic energy of the water molecules to go up by a certain unit.

I also understand that hydrogen bonding is what limits the kinetic energy of the water molecules. This accounts for water's high specific heat.

However, when adding an ionic solute to water, such as $\ce{KI}$, we disrupt the hydrogen bonding. So we may expect the specific heat of a water solution to be lower than that of pure water.

On the other hand, there are ion-dipole interactions created, correct? These will act to at least partially counteract the specific heat depression, correct?


texts: Decomposition products of hexaurea-chromic-chloride-trihydrate

texts:
I am sitting over a TG diagram of the decomposition steps of hexaurea-chromic-chloride-trihydrate ($\ce{[Cr(CO(NH2)2)6]Cl3 \cdot 3 H2O}$) and cannot really make sense of the products it might decompose into.

It is clear that water leaves first (-3.5%), and the next step might be (with a wide error margin) fumes of $\ce{CO2}$, $\ce{H2O}$ and $\ce{2 NH3}$. What is left is then $\ce{[Cr(CO(NH2)2)5]Cl3}$.

I have not found any resources on what might happen further - the four urea ligands could decompose into $$\ce{4 CO} + \ce{5 NH3} + \ce{3/2 N2} + \ce{1/2 H}$$ and I am left with $\ce{CrCl3}$ and urea, but those steps show up last (17.9% + 17.3% + 5.4% = 40.6%), leaving the 15.5% in the middle unexplained.

What other decomposition could take place after water and two urea ligands are gone? Is there a way to figure that out other than by guessing or experiment?


texts: I'm designing an aircraft, and certain sections need to hold under a lot of stress. I know that it is the ways the metal crystallizes that effects the mallebility, but does the distance between the atoms/ crystal arrangement also effect malleability?


texts: Molecular orbital diagram for nitrogen monoxide, the nitrosyl cation and the nitrosyl anion

texts:
As I understand it, all of them should have same order of energy of molecular orbitals as a model for $\ce{NO}$ should withstand ionization and adding an electron.

JD Lee Pg 109 shows the same diagram for $\ce{NO}$ as the one quoted in here. I couldn't find $\ce{NO+}$ except in here, where $\sigma_{2p_z}$ has a higher energy than $\pi_{2p_x}$ and $\pi_{2p_y}$.

If it is correct, then, there is $s$-$p$ mixing in $\ce{NO+}$ but not in $\ce{NO}$?


texts:
I am doing a physics experiment in which it is required to etch the outermost glass layer from a coverslip (regular lab apparatus). What concentration of NaOH should be dissolved in water, and how long should the coverslip be placed in the base?
Any idea or information that can help me figure out myself is welcome.


texts: Why are equations of state for a non-ideal gas so elusive?

texts:
The ideal gas equation (daresay "law") is a fascinating combination of the work of dozens of scientists over a long period of time.

I encountered Van der Waals interpretation for non-ideal gases early on, and it was always somewhat in a "closed-form"
$$\left( p + \frac{n^2a}{V^2} \right)(V - nb) = nRT$$

with $a$ being a measure of the charge interactions between the particles and $b$ being a measure of the volume interactions.

Understandably, this equation is only still around for historical purposes, as it is largely inaccurate.

Fast-forwarding to the 1990s, Wikipedia has a listing of one of the more current manifestations (of Elliott, Suresh, and Donohue):

$$\frac{p V_\mathrm{m}}{RT} = Z = 1 + Z^{\mathrm{rep}} + Z^{\mathrm{att}}$$

where the repulsive and attractive forces between the molecules are proportional to a shape number ($c = 1$ for spherical molecules, a quadratic for others) and reduced number density, which is a function of Boltzmann's constant, etc (point being, a lot of "fudge factors" and approximations are getting thrown into the mix).

