texts:
Liquid soap that sits in metal pump handles turns blue after a week or so, as in this photo comparing the soap in its initial clear state and then after pumping from the dispenser.

The pumps are presumably brass with either nickel or chrome electroplating on the exterior.  Can't say for sure whether or to what degree the interior where the soap makes contact is plated.  They have been in use for years.

The ingredients of this particular soap are:

water
sodium laureth sulfate
cocamidopropyl betaine
decyl glucoside
sodium chloride
"fragrance"
DMDM hydantoin
polyquaternium-7
tetrasodium EDTA
citric acid
sodium sulfate
PEG-120 methyl glucose dioleate
PEG-7 glyceryl cocoate
poloxamer 124
D&C red #33
FD&C blue #1


texts: Can other substances be dissolved in a saturated solution?

texts: If I have a liter of water fully saturated with sucrose would it be possible to dissolve something like salt or any other substance in the water? Or when the solution is saturated, is it impossible to dissolve another solute in it?


texts: Which base accepts the proton abstracted from water in propyne hydration?

texts:
I am enrolled in Organic Chemistry 1 at a junior college and I need some assistance in understanding this mechanism. I have previously taken chemistry in high school with no problems, this would be my first time not comprehending the subject. We are covering the hydration of alkynes.

In the general mechanism, the triple bond of propyne attacks $\ce{H2SO4}$. The hydrogen, the electrophile, goes to the least substituted carbon. We now have a carbocation so water comes in as a nucleophile and attacks. But, now we have a positive charge on the oxygen, so a base de-protonates the molecule. My question is, what is this base?

After the base attacks the lone pairs from oxygen travels down to the carbon and the pi bond then attacks $\ce{H3O+}$. This is the keto-enol tautomerizatiom. My second question is, where did we get this $\ce{H3O+}$? Our list of reagents is $\ce{H2O, H2SO4}$ and $\ce{HgSO4}$. We get a product called acetone. I'm just very fuzzy on the in-between steps.


texts: A sample of tap water is found to be 0.025 M in Ca2+. If 105 mg of Na2SO4 is added to 100.0 mL of the tap water, will any CaSO4 precipitate?

texts:
Given:

Ksp of CaSO4 is 7.10*10^-5
Molar mass of Na2SO4 is 142.04g/mol

My Attempt:

Step 1 - figure out molar solubility of CaSO4

√7.10*10^-5 = 8.43*10^-3M

Step 2 - convert Na2SO4 from mass to moles

105mg = 0.105g
0.105/142.04 = 7.39*10^-4 mol

Step 3 - figure out moles of CaSO4 produced

Since we need 1 mol of Ca2+ & 1 mol of Na2SO4 to form 1 mol of CaSO4
And we have less Na2SO4 than Ca2+

CaSO4 produced = 7.39*10^-4 mol

Step 4 - figure out molarity of CaSO4

7.39*10^-4mol / 100ml = 7.39*10^-3 / L = 7.39*10^-3M

Step 5 - figure out if any CaSO4 precipitates

8.43*10^-3M > 7.39*10^-3M
Therefore NO CaSO4 precipitates

The answer in the book is a Yes, can anyone please explain to me where I have gone wrong?
Thanks!


texts:
I am watching the Stoke vs Swansea game, & to be honest, it's pretty boring. So much so, that I've started to wonder why it is that my beer has turned into a slushy after being taken out of the freezer.

I bought it this morning, it wasn't very cold, so just before the game I put it in the freezer to achieve optimal freshness. Started off pretty well, but rather than getting warmer as I drink, it's actually continued to freeze.

I am in France.

The windows are open.

It's 22 degrees Celsius.

I have attached a pic of the beer in question.

Have I discovered the holy grail of beer chilling?


texts: If we heat BDC with water then phenol is formed. I was wondering what would happen if we heated dry benzenediazonium  chloride. I know that on heating benzenediazonium fluoroborate we obtain fluorobenzene but then it (benzenediazonium  fluoroborate) is insoluble in H2O so there is no confusion over there. On the other hand BDC can be obtained in both forms.


texts: Can you concentrate alcohol by evaporating the aqueous solution at room temp and collecting on a cold surface?

texts:
I have a bowl containing cheap wine and an immersible fish tank heater. The heater warms the wine to 30 deg C. The bowl is located in a large closed bucket, where it sits on a support. The bucket is sited out of doors in winter when the air temperature is Ca 1 deg C. Evaporation occurs and the vapour condenses on the inner surface of the bucket. Droplets of condensate run down and form a pool of liquid on the floor of the bucket.

Question: what can be predicted about the composition of the condensate?

Question #2 What effect is achieved by raising or lowering the temperature of the wine on the composition of the condensate. In plain language what temperature of the wine will give me the highest concentration of alcohol in the condensate? How can the strength of the alcohol be measured?

Question #3 What is the effect of different air temperatures outside of the bucket (on the composition of the condensate)?

Question #4 Why is this method not commonly used to concentrate alcohol?


texts: What happened to the authors of 'Modern Quantum Chemistry"?

texts:
This is kind of a silly question, but my google-fu has failed me, and I can think of no better place to ask it:

What ever happened to the authors of the classic "Modern Quantum Chemistry", Attila Szabo and Neil S. Ostlund? I notice that they were faculty at IU and University of Arkansas, respectively, but see no mention of their retirement or anything else. Are they still with us today? If so, what are they up to?


texts: Why does chemisorption increase with rise in temperature, even though it is an exothermic process?

texts:
Chemisorption is exothermic process, but still it increases with increase in temperature. Why?

I know that there needs to be a minimum activation energy to be achieved in order to initiate chemisorption. Also physiosorption can change to chemisorption in some cases on merely rising the temperature.

But why does it increase with an increase in temperature? How is this related to Le Chatelier's principle?


texts: Why is the spectroscopic entropy of carbon monooxide higher than that of nitrogen?

texts:
While solving a question set, I found a question with this data table (at $\pu{298K}$):
$$
\begin{array}{lrrr}
\hline
\text{Substance} & T_\mathrm b/\pu{K} & S^⦵_\mathrm{cal}/R & S^⦵_\mathrm{spec}/R \\
\hline
\text{Nitrogen} & 77.35 & 18.3 & 18.30 \\
\text{Carbon monoxide} & 81.61 & 18.6 & 19.22 \\
\hline
\end{array}
$$
The first part of the question asked why $\ce{CO}$ has higher $S_\mathrm{spec}$ (spectroscopic entropy) than $S_\mathrm{cal}$ (calorimetric entropy). I know that this is due to the residual entropy of $\ce{CO}$.$^*$
However, the next part of the question asked why the value of spectroscopic entropy of $\ce{CO}$ is larger than that of $\ce{N2}$. The question supplied the information that the rotational reduced temperature ($\theta_T$) was same for both molecules (I think that means the rotational partition function $q_\mathrm{rot}$ will be same for both); and that the contribution to entropy from the vibrational modes to entropy is negligible in both cases.
Now the spectroscopic entropy can be written in terms of the contribution of each degree of freedom:
$$S_\mathrm{spec}=S_\mathrm{trs}+S_\mathrm{rot}+S_\mathrm{vib}+S_\mathrm{elec}$$
The translational entropy contribution depends on the translational partition function $q_\mathrm{trs}$ , which depends on the mass of the molecule. $\ce{CO}$ and $\ce{N2}$ has almost the same mass (28.01 u), so I don't think there would be any difference in $S_\mathrm{trs}$.  The rotational and vibrational terms are assumed to be same in the question. The electronic term should also be zero in both cases, as the electronic partition function would be 1 for both. (I think the excited states are all inaccessible at room temperature).
So where does the difference in the calculated entropy come from?
I feel like the answer is something simple that I have missed.
$^*$ For the concept to discern calorimetric entropy from spectroscopic entropy, see for example this Chemistry LibreText; an literature example e.g., in  1958JAmChemSoc1054.


texts:
Everyone says that our left and right hand are mirror images of each other and are non-superimposable, unlike a sphere whose mirror image is exactly superimposable. But shouldn't our left and right hand be considered achiral?
If I move my hands in front of me such that palm of both the hands face towards me and move my say left hand horizontally such that it can be superimposed on the right hand clearly they can't be because the thumbs point in opposite directions.

But if I rotate my left hand by 180 degrees so that now the palm of my left hand faces away from me then both the left and right hand are superimposable. So shouldn't they be achiral? I know there are two more similar questions akin to this but none of the answers answer my simple question.


texts: How does High Frequency water electrolysis work?

texts: I have read that combining the DC current with a high frequency AC current, the electrolysis of water speeds up. Is this true? In that case, how is less energy wasted as heat? Or does it simply catalyze the process?


texts: Why doesn't Boron form Diborane with water?

texts: Why is it that Boron does not form Diborane with water rather than $\ce{B2O3}$?


texts:
In the reaction $\ce{CH_4 + 2O_2->CO_2 + 2H_2O}$ the $\ce{C}$ atom is oxidized. I can clearly see the addition of $\ce{O}$ atoms, however I don't see a change in Oxidation state. In the products, $\ce{C}$ oxidation state (O.S) was +4, and in the reactants, $\ce{C}$ O.S is +4. I believed an oxidation meant an increase in oxidation state.
What am I missing?


texts: Why doesn't laser ablation decompose sample

texts:
I was reading up on LA-ICP-MS and MALDI. All the sources I read for LA-ICP-MS simply say that when the laser hits the sample immediately goes into the gas phase. Why doesn't the laser immediately break fragile molecules?

MALDI makes sense to me. You put the sample in a matrix that absorbs UV really well then hit the matrix-sample mix with a bunch of UV. The matrix explodes essentially, pushing the sample into the gas phase. The key here is that most of the energy of the laser doesn't go into the sample. It goes into the matrix. This is why the sample doesn't break down. LA-ICP-MS doesn't have the matrix to protect the sample so what gives?


texts:
$\hspace{35 mm}$

ATTEMPT:

Since $\ce{Et3N}$ is a weak base and the carbon to which $\ce{Br}$ is attached is tertiary, we can rule out $\mathrm{E2}$ and $\mathrm{S_N2}.$ As we are providing heat, the reaction is likely to go via $\mathrm{E1}$ forming a stable tertiary carbocation.