Rather than seeking an explanation of all of this, I am wondering whether a more "closed form" solution lies at the end of the tunnel, or whether the approximations brought forth in the more modern models will have to suffice?


texts: Amphoterism and the Metal and Non-Metal Oxides/Hydroxides. Why does amphoterism occur in these?

texts:
I am having trouble understanding why Beryllium Oxide and Aluminum Oxide are amphoteric. Also, while they are not oxides, Aluminum and Beryllium Chloride as well.

Most of the things I have been taught or have read is that the partial covalent character of the bonds in these compounds is what allows them to be amphoteric. By not having to behave as strictly ionic allows them to be either an acid or a base depending on what type of solution they are in and what they are being reacted with. Is this correct?  If so, why does the slight change in bonding contribute to the amphoteric behavior?

Covalent bonding seems to be a common theme in amphoteric substances. Why is this so?

I've been staring at reaction of Beryllium Hydroxide and Aluminum Oxide and can't grasp why they alternate between acid and base behavior, depending on what they are reacted with, and how this phenomenon is related to the electron arrangement and bonding. Can someone elucidate this in some detail?


texts: The amount of citric acid for golden syrup

texts: I want to make a good golden syrup at home. I've tried it few times, but all of them were bad. I think the problem was the amount of citric acid. I want to know how to calculate the amount of citric acid which is needed to make golden syrup from 1 kg of table sugar and 500 ml of water. And also: how much time does take all of the sucrose molecules to break down into glucose and fructose?


texts: Chemical Equation: Sulfuric acid and powdered sodium carbonate

texts:
I was asked to write a balanced chemical equation for the reaction between sulfuric acid and sodium carbonate. The balanced equation isn't the problem. The question asks to also show all the state symbols.

All the equations I find online have sodium carbonate as a solution, not a solid. I'm also aware there are two forms of the balanced equation:
$$\ce{H2SO4(aq) + Na2CO3(s) -> H2CO3 + Na2SO4 -> H2O + CO2 + Na2SO4}$$
So do I say the sodium sulfate is a solid or in solution?


texts: Chemical potential and it's implications in an open system

texts:
Take the fundamental equation for the Gibbs free energy of a system:

$$dG=VdP-SdT+\sum_i\mu_idn_i$$

Thus, the chemical potential can be defined in terms of the Gibbs free energy as follows:

$$\mu_i=(\frac{\partial G}{\partial n_i})_{P,T}$$

Now, assuming that the chemical potential is positive (i'm not sure if that is always true) if I add $dn$ of component $i$, $dG>0$ which means (given that the Gibbs free energy is the capacity of a system to do non PV work) I have enabled the system to do more work. Consequently, I have done work on the system by adding more substance to it because i think I have increased it's potential - like raising a mass to a greater height.

It makes sense to me that adding a substance to a system would increase it's capacity to do work however, it doesn't make sense to me that work must be done to add moles of a substance. It's more clear when I think about the converse...

If I remove a small amount of the substance I reduce it's capacity for work and the system must therefore give out energy. This is confusing to me because surely i'd have to do work to remove a portion of a substance from a system - breaking the intramolecular forces and so on. However, for an ideal gas, there aren't any intramolecular interactions so unless the chemical potential for an ideal gas is zero (which I assume it's not) I must be missing something?


texts:
Why is it that oxidizers (specifically $\ce{KClO3}$) are at risk of causing a fire when they come into contact with the rubber stopper used to contain them in their container, but can be slowly heated if they do not contact the rubber stopper?

Essentially, why is it that oxidizers are incompatible with rubber?


texts: is there any mnemonic for the AXE method?

texts: Is there any mnemonic that helps remembering the names of the different geometries (Shapes) that we obtain from applying the AXE method ?


texts: Performing an SN1 reaction in a polar aprotic solvent

texts:
Straightforward question
What would be the outcome of having an SN1 reaction carried out in a polar aprotic solvent? I have found this question approached scarcely and with unsatisfactory answers.
What I know so far
I know the SN1 reaction is carried out in a polar protic solvent since it helps stabilize the carbocation that gets formed (thanks to the lone pairs adjacent to the electronegative atoms of the solvent itself) and also the leaving group (stabilized by hydrogen bonding).

Also, many such reactions are performed as solvolysis and it is preferred - and is much more efficient - to have the solvent act as the nucleophile when this is possible. Based on this we can ascertain the fact that a polar protic solvent would be the best choice for such a reaction and its polar aprotic homologue would not do as well.

All of the reaction rates comparisons I have seen so far take into account a polar protic solvent and a nonpolar one. But what about the protic-aprotic dichotomy?
Final note
However, my question is - can we not use a polar aprotic solvent at all? I have no problem imagining it would perform in a less efficient manner. However, stabilization is not completely absent - at least it has the capacity to stabilize the carbocation. Would the sheer lack of stabilization of the leaving group (and of the nucleophile even though many SN1 reactions do not use charged nucleophiles) render this kind of solvent completely useless for this reaction? Or would it work to some extent?


texts:
If $\ce{C2O4}$ is very unstable no matter the configuration(that is the structure based on the bonds) and especially unstable in the form that has an oxyanion and a carbocation than how come other carbon oxides are much more stable despite the charges like $\ce{CO}$ for instance.

There are 2 possible structures with octets for this. They are

1) $\ce{C=O}$ with the carbon having 1 lone pair and the oxygen having 2 lone pairs. No charges here.

2) $\ce{C≡O}$ with $\ce{C}$ having 1 lone pair and $\ce{O}$ having 1 lone pair making the oxygen positive and the carbon negative.

This one is an important but very unstable structure.

Why is it so unstable? It is because while carbon isn't so determining as to what charge it prefers, Oxygen is and it really hates being positive because it wants to be either neutral or negative since it is more electronegative than everything else except fluorine. This is why $\ce{H3O+}$ isn't really $\ce{H3O+}$ but rather an ion in a complex of ions is because of how oxygen hates being positive.

So why are other carbon oxides more stable than $\ce{C2O4}$ when they too have very unstable structures like $\ce{CO2}$ having as a resonance structure a single bond to 1 oxygen making it negative, a triple bond to the other making it positive, and the carbon staying neutral? And if every carbon oxide is either unstable no matter the structure or has unstable resonance structures than why do carbon oxides with just carbon and oxygen exist?

And would adding hydrogens to a carbon oxide make the carbon oxide even more stable? By this I mean that with the fact that carbon oxides tend to be unstable and hydrocarbons tend to be stable would a carbon oxide with hydrogens added to it be less stable than a hydrocarbon but more stable than a carbon oxide?

Is this how come glucose is so stable and 6 $\ce{CO}$s bonded together would be extremely unstable just like $\ce{C2O4}$ is?

Sorry if it is too many questions but it is all about 1 thing, Carbon Oxides.


texts:
Sometimes in certain electric circuits (such as in voltaic cells) ions are moved around as well as electrons.

I have a basic understand of what materials (mostly metals) conduct electrons well but what materials conduct ions well? What makes ionic conduction fast or slow?

I have read that molten salts are good ionic conductors and that seems sensible to me because all particles in a molten salt are charge carriers and there is nothing to get in the way of carrying charge. But I don't know much more than that such as what sorts of molten salts would be the best ionic conductors.


texts: Calculating standard enthalpy of reaction, which reactant to choose for the amount of substance

texts:
For example, this reaction: $$\ce{2NaOH + H2SO4 -> Na2SO4 + H2O}$$

Suppose both concentrations are $1\ \mathrm{mol\ l^{-1}}$ (standard condition). There is $0.02\ \mathrm{mol}$ ($20\ \mathrm{cm^3}$) of $\ce{NaOH}$, and $0.01\ \mathrm{mol}$ ($10\ \mathrm{cm^3}$) of $\ce{H2SO4}$. So neither reactant is the limiting reactant.

Well, I know one way is to find the standard enthalpy of formation of all components and subtract the ones of products from reactants'. My question is if only experiment data is given.