Now as the base is bulky it will knock out the most easily available $\ce{H}$, giving us the less substituted alkene.

However my text suggests that this reaction proceed via $\mathrm{E2}$ with the base taking a $\ce{H+}$ and knocking off $\mathrm{Br}$ to give the same final product.

In general with amines out of $\mathrm{E1}$ and $\mathrm{E2}$ which reaction is preferred if there is a possibility of stable carbocation formation?


texts: Ab initio method to calculate C-C bond dissociation energy?

texts:
I'm trying to review how to calculate bond dissociation energy for C-C in ethane, a very simple calculation (or should be).

I get the following Hartree energies for SCF 6-31G(p) for methane, ethane, and H2:

ch4_spe            -40.194639920746,
ethane             -79.228125042573,
h2                 -1.126456057886,

I would think that to get the C-C bond dissociation energy, I would simply do (Perl code)

$energies{ethane} - $energies{ch4_spe} * 2 - $energies{h2}

correct?

The reason that I'm asking is that this give an answer of 2.2876 Hartree using NWChem, which converts to 6006 kJ/mol, which is off by about a factor of 17 from the correct value of about 346 kJ/mol.  I know that SCF isn't that accurate, but it shouldn't be this far off. I optimized the bond lengths using Avogadro.

This is the correct method to calculate the C-C bond energy?


texts: Can it be possible to use atmospheric $\ce{CO2}$ in a reaction (or series) with silicon dioxide, both of which are plentiful, to sequester the carbon in a solid and more useful material, silicon carbide?


texts: Thermite reaction beween zinc and iron(II, III) oxide

texts: I have zinc metal and iron oxide in the form of magnetite which I would like to obtain iron metal from. I was wondering if I could use a thermite reaction to create iron and zinc oxide? I would like to know whether such a reaction would occur between these two substances, how violent it is and whether the reaction will sustain itself?


texts:
Why isn't $\ce{CHCl3}$ soluble in water?

Why doesn't $\ce{CHCl3}$ participate in hydrogen bonding in water like $\ce{CH3CN}$ as $\ce{Cl}$ can make the $\ce{C-H}$ bond polar like $\ce{CN}$ does?


texts: Why is the ionic product for water ($K_\text{w}$) temperature dependent? The concentration of $\ce{H+}$ and $\ce{OH-}$ ions in pure water is $[\ce{H+}] = [\ce{OH-}] = 1.0\times 10^{-7}\ \mathrm{mol/l}$ at $25\ \mathrm{^\circ C}$, and therefore the ionic product of water at $25\ \mathrm{^\circ C}$ is $1.0\times 10^{-14}$. Why it is so? What is the effect of temperature on this value?


texts: Cinnamaldehyde listed as (2E)-3-phenylprop-2-enal , but is the first 2 redundant?

texts:
Wikipedia lists the molecule as being named "(2E)-3-phenylprop-2-enal", however it would appear that, as there is only 1 double bond which has a possibility of stereoisomerism, the 2 is redundant.

Would the correct IUPAC name not in fact be E-3-phenylprop-2-enal?


texts: Long-lived, non-lethal radioisotope for fiction

texts: I'm writing something where the characters are looking for someone among a large set of people. They don't know who this person is and they don't know what they're looking for, so their best bet is to look for anything unusual about this person. I already have a method by using which they'll eventually find him, but I want them to muse over possible, reasonable alternatives. One that comes to mind is looking for any radioactive tracer that might have been injected in the subject. However, for this to make sense within the context of the plot, such tracer should be long-lived enough to be detectable at least for years, and safe enough not to appreciably increase the subject's risk of death over short timespans. (If he's more likely to get cancer at age 90, tough luck, but if the tracer will kill him within five, that's not good.) Any ideas?


texts:
I am trying to identify whether the following objects possess planes of symmetry or not, but my answers seem different, from the textbook solutions (Klein Organic Chemistry 2e, Page 220, Question 23). Some of them I am unsure of and would like to make sure I know the proper reasoning for. Can someone please clarify?

(b) The correct response is yes. Is the plane of symmetry I have drawn acceptable?
(c) The correct response is no, but I thought it is possible to have a plane of symmetry like the one I have drawn.
(e) The correct response is yes, which I think I understand. I think this has three planes of symmetry.
(f) The correct response is no, which I agree with. However, it doesn't seem to concur with the response for the follow-up question.

Follow-up: Which image has three planes of symmetry? The correct answer is apparently, (f). My response would have been (e).


texts: What is the Difference between difference between Standard Electrode Potentials and Standard Reduction Potentials?

texts: As the question suggests I am wondering the difference between standard electrode potentials and standard reduction potentials. I know that they are both a measure of the Voltage from certain reactions, and can be used to calculate the feasibility of a reaction - but when do you use which / what is the difference, or are they interchangeable?


texts: Where do the electrons for which RTG's use for the Seeback effect come from?

texts: I know that RTG's use Radioactive Isotope that emit Alpha particles generally (ie. NASA uses Pu 238), I also know that these Alpha particles are consiting of 2 Protons and 2 Neutrons, since the RTG has two thermocouple plates that force the protons and the electrons to the cooler side. I was wondering where the electrons come from? Also I was wondering how exactly does the Seeback effect utilize these positive and negative charges with the junction formed to create the electrical charge.


texts: Deducing orbital degeneracy in geometries apart from octahedral or tetrahedral

texts:
How do you determine the crystal field splitting pattern when given the structure of a complex?

It's quite simple for structures like octahedral or tetrahedral, but I find that the reasoning behind the patterns for the trigonal bipyramidal structure, for example, is somewhat arbitrary.

Continuing the example of a trigonal bipyramidal structure, the $d_{xy}$ and the $d_{x^2-y^2}$ orbitals are supposed to be degenerate, but the $d_{x^2-y^2}$ fully overlaps with one of the ligands on the complex, while the $d_{xy}$ partly overlaps with two, and I don't think we have enough information to assume that the two "parts" add up to one.

Do I just have to accept that this is how it works (as in, is this just a "limitation" of the crystal field theory)? Or is there some aspect that I am missing/misunderstanding?


texts: What is the relationship between the stability constant of a copper (II) electrolyte complex ion and the output voltage Ecell?

texts: As a part of a school investigation I constructed a voltaic cell experiment where for each run I added a different ligands to the copper (II) sulfate half-cell electrolyte in a daniell cell to see if there was a change in the output voltage Ecell. When plotting a graph of this, it seemed that Ecell increased as the stability of the ligand increased (indicated by the stability constant Kc) however I am struggling to explain why. I presume its because the standard potential at the cathode Erhe increases with ligand stability due to greater oxidation.


texts: How does "breathable" siloxane water sealant work?

texts:
(This is an interdisciplinary question, between molecular chemistry, materials science & construction. I think Chemistry SE is the right fit, but please move it if needed.)

Silane/siloxane solutions are applied to porous building materials (e.g. brick or concrete) to repel water. Unlike a solid coating, these sealants are "breathable", allowing water vapor to exit instead of being trapped, which would cause slow structural damage. How does that work, molecularly?

I presume these compounds affect surface tension in some way, reducing the ability of liquid water to permeate, without completely sealing the pores, but I don't understand it.

Optional: also, how does this sealant affects the permeability of other liquids (polar vs non?) and other gases?


texts: Why do some molecules show non-symmetric absorption and emission bands?

texts: I'm looking at a molecule of [Ru(bpy)3]2+ in water and the absorption and emission bands are not symmetrical. I want to know why the mirror image rule doesn't apply here. Is this because of the MLCT, is this something to do with the solvent? Are there more likely to be processes involving non-radiative decay?


texts: Melting points of benzoic and stearic acids

texts:
I wonder, why does benzoic acid have a higher melting point than stearic acid?
Here is the data:
Benzoic acid melting point = 122.3 °C
Stearic acid melting point = 69.3 °C
I do understand that organic acids can bond with both London dispersion forces (van der Waals) and hydrogen bonds (due to the -COOH group). I have also learned that the longer carbon chains, the higher melting point due to the increase of the London dispersion forces.
However, in the case with benzoic acid vs stearic acid, I can't figure out an explanation as to why benzoic acid has a higher melting point. I suspect it is because of the resonance structure in the benzene ring in benzoic acid?


texts: Finding molecular formula with limited information given

texts:
I have recently stumbled upon a question I can't seem to solve :

  Chlorine can also be used to synthesise a bromine-containing oxoanion that is mainly used in continuous or batch dyeing processes. When chlorine is passed through an aqueous solution containing potassium hydroxide and potassium bromide, the bromide ions are oxidised to the bromine-containing oxoanion. Careful addition of aqueous lead nitrate to the resulting solution precipitates 4.17g of $PbCl_2$. When this precipitate is filtered off and the resulting filtrate is evaporated, 0.835g of a white crystalline solid is obtained. The white solid has the following composition by mass : $K$, 23.4%; $Br$, 47.8%; $O$, 28.8%. $\mathbb \ Determine\ the\ formula\ of\ the\ white\ crystalline\ solid.$

I attempted by first finding the empirical formula of the solid using by dividing the percentage compositions by their respective elements' mass number, and ended up getting $KBrO_3$ as the empirical formula, which would make my second step to find $n$, where the molecular formula of the white crystalline solid is $K_nBr_nO_{3n}$. However, how can I go about doing this without being given how many moles of the white crystalline solid was precipitated? I can't seem to construct the equations that could potentially lead me to the mole ratio between $PbCl_2$ and $K_nBr_nO_{3n}$. If possible, can anyone tell me how to get a better grip on forming equations in scenarios such as this? I have been struggling in this topic for a while and this is likely to be one of the key reasons why. Sorry for the lengthy question!


texts: Difference between continuously overlapping p orbitals and conjugated pi bonds

texts: Is there any difference between the phrase "continuously overlapping p-orbitals" and "conjugated pi bonds" when referring to aromatic compounds? I've heard both used and I wasn't sure if they mean the same thing.


texts:
I am aware that the square of the Wavefunction gives the probability density of finding an electron at a particular point in space. I have also heard that it's a complex number but since it's a function I am unsure as to how that could be the case (perhaps someone could please clear that up for me as a sub-question). Moreover, I have seen it described as the amplitude of something but I literally have no idea what is meant by that. However, the crux of the question is what is the Wavefunction itself (i.e not what the square of it is). I have read in the book "Why Chemical Reactions Happen" that it is essentially synonymous with the word/concept: orbital. I have also seen in various places w(x,y,x) or w(r,theta,thi) [where "w" represents the sign for a wavefunction] so, from what I can gather it is a function in three dimensions that represents the shape of a particular orbital where the function of (x,y,z) or (r,theta,thi) would, of course, be different for the s,p,d and f orbitals. However, in the book "Why Chemical Reactions Happen" it goes onto say that wavefunctions of different atoms interfere with each other to form molecular orbitals and the atomic orbitals somehow have a phase?! For my idea of a wavefunction to be correct, the idea of interference of these wavefunctions must be an idea that was thought of to try and rationalize the process of the formation of molecular bonding and anti-bonding orbitals from atomic ones to make it easier to understand and conceptualize. If I am right about the wavefunction being a purely mathematical representation of the space where an electron is likely to reside then the molecular wavefunctions are just as curious in terms of their shape and suchlike as the shapes of the atomic orbitals they came from (i.e nobody really knows why they are that shape but when atoms or molecules are arranged in a particular way, orbitals "just are" that shape). Also the idea of phase seemed to bring my argument down but then I thought that perhaps phase is simply defined as being opposite relative to another part of an orbital if it is the other side of an angular node (I suspect this is wrong but could someone please shed some light on this?)

Going back to when I said - "the molecular wavefunctions are just as curious in terms of their shape and suchlike as the shapes of the atomic orbitals they came from" - I thought this because I found it bizarre that empty orbitals could "interfere" with an orbital from another atom. For example one p orbital is empty yet all three interact with the four hydrogen s orbitals. Unless, the electrons can jump between the the degenerate p orbitals at such a frequency that all can be considered occupied I find it incomprehensible that just a portion of space can interfere with an orbital. As a result, I came to the conclusion that I quoted at the start of the paragraph. Basically meaning that when atoms come together to form molecules the electrons find the lowest possible energy spaces to reside; or in other words, a molecuar orbital / molecular wavefunction forms which is equally as curious as the atomic wavefunctions with their strange shapes.

Any help with this concept would be greatly appreciated - I am off to Oxford university this October and Molecular Orbital Theory is a small part of the suggested reading list before arrival into the first year. Also, on that note, please refrain from heavily mathematical answers because I simply won't understand as I have only done A-level Maths and A-level Chemistry. Thanks.


texts: Why is gaining hydrogen called reduction when gaining electrons is called reduction? Aren't they opposites

texts:
Reduction is gain of hydrogen  (Source)
Reduction is gain of electrons (Source)

Is it because a hydrogen has an electron so gaining hydrogen is technically gaining electrons? But that doesn't seem right as oxygens also have electrons and gaining oxygens is oxidation.
What is confusing me is when we usually talk about hydrogens, its a hydrogen ion. And hydrogen ions and electrons are opposite. I realise this situation is not a hydrogen ion but a full hydrogen, but it's still doing my head in.


texts: Mechanism for oxidation of primary alcohols to carboxylic acids

texts:
My teacher told me that the following is the mechanism for oxidation of primary alcohols to carboxylic acids:

I've searched in books and online and didn't find a similar mechanism. For example, in Wikipedia:

Which is correct?


texts:
In IIT-JAM 2018, There was one question, which one of the following oxides are ionic?
There was one option PbO also. According to the official answer key, PbO isn't ionic.

Although I know this distinction between ionic and covalent isn't defined sharply. But Pb is a metal and Oxygen is a non-metal. So according to me, it should be Ionic. I tried to find on the internet I couldn't able to find out about PbO, although PbO2 is defined in between of ionic and covalent according to this paper. PbO should be more ionic than PbO2 since oxidation state of the Pb is lower, it will be less electronegative.

Even $\ce{PbCl2}$  is considered as Ionic according to many books, where Cl is less electronegative and much bigger in size as compared to O, So At least PbO should have more ionic character than $\ce{PbCl2}$  according to the Fazan's rule.

So should I challenge the official answer key? If yes, then on what basis? Which reference should I send to them?

Iono-Covalent Character of the Metal–Oxygen Bonds in Oxides: A Comparison of Experimental and Theoretical Data


texts: Why does tetrachlorocuprate(II) form in aqueous solution even though water should be the stronger ligand?

texts: In aqueous solution, $\ce{Cu^{2+}}$ forms the $\ce{[Cu(H2O)6]^2+}$ complex. Given that water is a stronger ligand than $\ce{Cl-}$, though, why does why does the  $\ce{[CuCl4]^2-}$ complex form upon addition of chloride ions?


texts: Help understanding this passage on optical activity

texts:
Other than mirror images, compounds having opposite configurations do not necessarily cause opposite directions of optical rotation any more than do compounds of the same configuration necessarily cause the same direction of optical rotation.

I know what optical rotation is and I know what "molecular configuration" means but I still can't understand what I just wrote above.


texts: Is it possible for me to derive Avogadro's number?

texts:
To my understanding the mole is the unit used to translate between mass on the atomic level and mass in the macro level, defined as the number of atoms in $12$ grams of Carbon-$12$, which apparently turns out to be $\pu{6.0221409e23}$ atoms, and this was defined as Avogadro's Number.

How was this number derived? Is it something I can derive myself? If I had $12$ grams of Carbon-$12$, how would I be able to deduce that it had $\pu{6.0221409e23}$ atoms?


texts: In a reaction between an aliphatic primary amine and a ketone, I could expect a ketimine as a product or intermediate. My question regards tautomerization of this intermediate: has tautomerization between the two possible imine structures ever been observed, or is even possible? I tried to search imine tautomerism and transamination, but I can't find what I'm looking for. I imagine this would be a simple experiment to conduct, but I can't find anything in the literature on this.


texts: Can =NH2+ in Arginine's side chain form hydrogen bonding at physiological pH?

texts:
I know that at physiological pH, Arginine will have its $\ce{=NH}$ protonated to $\ce{=NH2+}$. I was wondering if this $\ce{=NH2+}$ can still form a hydrogen bond by being a donor? And does the positive charge on Nitrogen affect the hydrogen bonding's strength? My confusion stems from the definition of hydrogen bonding, which says that hydrogen's electron cloud needs to be withdrawn by a more electronegative atom like $\ce{F, O, N}$ to be partially positive enough to participate. Therefore, I believe that the positively charged N will withdraw electrons from hydrogens more strongly, leading to more partially positively charged hydrogen and eventually stronger H-bonding with another molecule. Could someone please verify this for me?

Moreover, I have seen $\ce{=O}$ and $\ce{=N}$ forming hydrogen bonding by being an acceptor. However, I tried search but did not find any example of $\ce{=NH3+}$ or $\ce{=NH2R+}$ or NHR2+ forming hydrogen bonding as a donor. So can a Nitrogen with a double bond still participate in hydrogen bonding as a donor?


texts: How can an element have two outermost shells incomplete?

texts:
As I read my book, I saw its written that the Transition metals have two outermost shells incomplete.
But , as I had read earlier, that shells are filled in stepwise manner.
So how is this possible?
And why don't the outermost electrons then don't jump in the inner shells?


texts:
Linus Pauling wrote the famous "Nature of the Chemical Bond" which is a Bible of sorts for valence bond theory.

However, VB theory was combined with crystal field theory to form molecular orbital theory, which eventually was condensed into the Hartree–Fock method.

Are there any "Bible" type reference books for these other methods?


texts:
It's been a while since I've dealt with these, but do character tables include all possible symmetry operations?
I am looking at the $D_\mathrm{\infty h}$ point group table and it lists $C_\infty$, $\sigma_\mathrm{v}$, $S_\infty$, $i$, and $C_2$. But doesn't it also have a $\sigma_\mathrm{h}$? Why is this not included?
Am I missing something here?


texts: Why a Li-ion battery, when in storage, is better kept around 85% instead of 100%?

texts:
I discovered that in my laptop settings, I can select an option that is best chosen when the laptop is mainly connected to AC power, and apparently keeps the battery at a lower SOC.
I found this feature also in a Sony smartphone (slightly different operation, it would keep the battery at 90% max during the night, and would fully charge it at dawn) and I found out that's actually good for battery health.
Why is that? What happens inside a battery when it is kept at 100%?


texts: No buffer region in the titration of strong acids or bases?

texts:
So recently I have conducted a acid-base titration experiment. I encountered that there is no buffer region in strong acid-strong base reaction. However, when take a weak acid or base buffer region appears.
WHY THIS IS LIKE THAT? What I mean is there any rational explanation for this?


texts: If you accumulate 100 identical spheres how many will end up on the surface?

texts:
So far I have asked this question in physics, engineering and math sections but have not gotten an answer in three years. If you have 100 identical spheres and group them into A sphere shape, how many will end up on the surface? They can be packed tight or loose in a hexagon pattern or cubicle pattern. They can be symmetrically or evenly spaced. I realize the answer can be off by one or two depending on how you group them, But in general it seems like something that can be answered. Is there a formula that could be applied to any number of spheres? For example what if you have 120 identical spheres, how many will be on the surface then? Imagine an atom with 120 nuclei in the nucleus. Thanks for your help.
EDIT:After seeing some of the responses it reminded me of my thought process a few years ago when I began to think about this. How do you define surface, what type of packing, etc. etc. I too tried the plastic bags and ended up using different colored magnetic balls. Experimenting has worked just fine and I asked the question because I truly thought a simple formula would be available. As for what the surface is I have found another question that actually comes closer to what I'm interested in. No matter how many spheres are accumulated into a spherical shape you can separate them into two categories. Spheres in the (interior) and spheres on the (surface or touching a sphere on the surface). This seems confusing at first but it actually simplifies the surface question by literally filling the gaps.  So really the question is how many spheres are not on the surface or touch a sphere on the Surface? Even still it can be difficult counting spheres when you transfer between hexagonal, cubical or symmetrically spherical shaped. That is why I have hoped for quicker solution.


texts: What is the difference between absolute and relative configuration in stereochemistry?

texts: Can you help me understand the difference between absolute and relative configuration?


texts:
$\ce{2CH4(g) + O2(g) \rightleftharpoons 2CO(g) + 4H2(g)}$

  Equal numbers of moles of $\ce{CH4}$ and $\ce{O2}$ are drawn into a
  sealed container and the system is left until it reaches equilibrium.
  Which of the following relationships pertaining to this particular
  system are true at equilibrium?