For temperature change of $\Delta T$,
$\Delta H = mc\Delta T = (0.03)\times(4200)\times\Delta T$,
where $m$ is the mass of the solution. Since the density should be similar to water $1000\ \mathrm{kg\ m^{-3}}$,
$20\ \mathrm{cm^3} + 10\ \mathrm{cm^3} = 30\ \mathrm{cm^3} = 0.00003\ \mathrm{m^3}$
which translates to $0.03\ \mathrm{kg}$. $c$ is just the specific heat capacity of water, it was assumed that the specific heat capacity of the mixture is more or less the same as the water's.

Now the standard one $\Delta_\mathrm{r}H^\circ$ requires division by the amount of substance, but which one – $0.02\ \mathrm{mol}$ or $0.01\ \mathrm{mol}$? What if $\ce{NaOH}$ is $0.021\ \mathrm{mol}$? Or $\ce{H2SO4}$ is $0.011\ \mathrm{mol}$?


texts: Ratio of rate of diffusion of two gases under constant temperature and pressure

texts:
I'm consulting one of higher classes books to study chemistry. I had been studying Graham's Law and question related to rate of diffusion. I came across a question[1] which says:

  Calculate the ratio of diffusion of $\ce{SO2}$ and $\ce{CO2}$ under constant temperature and pressure.

The question mentioned the mass of elements as following:   $\ce{S}=32$, $\ce{O}=16$, $\ce{C}=12$.

My solution of the question:

Molecular mass of $\ce{SO2}=32+32=64$

Molecular mass of $\ce{CO2}=12+32=44$

$$\frac{\textrm{Rate of diff. of}\ \ce{SO2}}{\textrm{Rate of diff. of}\  \ce{CO2}} = \sqrt{\frac{44}{64}} = \frac{\sqrt{11}}{4} $$

But the book has a different answer at the back, where it says $1:2$. I rechecked and performed all the maths again, but still cannot find this answer. Is the book incorrect, or have I made a mistake? If the latter, please help me find it.

D. N. Singh: Basic Concepts of Inorganic Chemistry, 2nd Edition.
Pearson India, December 2011. ISBN: 9788131768617
URL of publisher


texts: Does any molecule containing only ionic bonds exist as a gas in room temperature? In the case of carbon dioxide, it is a covalent molecule which is a gas at rtp. Does the same apply for ionic compounds?


texts: Water Droplet permeability through Graphene Oxide

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TL;DR: The above image is an over simplified model to my question begging to know whether the permeation behavior exhibited by water droplets through graphene oxide is the top image or the bottom.

I couldn't find information about this anywhere:

It has been confirmed that water vapor and pools of liquid water can pass through graphene oxide films (prepared for stability in water on aluminium substrates) assuming the interlayer distances and quantity of layers are appropriate for optimal passage.

However, I do not know whether or not a droplet of water (placed on one side of graphene oxide) will permeate through the graphene oxide film and emerge intact on the other side of the film. I could simply confirm this by spraying water onto graphene oxide but I cannot make a legitimate film on my own just yet is why I ask.
Basically, stated differently, I don't want to end up spraying graphene oxide with water droplets on one side and end up with a stream of water on the other side; they are to ideally remain as droplets.

The question is very simple but also very important in determining to what extent G.O. can be utilized. There are also different studies that conclude different permeation mechanisms for water through G.O. so I can't even reason the answer out on my own. Quite maddening.

Thank you all and sorry for the pure info. extraction but it's for the greater good!

EDIT1: Oh, the preferred droplet max diameter would be 100 micrometers.

EDIT2: Thanks for the reads; I'll try and find the best method for making graphene alumina oxide to try and find the answer on my own. If anyone can point me to the best method meanwhile, that would also be great. Thanks again


texts:
When we calculate the electrons and orbital numbers in $\ce{CH4}$ $sp^3$ hybridization we have taken 3 electrons from $2p$ of $\ce{C}$ and 1 electron from $2s$ of $\ce{C}$ but in $\ce{C2H4}$ we have $2sp^2$ (2 electrons from $2p$ and 1 from $2s$).