  $\ce{[CH4]<[H2]}$
  $\ce{[CH4]>[O2]}$
  $\ce{[H2]>[CO]}$

I know that the equation for $\ce{K_{eq}}$ is

$$\ce{\dfrac{[H2]^4[CO]^2}{[CH4]^2[O2]}}$$

I think that 3. is wrong because if $\ce{CH4}$ and $\ce{O2}$ are equal, then $\ce{H2}$ and $\ce{CO}$ have to be the same. Now I'm confused about 1 and 2. I'm not sure how to distinguish between the two.


texts: What is responsible for the odor of gasoline?

texts:
Gasoline as we know it is a blend of combustible hydrocarbons and has a characteristic odor. The natural gas we use to heat our homes and (for some of us) cook our food has its own odor, except...

Natural gas as piped to our homes consists of methane, which is odorless, plus an odorant so that we can be aware of its presence for safety reasons. So the odor we think of as "gas" isn't the fuel at all, but an odorant.

So this leads to my question: is the familiar odor we attribute to gasoline that of one or more of the components which are the fuel itself (heptane, octane, etc.) or an additive for the purpose of giving it an odor, again for safety reasons?


texts:
I couldn't find which of these is correct and even someone I asked said there's no general covincement on it, but I'm unsure whether he's correct?

I reproduced the second structure a little wrong maybe, but arrangement and bonds are correct(I think there should be no charge on oxygen).


texts: What is the Lewis dot structure for ozone?

texts:
Currently I studying about the Lewis dot structure for different compounds and my textbook says that the Lewis structure for ozone may be drawn as(as shown in the image):

And then it goes on to calculate the formal charges on different oxygen atoms in it(which are shown in figure with $+/-$ signs.) In justification of the structure it says:

  Formal charges help in the selection of the lowest energy structure from a number of possible Lewis structures for a given species. Generally the lowest energy structure is the one with the smallest formal charges on the atoms. The formal charge is a factor based on a pure covalent view of bonding in which electron pairs are shared equally by neighbouring atoms.

Now, my question is why can't the structure  be like this:

Clearly, if this isn't a possible structure then the flaw in my understanding arises because of not understanding the term 'smallest formal charge'(as I found out that the structure I gave has all oxygen atoms with zero formal charge )
Please suggest what does it mean by the smallest formal charge ? Also why energetically the structure isn't stable.
(For now please exclude any discussion about resonance hybrid of the ozone)


texts: How to determine the configuration of C atom bounded to two groups with same configuration?

texts: What is the configuration of the central C atom in the following molecule and how to determine it?


texts: How much additional product forms when small amounts of reactants are added to a reaction at equilibrium?

texts:
I am not able to understand how to determine the exact amount of additional product formed when additional reactant is added to an equilibrium reaction.

For example consider the reaction:

$$\ce{CO2 + H2 <=> CO + H2O}$$

and suppose the number of moles of $\ce{CO2}$, $\ce{H2}$, $\ce{CO}$, and $\ce{H2O}$ at equilibrium are $a$, $b$, $c$, and $d$ respectively. $K=1$ for simplicity.

Now how do I determine the amount $\ce{CO2}$ to be added to double the amount of $\ce{CO}$ produced.

I have tried by writing the equation for the equilibrium constant and keeping the amounts of $\ce{H2}$ and $\ce{H2O}$ constant but it didn't work out.

What I had done is (where $x$ is the new number of moles of equilibrium)

$$K=\frac{c\times d}{a\times b}= \frac{2c\times d}{b\times x}$$

This gives me $x=2a$ but after this I'm not able to proceed any further.


texts: Epoxide ring opening via decarboxylation

texts:
The answer for the above multiple choice problem is option (C), from which I can understand that at some point in the mechanism the molecule must've undergone decarboxylation.

Also, I think the first step should be protonation of the epoxide oxygen. (No other choice, isn't that the most nucleophilic site?)

I'm not able to understand how the ring opening takes place (guessing it is via decarboxylation, but how?)


texts: Why is the shape of $\ce{PCl5}$ trigonal bipyramidal? All the $\ce{Cl}$ atoms must be at equal distances forming a star like shape. However, in the actual shape, the distance between the $\ce{Cl}$ atoms in the equatorial position is less than the ones in the axial position.


texts: In molecular orbital theory bonding of two atoms can be seen as addition or subtraction of the wave functions of these atoms. Addition seems pretty logical and straight-forward - atoms overlap their electron clouds and probability to find an electron in it increases. Subtraction is the thing I don't get. How can the probability to find an electron be negative? Am I missing something?


texts: Symmetry element in the coversion of cyclopent-2-enyl anion to pentadienyl anion?

texts: I'm trying to draw the state correlation diagram for the reaction of cyclopent-2-enyl anion to pentadienyl anion but I don't know which symmetry element is preserved in this reaction. What could it be?


texts: why "amu" is used as a unit in relative atomic mass?

texts: Unified atomic mass unit (amu) is defined as $1/12$ of the mass of a Carbon-12. I want to know is this amu equal to $\pu{1.99e-23 g}$ and why do we use amu which is $1/12$ the mass of carbon? Why use "amu"?


texts: For the reaction $\ce{SF4 + F2 -> SF6}$, since oxidation state of $\ce{S}$ increased from +4 in $\ce{SF4}$ to +6 in $\ce{SF6}$, can $\ce{F2}$ be referred to as the oxidizing agent?


texts:
Why do defects in crystal lattices of various molecules and compound occur ?
Is it due to the continuous contact or it arises due to impurities and human error during the formation?


texts: Calculating the ionic strength for an aqueous solution containing potassium ferricyanide and sodium sulfate

texts:
I have the $100$ microM of K$_3$Fe(CN)$_6$ is dissolved in water and the following data:
$$\begin{array}{c|c}
\text{Experiment} & \ce{[Na_2SO_4]}/\pu{M} \\ \hline
\mathrm{A} & 0 \\
\mathrm{B} & 1\cdot10^{-3} \\
\mathrm{C} & 3\cdot10^{-3} \\
\mathrm{D} & 8\cdot10^{-3} \\
\mathrm{E} & 1\cdot10^{-2} \\
\hline
\end{array}$$
I want to calculate the ionic strength for each experiment and I know that I should use the equation:
$$I = \frac {1}{2} Σ c_i z_i^2$$
and that it for this case will look like:
$$I = \frac {1}{2} ((1)^2*[\ce{K+}]+(-3)^2\cdot[\ce{Fe(CN)6^3-}] + (1)^2*[\ce{Na+}]+(-2)^2\cdot[\ce{SO4^2-}] )$$
However, when I calculate this for the different experiments, I don't get the number which is in our answer key. There is no calculations in the answers and my answers differ quite much. This is the way I calculate the different ionic strengths:
$$I_{\mathrm{A}} = \frac {1}{2} ((1)^2\cdot(1\cdot10^{-4})+(-3)^2\cdot(1\cdot10^{-4}) + (1)^2\cdot0+(-2)^2\cdot0 ) = 5\cdot 10^{-4}$$
$$I_{\mathrm{B}} = \frac {1}{2} ((1)^2\cdot(1\cdot10^{-4})+(-3)^2\cdot(1\cdot10^{-4}) + (1)^2\cdot(1\cdot10^{-3})+(-2)^2\cdot(1\cdot10^{-3}) ) = 3\cdot10^{-3}$$
$$I_{\mathrm{C}} = \frac {1}{2} ((1)^2\cdot(1\cdot10^{-4})+(-3)^2\cdot(1\cdot10^{-4}) + (1)^2\cdot(3\cdot10^{-3})+(-2)^2\cdot(3\cdot10^{-3}) ) = 8\cdot10^{-3}$$
and so on.
In the answer key $I_{\mathrm{A}}=0.6\cdot10^{-3}$, $I_{\mathrm{B}}=3.6\cdot10^{-3}$ and $I_{\mathrm{C}}=9.6\cdot10^{-3}$. As you can see the difference increases and I don't understand what I am doing wrong. I would truly appreciate if someone could point out my mistakes. Thank you!
EDIT
I am also given this but I don't think they matter for the ionic strength:


texts:
Van der Waals corrected the ideal gas equation for real gases and gave the following equation:

$$\left(p+\frac{an²}{V^2}\right)\left(V-nb\right)=nRT$$

I’m very confused about one aspect of this equation, which is this: why add the pressure term but subtract the volume term?

Edit: If somebody could please just explain the physical significance of the corrected equation and also, exactly what Van der Waals was trying to do by correcting this equation, it would be tremendously helpful for me.


texts:
I am having trouble figuring out how to calculate the detection limit. Here is the question:

You and your friend working in a different lab have been given an unknown water sample that contains potassium.  You are both asked to measure the potassium concentration in the solution (10 replicate measurements).  The methods that you and your friend are using are different.  The results that were obtained are listed below.  Determine:

(a) the concentration, standard deviation and relative standard deviation for the unknown as measured using the two methods (check for outliers!),

(b) calculate the detection limit (3sigma) for each method,

(c) compare the standard deviations and evaluate whether the two averages are significantly different (or not) at the 95% confidence level.

RESULTS:

Standard    Method 1    Method 2
Concentration   Intensity   Intensity
(mg/L)  (nA)    (mV)
0.000   0.624        1.955
0.000   0.488        2.490
0.000   0.522        2.166
0.000   0.355        1.500
5.000   9.245       15.644
10.000  17.069      31.220
15.000  26.200      44.266
20.000  33.881      62.394
25.000  43.826      75.611

Replicate
1       26.544      46.977
2       25.449      49.120
3       21.053      50.998
4       24.353      46.615
5       23.899      49.326
6       24.010      46.666
7       25.554      45.291
8       23.549      42.995
9       26.008      43.678
10      24.404      49.012

So my problem is with part (b). I know the detection limit is calculated with the formula DL = 3sigma/slope and that I can find the slope by calculating Sxy/Sxx but I'm not sure what points I'm supposed to use? What points do I use for the standard deviation (sigma) and for Sxy/Sxx?

I've tried looking at examples in the textbook but nothing was really similar. I also tried searching online, but I couldn't find anything that helped me.


texts: Can an ether be selectively hydrolysed in the presence of an ester?

texts:
What reaction, or protection/deprotection can be used to transform the ether group of a molecule  that also has an ester compound into an alcohol while keeping the  ester unchanged? For example:

The usual way of removing ethers, by acid hydrolysis, would also hydrolyse the ester. Could that preserve the ester under certain conditions?


texts: Different masses for the same element and isotope?

texts:
I am watching this Khan Academy video on mass defect and binding energy, it uses helium-4 as an example to go through the concept. The person finds the predicted mass (protons + neutrons) to be 4.0318274 amu. He also finds that the experimentally measured mass for He-4 to be 4.00150608 amu.

What's baffling me is, where did he find the experimentally measured mass for He-4? I have been searching for the atomic mass of He-4 all over, and every source I found seems to agree that its mass is, in fact, 4.002602 u ± 0.000002 u, that's a 0.001 difference!


texts: What is the canonical reference for studying stereochemistry?

texts:
I am well versed with all the named reactions and all of organic chemistry.  I am quite weak in stereochemistry.

What canonical text can I use to study this topic and connect with other parts of the chemistry?


texts: Number of resonance structures of nitrobenzene

texts:
I was studying about the resonance and here's my doubt:

How many resonating structures are there in nitrobenzene? Is it 5 (as drawn) or is it 4 because first and the last structures are same or is it 3 because second and fourth structures are also same?

In short, do we count fifth structure when we take the number of resonating structures?


texts: How do you get contents of large flask into a smaller separatory funnel?

texts:
Separatory flasks that I use have a ground glass joint, but it is not clear how that joint is to be used. Videos I have seen just show people pouring stuff into the throat of the funnel.

Normally the situation I have is that the solution is in a large flask, maybe a 1000ml flask, and I need to separate a thin layer of the solution that is at the bottom of the flask using a 500ml separatory funnel. The question is how to get the bottom of the flask to the funnel.

Saying "oh just use a bigger funnel" is not a solution, because the flasks, reactors and carboys I have tend to be significantly larger than any normal separatory funnel. For example, if I have a 3000ml reactor or 5 gallon carboy with a solution in it, I am not going to go looking around to spend hundreds of dollars on a gigantic separatory funnel.


texts: Why do isotopes have different chemical reaction rates?

texts:
Isotopes of a given element differ in the rates at which they undergo chemical reaction.

Why is this so? The only explanation I could think of is that the gravitational force on the electrons increases and hence the electrons are better bound to he nucleus. But this force is very negligible.
Is there perhaps another contributing factor?


texts: Subtracting standard electrode potentials

texts:
As far as I'm aware, if we construct a half cell ($\ce{A + e- <=> A-}$) under standard conditions then the standard electrode potential $E^⦵$ is the potential of the $A/A^{+}$ couple wrt. SHE, which doesn't change depending on whether the reaction is an oxidation or reduction in this half cell. This is because potential is a physical, electrostatic concept.

Consequently, the cell EMF is then also defined to be the potential of the cathode subtract that of the anode, $E^⦵_{cell} = E^⦵_{cat} - E^⦵_{an}$. All of the above I have obtained from IUPAC recommendations.

However, some people say that reversing a half equation reverses the sign of $E^⦵$, and then proceed to add the electrode potentials to find the cell EMF. Although this method is algebraically equivalent, it doesn't make any sense - since the electrode potential has nothing to do with the chemical concept of a reaction direction!

The only justification I have seen is that if you write $\Delta G = -nFE^⦵$ for each half equation, and sum them, then the EMF comes out as expected only if we do change the sign. However this seems inherently flawed as well, since although Gibbs free energies are additive, $\Delta G = -nFE^⦵$ only applies to a cell as a whole (because it is derived by considering the energy change if charge flows from one terminal to the other) and is meaningless in the context of a half equation.

Consequently, why is the notion that reversing the half cell equation negates the electrode potential still taught - since to me at least it seems fundamentally incorrect!

Thanks a bunch!


texts: Why are all the phenyl protons in benzyl alcohol equivalent in the ¹H-NMR spectrum?

texts:
Below is a $\ce{^1H}$ Nuclear Magnetic Resonance (NMR) spectrum for benzyl alcohol. The hydrogen in the alcohol group gives rise to a unique signal. The two hydrogens in $\ce{CH2}$ give rise to a unique signal with around twice the signal area. What I don't understand is why all hydrogens in the phenyl group are equivalent. My guess would have been there would be 3 signals from the phenyl ring. One pair of $\ce{H}$ that are equally distant from the methanol, another pair that is also equally distant, and last, a single hydrogen that is the furthest away from the methanol. Clearly this is not the case, and the 5 hydrogen give rise to a single signal only.

Why? What is a good way to think about equivalent and non-equivalent atoms in NMR spectrometry? I would rather avoid rules like the one that says "if you can substitute the hydrogen with another atom and it gives the same compound, the hydrogens are equivalent". I would rather like an intuitive way to think about it, if it's possible!


texts:
In our office, we discussed today what the exact definition of a salt is and whether an acid itself can be classified as a salt.

Our first problem was that we couldn't get a definitive definition for what exactly a salt is. Wikipedia states:

  In chemistry, a salt is an ionic compound that can be formed by the neutralization reaction of an acid and a base.

Let's take, for example, carbonic acid: it is a molecule comprised of the ions $\ce{H+}$ and $\ce{HCO3-}$. We could say that this molecule forms due to the reaction of a base ($\ce{HCO3-}$) and an acid ($\ce{H_3O+}$):

$$\ce{H3O+} + \ce{HCO3-} \rightarrow \ce{H2CO3} + \ce{H2O}$$

Thus, it seems that the acid fulfills the definition above. We are pretty sure that acids are not considered salts. So where is the error in our reasoning?


texts:
The formerly degenerate $d$ orbitals of the tungsten atoms in the $\ce{WS2}$ monolayer are split into three groups: (1) $\mathrm{d}_{z^2}$, (2) $\mathrm{d}_{x^2-y^2}, \mathrm{d}_{xy}$ and (3) $\mathrm{d}_{xz}, \mathrm{d}_{yz}$ in the order of increasing energy with the large band gap between the first and the second groups.

Now the valence band maximum consists dominantly of $\mathrm{d}_{x^2-y^2}, \mathrm{d}_{xy}$ orbitals, whereas the conduction band minimum is composed mainly of $\mathrm{d}_{z^2}$ metal orbital.

So, the order of $\mathrm{d}$ orbitals in the first two splitting groups now is reversed, since the valence band is lower in energy than the conduction band. Where is the correspondence between these two facts?


texts: Why is it so difficult to create mock NMR spectra of macromolecules?

texts: From what I understand, if you have a NMR spectra, you can determine the structure of a macromolecule but it is very difficult to determine what the NMR spectra of an expected structure would look like? Why is this the case?


texts: Can the direction of electron flow in a voltaic cell be reversed?

texts: I am wondering if the direction of electron flow in a voltaic cell be reversed such that the cathode becomes the anode and vice versa. I understand this is not possible for two standard half-cells, but what about non-standard half-cells at STP ?


texts: What are the plastic connectors called (for glassware)?

texts: I can't remember for the life of me, and google isn't making it easy. e.g. the things labeled 24/40 etc., as in this picture:


texts: Where does the label ‘Dq’ to denote the field split in coordination compounds come from?

texts:
As established in a previous question, coordination compounds typically have a field split between the $\mathrm{t_{2g}}$ and the $\mathrm{e_g}$ d-orbitals.[1] This energy difference can be explained by the crystal field theory which assumes negative point-charges approaching a complex and destabilising orbitals pointing towards said point charges.

Commonly, the energy difference between the lower and higher orbitals is referred to by the relative value of $\Delta$ or the equally relative value of $10~\mathrm{Dq}$.

The latter is of interest to me. It is clearly used as a (relative) unit, because ligand field stabilisation enthalpies (LFSE’s) are typically given in values of $\mathrm{Dq}$ — e.g. $\ce{[Cr(H2O)6]^3+}$ (hexaaquachromium(III)) has an LFSE of $-12~\mathrm{Dq}$. But what does $\mathrm{Dq}$ mean and what does it derive from?

Note:

[1]: This is explicitly considering the octahedral case. Tetrahedral compounds split the d-orbitals into $\mathrm{t_2}$ and $\mathrm{e}$. This distinction is, however, not relevant to the question.


texts: What's the simplest way to etch Nickel and Chromium sputtered layers?

texts:
I have to etch a very thin film (50 nm) of Nickel ($\ce{Ni}$) on a 100 nm $\ce{SiO2}$/$\ce{Si}$ substrate. Additionally, there is a ~5 nm adhesion layer of $\ce{Cr}$ under the $\ce{Ni}$ that I'd also like to etch.

So I found this page which has a fairly long list of etches for $\ce{Ni}$ and $\ce{Cr}$.