Why do $\ce{C}$'s atomic orbitals make $2sp^2$ in $\ce{C2H4}$ and $sp^3$ in $\ce{CH4}$?
How we associate the numbers of electrons from $2p$ and $2s$?


texts: Ethane and ethene: which is easier to burn? Which one burns hotter? Why?

texts:
Anything that burns "easy", has a low activation energy ($E_\mathrm a$) for the burning process. Anything that burns hotter, will have a lesser enthalpy and thus, will have a more aggressive exothermic reaction.

Ethane is a molecule with two carbon atoms and 6 hydrogen atoms; all bonded with covalent single bonds. Ethene has the same number of carbons, but 4 hydrogen atoms; the bond between carbon atoms, in this one, is a double bond.

If you had to choose a fuel, and heat was your prior factor, which one would you have chosen? I imagined that for this, the activation energy and the enthalpy comparison could lead to an answer. I could easily have looked both $E_\mathrm a$ and enthalpies up, but I didn't.

Why and how do enthalpy and $E_\mathrm a$ change when two single bonds and two H atoms are replaced with a double bond?


texts: Are there terms for ions of chlorine other than chloride?

texts:
An ion of chlorine with a charge of −1 is called a chloride ion/anion.
Are there terms for other ions of chlorine, for example, $\ce{Cl+}$ or $\ce{Cl^2-}?$


texts: Why does boron trifluoride form boron tetrafluoride ion instead of boron pentafluoride ion?

texts:
From ChemWiki by UC Davis:

  As a side note, it is important to note that $\ce{BF3}$ frequently bonds with a $\ce{F-}$ ion in order to form $\ce{BF4-}$ rather than staying as $\ce{BF3}$. This structure completes boron's octet and it is more common in nature.

Wait, what? Boron has three electrons. Bonding with four fluoride ions gives it four electrons — these are covalent bonds (shared electrons). That makes for a grand total of 7 valence electrons. Did the author mean $\ce{BF_5^2-}$?


texts: Literature values for NaCl Eutectic - Calculating the eutectic

texts:
For the NaCl eutectic I've seen two values widely used:

23.3wt% NaCl - James G. Speight: Lange's Handbook of Chemistry 2017)

5.1 M NaCl (Marion + Kargel 2008 - Cold Aqueous Planetary Geochemistry with FREZCHEM)

both of which are at about -21C.

Am I being silly - these values aren't the same (they're both at atmospheric pressure)?

Is my maths right?
[23.3wt%=3.99M and 5.1M= 29.8wt%]


texts: Which class of polymerization reactions reaches high conversion under one second?

texts: Are there polymerization reactions that can reach high conversion very fast, say under 1 s? i.e. to polymerize "immediately"?


texts: Mass of salt required to make a 1.2 g/ml solution

texts:
I would like to make an NaCl and water solution with a density of 1.2 g/ml. How would you calculate the grams of NaCl required to make a 1000 ml solution?

I have used density of mixture = (mass NaCl + mass H2O)/1000 ml and solved for the mass of NaCl. However, the resulting mass does not give a density of 1.2 g/ml in practice (and in fact does not dissolve) so is there another way of calculating this? (at room temperature (~21 °C))


texts: Reactivity of group 13 elements with nitrogen

texts:
Do all group 13 elements react with nitrogen to form nitrides of form $\ce{MN}?$
J.D. Lee's Inorganic chemistry book mentions the following:

Aluminium burns in dinitrogen at high temperatures forming $\ce{AlN}.$ The other elements do not react.

However, a reaction of boron with nitrogen is mentioned elsewhere:
$$\ce{2B + N2 -> 2BN}$$
I'm assuming these boron and aluminium do react. Do gallium, indium and thallium react with nitrogen as well?
Please post your answer mentioning a reliable reference or source.