Ni:

1 : 1 : 1 - HNO3 : HAc : Acetone
1 : 1 - HF : HNO3
30% FeCl3
3 : 1 : 5 : 1 - HNO3 : H2SO4 : HAc : H2O 85 C 10 microns/min
3 : 7 - HNO3 : H2O
1 : 1 - HNO3 : HAc
10% g/ml Ce(NH4)2(NO3)6 : H2O
HF, concentrated – slow etchant
H3PO4 – slow etchants
HNO3 – rapid etchant
HF : HNO3 – etch rate determined by ratio, the greater the amount of HF the slower the reaction
4 : 1 - HCl : HNO3 – increase HNO3 concentration increases etch rate
30% FeCl3
5g : 1ml : 150ml - 2NH4NO3.Ce(NO3)3.4(H2O) : HNO3 : H2O – decreasing HNO3 amount increases the etch rate
3 : 3 : 1 : 1 - H3PO4 : HNO3 : CH3COOH : H2O ~15min/micron @ RT with air exposure every 15 seconds

Cr:

  2 : 3 : 12  KMnO4 : NaOH : H2O
  3 : 1   H2O : H2O2
  concentrated and dilute     HCl
  3 : 1   HCl : H2O2
  2 : 1   FeCl : HCl
      Cyantek CR-7s (Perchloric based)    7 min/micron (24A/s new)
  1 : 1   HCl : glycerine     12min/micron after depassivation
  1 : 3   [50gNaOH+100mlH2O] : [30g K3Fe(CN)6+100mlH2O]   1hr/micron

I'd really like to avoid HF if I can (it terrifies me!), but I have pretty much everything else at my disposal.

So far, everything I've done has been at room temperature.

First I tried concentrated $\ce{FeCl3}$. No bubbling or signs of anything after ~20min.

Then I tried weak $\ce{H3PO4}$. Nothing.

Today I tried strong (98%) $\ce{H3PO4}$, nothing.

Then I tried concentrated fuming $\ce{HNO3}$. Nothing after ~1hr.

Then I tried about 1:1 $\ce{HNO3}$:$\ce{HCl}$, nothing.

Am I missing something here? Do the solutions need to be heated up or something?


texts: The Nomenclature Of Poly substituted benzenes?

texts:
I am confused as to the nomenclature of poly substituted benzenes. Would more preference be give to to priority order or the alphabetical order? In this pdf, 4-aminophenol has been cited as more correct rather than 4- hydroxyaniline. However, there are some websites which site the other one as more correct. What would be the correct nomenclature. A reference from one of IUPAc's books itself would be great.

Thanks a lot!!


texts:
Why do we call a solution that has been centrifuged a supernatant? It seems to me that a "natant" should be something that floats (from Latin "natare" meaning "to swim"), and a "supernatant" should be something which lies above the natant, not below it. Shouldn't the liquid be called a subnatant? Or maybe a superprecipitate?

Edit: fixed Latin (see below)


texts: How can I determine if a chemical will dissolve aluminum oxide, on paper?

texts:
I am trying to clean some corroded aluminum. In my quest to find out how, I've stumbled across a lot of bewilderment and misinformation, and a lot of different feasible techniques as well.

My question is: How can I determine, on my own, whether something will dissolve aluminum oxide (room temperature) or not? Like, just by looking at chemical formulas.

I'd also need to be able to check to make sure a chemical that dissolves aluminum oxide doesn't also dissolve the good aluminum.

My goal is to be able to figure out not only if a given chemical will dissolve it, but also to come up with an idea of which chemicals that I don't know about may also dissolve it.

As a bonus it'd be nice to determine the temperature at which a reaction would occur if it's a bit higher than room temperature so I can determine on my own if I can apply a reasonable amount of heat to make something work.

I know very little about chemistry except a basic understanding that things react and can be described by equations, and that reactions absorb or release some amount of quantifiable energy.

Aluminum oxide is Al2O3.

Sorry I do not know how to tag this.

Also I'm not sure if "dissolve" is the right word. To be clear I use it in a way that means if I apply the chemical to corroded aluminum, it'll make the corrosion go away into the air, or turn back into aluminum, or at least make it easy to scrub or wipe off.


texts:
What is the structure of the molecule $\ce{N5P3}$? $\ce{N5P3}$ is not documented online, so could anyone please comment on the structure of the molecule:

How many ligands does each phosphorous atom have?
How many ligands does each nitrogen atom have?


texts: Is there a relationship between bond strength and polarity?

texts:
I believe that a more polar bond would be stronger, since it would be similar to an ionic bond.

However, this seems to be wrong when applied to the study of acidity of some compounds.


texts: My textbook says that $\ce{SO2}$ dissolving in water produces sulfurous acid, but that seems to be a chemical change. But $\ce{NaCl}$ dissolving in water is not a chemical change. Please explain.


texts: Comparing the bond strength between a polar bond and non-polar bond

texts: According to NCERT class 12 part 2, $\ce{ICl}$ has lesser bond enthalpy than $\ce{I2}$. I have read that non polar covalent bonds are weaker than polar covalent bonds as in polar covalent bonds partial opposite charges develop on the bonding elements which leads to extra electrostatic interaction between them which is absent in non polar bonds. So according to what I read the answer should have been opposite. Please let me know where this logic is wrong. Also using this logic I understood that ionic bond is stronger than covalent bond.


texts: Why is WF6 stable whereas CrF6 is unknown?

texts:
$\ce{F-}$ is a hard base since it is small and relatively polarizable.

Both $\ce{Cr^6+}$ and $\ce{W^6+}$ are hard acids, but shouldn't $\ce{CrF6}$ be favored since it would be a smaller hard acid?


texts: Writing the net reaction for reaction of sodium hypochlorite with hydrochloric acid and potassium bromide

texts:
I am currently taking a general chemistry course and during a lab they had us do the following procedure:

Place $\pu{2 mL}$ of $5\%$ $ \ce{NaClO} $ solution in a test tube.
Add $10$ drops of cyclohexane.
Add ~$10$ drops $\pu{6 M}\,\ce{HCl}$
In another test tube, add a pinch of solid $\ce{KBr}$
Use a dropping pipette to withdraw the chlorine/cyclohexane layer from above and add it to the test tube containing $\ce{KBr}$

When I did this, the mixture turned dark red and bubbled with a hint of purple to it. In my lab report, my teacher wants me to write the net ionic equation(s) of this reaction, but I have no idea how to do that.
How would you proceed?


texts: What is the difference between hexanes and petroleum ether

texts: I'm trying to use hexanes as the nonsolubilizing recrystallization solvent in a multisolvent recrystallization (benzene is the solubilizing solvent) that requires an oxygen free atmosphere and hexanes is present in the glovebox. I am using it in place of light petroleum ether (not in glovebox) and was wondering what the differences between hexanes and light petroleum ether were to determine if I can adequately substitute the two.


texts: Does the reaction of 1-bromobutane with cyanide ion follow an SN1 or SN2 mechanism?

texts: In my textbook it's mentioned that the reaction undergoes $\mathrm{S_N2}$ mechanism. I understand that the carbon attached to the bromine is primary, but both solvents here are polar protic solvents, which favour the $\mathrm{S_N1}$ mechanism. Can anybody explain how to reconcile these?


texts: Determination of percentage of Methanol in an Alcohol based hand sanitiser

texts:
Note: I am looking for advice on a chemical test - not a sermon.
I expect that this is entirely on topic in this forum, downvotes and sermon comment notwithstanding.
More than about 5% of Methanol in alcohol based hand sanitisers indicates that corners have been cut during manufacture and that the product should be avoided.
I'm looking for an easy test to determine the approximate percentage of Methanol in an Ethanol / Methanol hand sanitiser mix. Many hand sanitisers may contain small percentages of Methanol (typically in the 1% - 5% range) and this is acceptable. Anything over 5% I'd like to avoid. Much over 5% (say 10% +) I'd like to be very clearly distinguished. If actual approximate percentage can be indicated, so much the better.
Ideally I'd like a test with either low cost, simple to use, readily available non-hazardous reagents (one can hope) or failing that, something that can be prepackaged for easy use by the unskilled.
In web searches I found a range of tests for Methanol but most were not very quantitative and most were not intended to work in an ethanol-methanol mixture.

Background: Added:
Some guy y'know said:

Using disinfectants outside of a heathcare environment is still nonsense in the year 2020. Using disinfectants of questionable provenience is simply hazardous. Don´t do it.

The use of hand sanitisers is well covered in recommendation documents from regulatory authorities in many administrations and by internationally relevant bodies. Sanitisers are sold under regulatory guidelines which if followed would guarantee their safety when used appropriately. In the US many out of specification brands are being sold which are indistinguishable from those which comply. Several of the largest US sellers have been selling out of spec product. There is no way to determine provenance based on labelling.
While the use of soap and water is often a good or even superior solution it is incorrect to suggest that the use of sanitisers in general applications is nonsense.
In this instance I am interested NOT in their efficacy or application but re their specific bonafides with respect to a crucial component which is known to be used in excessive and illegal amounts in some cases.
I'm an engineer. Sanitisers are sold by a wide range of manufacturers and repackagers. I read labels, note sources, note claimed contents and viscosities and residence times and more.


texts: Is it possible to oxidize ether to ester?

texts: Is it possible to synthesize an ester from an ether in a single step? For example if I had an ether $\ce{(R-CH2-OR')}$, can I oxidize it so it will be an ester $\ce{(R-CO-OR')}$.


texts:
I'm doing a research project where we analyzing the structure of sand after a certain process. To get a better idea of the internal structure of the sand, we use different colors to visualize the movement of the particles. However we can't actually observe that structure since sand is not a solid substance. Therefore we need a way to solidify the sand without changing the structure.

We figured we would need some sort of liquid which we can pour into the sand container (the container is 2x1x0.2 meters) so that it will solidify. In other words, how can we solidify sand?

Using a transparent container is not really an option since we are curious about the structure in the center which we cannot see... unless we use transparent sand ;)

Note: we are using 'regular' beach sand.

EDIT:
I have read through all the answers and they are great! I can't accept any answers just yet since we need to figure out which method we will use, but it looks promising! We started with 0 and now we have some great ideas going with your help!


texts: Why does covalent bonding satisfy atoms?

texts:
Having to retake an introductory chemistry course has gotten me thinking. Covalent bonding is where electrons are shared between two atoms that both want more electrons.

Let us take $\ce{O2}$ as an example.

The red and purple oxygen atoms share 2 electrons. This means that they now both have 8. Fantastic!

However, electrons do not sit around statically but rather buzz around randomly. If the electron moves around, then on average having 4 electrons between 2 atoms means 2 electrons each. This means no one is any better off than from when we started.

My question is, seeing as the electron sharing would actually mean that on average each atom still only has 6 electrons, how can they become stable in this covalent bond?


texts: Which salts precipitate from a potassium/sodium chloride/sulfate solution?

texts:
This is not a homework question. I am not in any course of study. The following question arises from my personal curiosity. If 1 mole of sodium sulfate and 2 moles of potassium chloride are dissolved in water, and the solution is gradually evaporated, which salts precipitate, and in which order?

There are four possible single salts that could be precipitated, namely $\ce {Na2SO4, K2SO4, NaCl, KCl}$, as well as mixed salts with the general formula $\ce{((Na,K)Cl)_x.((Na,K)2SO4)_{1-x}}$, but I don't know how to work out which ones, or what the sequence would be, since I am a complete ignoramus regarding the chemical thermodynamics of these salts, their solutions, and their precipitation from solution. I do understand the basic concept of Gibbs free energy, which I guess would be involved here.


texts: Finding the valency of transition metals in coordination complexes

texts:
I understand how to find the valency of atoms in small organic compounds. For instance, for CH4, the valency of carbon is 4, while the valency of each hydrogen is 1. But for a coordination complex, for instance:

How do I find the valency of the center metal?
And if the center metal was bound to another metal:

How would the valency calculation change, if at all?
I need the valency of these transition metals because I wish to ultimately find the d^n configuration of the transition metal in the complex via the formula:
n = group number - valency
EDIT: If you have a different approach (apart from using valency) for finding the d^n configuration of the transition metal, feel free to suggest that instead.


texts: We're learning about emission and absorbtion spectroscopy, and how an emission spectrum is produced by passing a high voltage through a gas, and an absorbtion spectrum is produced by shining white light on a gas. Since both techniques seem to be inputting energy into the sample, why don't both produce an emission spectrum (as the electrons fall back down to their 'natural' energy state)? Also, why do the electrons even fall back to their original energy state - since a constant stream of energy is being delivered, why don't they stay at an elevated state until that stream of energy stops?


texts:
I want to know what is the way to determine a compound's composition by just seeing the name. For example, if I see the name

"copper (II) sulfate"

How would I go about deducing that its formula is CuSO4? I know that copper(II) refers to the copper cation with a +2 charge. I know sulfur can have either a -2, +4, or +6 charge. And I know that oxygen has a -2 charge. I also know that an ending of "-ate" means a high amount of oxygen. But it doesn't specify exactly how many oxygen atoms I'll need. I'm new to studying chemistry so excuse me if this seems like a bad question.


texts: Resemblance of molecular orbital formed by mixing of s and p orbitals to hybridised sp orbital

texts:
See the following two images.

I think that the two orbitals should not resemble each other because s and p orbitals overlap in different fashions in the two cases.

In the case of sp hybrid orbital, both s and p orbitals are centred at the same point. As a result, s orbital does constructive interference with one lobe and destructive interference with another lobe of p orbital.

But in the case of molecular orbital, s and p orbitals are centred at different nuclei (and those nuclei can't be at the same point). Then how come the resultant molecular orbital resembles the sp hybrid orbital?

The right lobe of the molecular orbital should get enlarged due to constructive interference of s and p orbitals, but why does the left lobe get diminished? Shouldn't it remain as it is in the p-orbital?


texts: Electrolysis in aqueous solution – which equations to use to predict product at each electrode?

texts:
When trying to work out what will be produced at each electrode during electrolysis, I'm confused as to which equations to use for hydrogen and oxygen.

For instance, an electrolytic cell containing aqueous nickel(II) bromide, with a nickel cathode and a platinum anode.

At the cathode:

$$\ce{Ni^2+ + 2e- -> Ni}$$

I have read that this does not occur because $\ce{Ni^2+}$ is a worse oxidising agent than $\ce{H+}$, which makes sense because $\ce{H+}$ is lower down on the left side of the electrochemical series meaning its reduction is more feasible.

Water is therefore reduced at the cathode:

$$\ce{2H+ + 2e- -> H2}\quad E^\circ=0.0\ \mathrm V$$

or:

$$\ce{2H2O + 2e- -> H2 + 2OH-}\quad E^\circ=-0.83\ \mathrm V$$

The second equation, however, has water higher up in the electrochemical series. This would suggest nickel should actually  be reduced in preference to water.

How do I know which of the two "water-reduction" equations to use?

This is even less transparent for the anode, where bromide should be oxidised to bromine, but there are also two equations showing production of oxygen: one below and one above bromide in the series:

$$\begin{alignat}{2}
\ce{O2 + 4H+ + 4e- &-> 2H2O}\quad &E^\circ&=+1.23\ \mathrm V\\[6pt]
\ce{O2 + 2H2O + 4e- &-> 4OH-}\quad &E^\circ&=+0.40\ \mathrm V
\end{alignat}$$

I don't understand which of these equations should be used and how you're supposed to know which to use.


texts: Non central chirality in cheminformatics?

texts: What are compact cheminformatics structural representations that allow to deal correctly with axial chirality, such as in binaphthyl compounds or metal complexes?


texts: Calculate the number of moles produced per hour per liter of air?

texts:
A reaction of importance in the formation of smog is that between ozone and nitrogen monoxide described by

$$
\ce{O3(g) + NO(g)->O2(g) + NO2(g)}
$$

the rate law for this reaction is:

$$
\text{rate of reaction} = k\left[\ce{O3}\right]\left[\ce{NO}\right]
$$

Given that $k = 2.98 \times 10^6\ \mathrm{M^{–1}\cdot s^{–1}}$ at a certain temperature, calculate the initial reaction rate when $\left[\ce{O3}\right]$ and $\left[\ce{NO}\right]$ remain essentially constant at the values $\left[\ce{O3}\right]_0 = 5.34 \times 10^{–6}\ \mathrm{M}$ and $\left[\ce{NO}\right]_0 = 7.99 \times 10^{–5}\ \mathrm{M}$, owing to continuous production from separate sources.

So, I have found that by using the rate of reaction equation

$$
\text{the rate of reaction} = $0.00127\ \mathrm{M/s}
$$

Now I’m wondering how to calculate the amount of substance of $\ce{NO2(g)}$ produced per hour per liter of air.

Right now, my idea is that you can take

$$
\left(1.27\times 10^{-3}\ \mathrm{M}\over\mathrm{s}\right)\left(60\ \mathrm{s}\over{1\ \mathrm{min}}\right)\left(60\ \mathrm{min}\over{1\ \mathrm{h}}\right) = \ce{NO2} \,\text{per hour per liter of air}
$$

Is this the correct way to go about it? I was thinking that the seconds and minutes would cancel leaving just $\mathrm{M/h}$ and then if you multiply by 1 liter it would be $\mathrm{M/(h\times L)}$.


texts:
My book says

  To compare the acidities of two compounds, compare the stability of the anions formed by loss of a proton with respect to the original compound.

Suppose we have acetic acid and ethyl alcohol. Now on losing a proton, they form the respective anions:

My book again says

  The acetate anion is resonance stabilized whereas in the ethoxide ion the charge is localized on the oxygen atom. Hence, acetate ion is more stable as compared to the ethoxide ion and hence, acetic acid is the stronger acid.

The problem is we have only compared the stabilities of the anions with respect to each other and not with respect to the original compounds. So how do we know that it is correct?


texts: Why are certain substances clear/invisible? Can we create invisible objects?

texts:
This is more so a question of how light interacts with matter. For example, why are substances like oxygen generally invisible? If the light hitting the molecules were absorbed, it would appear black, right?

Also, could we create invisible materials?


texts: Why do we use external pressure to find force exerted by gas on a piston in a closed vessel during its expansion?

texts:
I was reading a book in which i got confused due to this. A gas is in a vessel covered by a friction-less piston. Gas pressure is more than outer atmospheric pressure (which is constant) due to which it expands. Since it expands and move the piston outward, it does work on it which is calculated by force times displacement. In finding force we use Force = Pressure times Cross section area of piston. In finding this force to calculate work why are we using Pressure on piston by atmosphere and its weight and not pressure exerted by gas. Why? Can you also tell how the correct work done by gas can be calculated.
Thanks.


texts: Is it safe to drink and what else can it be used for?


texts: Why must polar molecules be asymetrical?

texts:
As I understand, polarity in molecules comes from the difference in electronegativity or the ability of the atoms to attract eletrons so the electrons spend more time or are more probable to gravitate more around the atom with stronger electronegativity right? So I wonder why polar molecules must necessarily have an asymetrical structure? (as I've read on multiple sites). Shouldn't a symetrical atom with strong electronegativity with 2 atoms bonded linearly 180° on both sides which are significantly less electronegative, be polar since the electrons would gravitate more towards the center and the sides would then be more positively charged? What am I missing here?

Why is the first molecule (1) not possible? Is it becuase of the less polar atom on the left side repells electrons just as much as the one on the right? But then the electrons would still orbit the middle atom more because its more elctronegative, right?


texts: Does clay absorb water because of polarity?

texts: From what I have recently learned about ceramics, clay is essentially sheets of silicon and oxygen, bonded by covalent bonds. Between them, water keeps clay from forming a full lattice of $\ce{SiO4^{2-}}$. What I am wondering is, does clay absorb the water because of the water's polarity, i.e. are water molecules bonding with hydrogen bonds to the negatively charged oxygen atoms of the ceramic sheets? Or is water there because pressure from the environment forces it in between the sheets (which I know would then be a physics question)?


texts: Methods of dissolving a gas into a liquid

texts:
I know that carbon dioxide is dissolved into water in a soda fountain using a sort of a tubular manifold that mixes the water with pressurized carbon dioxide as it goes through it.

Is that the best way to dissolve a gas like carbon dioxide into cold (refrigerated) water, or are there better methods? Is there an official name for this kind of device, "aspirator," maybe? How is this done in the lab?


texts: What can create black stains on metal after putting HCl on a tap full of limestale?

texts:
After putting HCl on a tap part that was really attacked by limescale, lots of gas began to form and limescale progressively disappeared, as expected.

However, the reaction left behind black soot-like deposits, on the cup holding the reaction but also on the sink (when washing away), that don't go away easily.

So, what could be this black deposit made of?

Also, the chromium-plated parts of tap began turning a bit red after exposure to HCl and the non chromium-plated parts turned black and slowly began to be covered with some kind of white powder (see the picture below).
What is the material of the tap that would explain this behavior?


texts: Is there a point where further dilution of ethanol is not exothermic?

texts:
Diluting concentrated ethanol with water is exothermic. Diluting 95% refined spirit into 40% vodka makes the resulting product definitely warm. Dilution of 60% absinthe with water that is cool, but warmer than "nearly freezing" results in a lukewarm, unappetizing drink. I haven't noticed the effect when diluting weaker alcohols though.

Is there a threshold of concentration where further dilution of water-ethanol mix doesn't produce heat? Or is it merely an asymptotic relation, where at lower concentrations the effect becomes hard to notice?


texts: What should be the mechanism for hydrolysis of benzalchloride to benzaldehyde?


texts: Why does lithium forms no ethynide on reacting with ethyne?

texts: Sodium Metal when treated with ethyne forms mono and di sodiumethynide why doesn't  lithium ?


texts: Can the energy used required to break a molecular bond of plastic (e.g. - PVC) be used to dissociate plastics into its constituent elements?

texts:
Dear Molecular Chemists and Physicists,
Pardon my ignorance, but why can not plastic polymers be broken down into their constituent elements?
Common bond energies are shown in these two separate sources:
Source 1: https://science.jrank.org/pages/984/Bond-Energy.html#:~:text=A%20higher%20bond%20energy%2C%20therefore,is%206.02%20%C3%97%2010%2023.
Source 2: https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Chemical_Bonding/Fundamentals_of_Chemical_Bonding/Bond_Energies
According to Wikipedia (https://en.wikipedia.org/wiki/Polyvinyl_chloride) PVC = (C2H3Cl)n.
According to source 2: The average bond energy (kJ/mol) of the following are:
C-C = 347 kJ/mol
C-H = 413 kJ/mol
C-Cl = 339 kJ/mol
This is an image of the molecular formula for PVC (source = Wikipedia "Polyvinyl Chloride"):

If I want to break down plastic (PVC) into its constituent elements, the amount of energy required to break each individual bond of one mol of PVC is likely something around (413kJ)x2 + 347kJ + 339 kJ = 1512 kJ. This means, 386,170,212,765.9574 kJ are needed to break apart all PVC made annually. It takes 3.1x10^7 kJ to move a 1000lb car at 55mph for 1 hour (https://www.physicsforums.com/threads/energy-to-move-a-car.246885/). Does this mean, the energy to break down a year's worth of PVC is the same as moving twelve-thousand-four-hundred-fifty-seven 1000lb cars at 55mph for 1 hour? (Some of the calculations are below)
According to this source, https://www.webqc.org/molecular-weight-of-PVC.html, the molar mass of PVC = approximately 94 grams/mol. I read about 40 million tons of PVC are produced a year from the same Wikipedia site referenced above. This = approximately 3.63 x 10^13 grams/year.
Why is this not a solution for managing the plastic humans produce? I understand that the individual elements may enter unstable states alone and naturally desire to recombine with the other individual elements to be in a more stable state, so possibly a cleverly designed system can be used to separate each element into different isolated locations (like how water is split into Hydrogen and Oxygen in two separate containers). This seems like a sensible strategy to me, so what am I getting wrong here? Why is this not done?
Thank you,
Robert


texts: I understand that the pH of solutions decreases as the temperature increases but is there a reason as to why some solution's pH decreases more than others even if the temperature change is the same?


texts: Confusion about the choice of axis for Molecular Orbital Theory

texts:
This video from MIT OpenCourseWare says that pi bonds and anti-bonds are for 2px and 2py, i.e., $\pi_{2px}$, $\pi_{2py}$ and $\pi_{2px}^*$, $\pi_{2py}^*$ and sigma bonds and anti-bonds are for 2pz i.e., $\sigma_{2pz}$ and $\sigma_{2pz}^*$.

But in my reference books it says pi bonds and anti-bonds are formed for 2py and 2pz i.e.,  $\pi_{2py}$, $\pi_{2pz}$ and $\pi_{2py}^*$, $\pi_{2pz}^*$ and sigma bonds and anti-bonds are for 2pz i.e., $\sigma_{2px}$ and $\sigma_{2px}^*$.

Which is actually the right one? Please explain.


texts: Is this the lowest chair conformer of Beta D-galactose

texts:
I drew the conformer (below) and I'm wondering if this is the most stable chair conformation.

Three of the bonds are equatorial so it looks like the most stable to me.


texts: Comparing C=O bond length in CO2 and CH2O

texts: Why is the C=O bond in $\ce{CO2}$ shorter than that in $\ce{CH2O}$? How can I use hybridisation theory to explain this?


texts:
I know that the best source of lye is hardwood. A brief search tells me that Bamboo is considered a hardwood of the monocotyledon variety. I've done a lot of searching to find this answer, but I can't seem to find if I can use the same process with bamboo ash as I would with, say, Apple ash, to extract lye.

My question is two-fold:

1) Is it possible to extract lye from bamboo ash?

and if so,

2) Would this lye be a quality lye, capable of being used to create bar soap?


texts: How is it possible to account for the fact that NH3 is a weak base in water but a strong base in HCl?

texts: I understand that the solvents differ in their acidity but why does this affect the basicity of the solute?


texts: Proton affinities in machine readable format?

texts:
Short: How to get proton affinities for a large list of chemicals? A database? A programming API?

Longer:

I have ca. 2000 chemicals (downloaded from MCM, mostly organics that occur in the atmosphere and their reaction products). I would like to try to get proton affinities for as many of the 2000 chemicals as possible.

I know how to look up the proton affinity for a chemical in the NIST Chemistry WebBook (for example isoprene). But I would prefer to get a machine readable database, or a Python API (or any programming language), to get these nicely in a program code.

What options do I have?

(I am not going to get 2000 values by hand, so my last option would be to write a small web scraper to make these 2000 web queries)


texts: Looking for linear non polar compound which is used heavily due to its boiling or melting temperature or its density

texts:
So my son was given an exercise to find some linear non polar compound that is used heavily due to convenient boiling or melting temperatures or its density.

Having no training in chemistry I have no idea how to help him. I tried to look for a kind of search engine for chemicals just to see what kinds of compounds fit the bill, but I cannot find anything.

Any help is appreciated.


texts: What is the mechanism of ring contraction of 6-bromo-7-methoxy-2,3,4,7-tetrahydrooxepine from seven to five?

texts:
I have recently come across a paper from here.I have tried to workout the mechanism for the following reaction presented in the paper.

I was able to workout mechanism till acetal formation.It is a ring expansion from six to seven. However,the next step is a ring reduction from seven to five upon heating.

Can someone please explain what is actually happening during ring reduction, and why it happens?


texts: The violation of a certain rule or principle in the following electronic configuration

texts:
I'm to find the violation of a certain rule or principle in the following electronic configuration:

$$\ce{1s^2 2s^2 2p^1_x 2p^0_y 2p^0_z}$$

$n+l$ rule is not violated because: for $\ce{1s^2}$, $n+l=1+0=1$ so it is filled first, for $\ce{2s^2}$, $n+l=2+0=2$ so it is filled second, and so on.
Aufbau Principle is not violated because: the orbitals with minimum energy are filled first with electrons and $\ce{1s < 2s < 2p}$ which is the sequence of increasing energy orbital judged by the $n+l$ rule.

I'm quoting here a paragraph from my chemistry textbook of the chapter Atomic Structure:

  The orbitals given by a particular value of $l$ if $n$ is same, have the same energy and such orbitals are called degenerate. Like $l=1$ gives three $p$ orbitals specified as $\ce{p_x, p_y, p_z}$ and the p orbitals are said to be three fold degenerate. These orbitals are filled according to Hund's Rule.

The numerical value of the principle quantum number $n$ for $\ce{2s}$ and $\ce{2p}$ is the same; however, they don't have a particular value of the azimuthal quantum number $l$. For $\ce{2s}$, $l=0$, and for $\ce{2p}$, $l=1$, so $\ce{2s}$ and $\ce{2p}$ are not degenerate. So none of the three principles or rules whether Aufbau's, $n+l$ or Hund's is violated in this electronic configuration.

However, my friend says that there is a violation of the Hund's Rule in this electronic configuration, and according to him the right configuration is: $\ce{1s^2 2s^1 2p^1_x 2p^1_y 2p^0_z}$, which in turn violates the Aufbau Principle, because the orbitals of lower energy level have to filled first completely and $\ce{2s < 2p}$.

  So, which one of the electronic configurations is right, $\ce{1s^2 2s^2 2p^1_x 2p^0_y 2p^0_z}$ or $\ce{1s^2 2s^1 2p^1_x 2p^1_y 2p^0_z}$?

Note: The required electronic configuration is for the electrons in their ground state.


texts:
I am simulating some atoms under the Lennard-Jones potential and I would like to implement a cut-off radius, say at $r_c=2.5\sigma$. It is easy to keep the potential continuous, we can simply shift the potential using:
$$V'(r) = V(r) - V(r_c)$$
Where $V'(r)$ is the new potential. However, this does not guarantee continuity for the force
$$F(r) = -\frac{\partial}{\partial r} V(r)$$
I understand that there is no "trick"  to also make the force continuous. However, is there any method that allows me to make it continuous? For example using some kind of approximation of the force near $r_c$?


texts: How can platinum function as an "inert electrode" while having a standard reduction potential of 1.2 from its 2+ oxidation state?

texts:
In lecture I was taught that, in a galvanic cell at standard conditions, platinum is often used as an inert electrode when the species being oxidized or reduced exists only in solution, because platinum is "inert," which means it is very stable at and resists reduction or oxidation. This concept confuses me for two reasons:

Reduction means to lose charge, a.k.a. gain an electron(s). When the electrode has an electron passing through it in order to be transferred to another material, isn't it being reduced, albeit for a very miniscule amount of time? So, if we were to pause the cell during electron transfer and examine the iron wire and platinum electrode, we'd see a charge of -1 on both of them, correct?

I Googled the SRP of platinum, and this link states that $\ce{Pt^2+ -> Pt}$ has an SRP of $\pu{1.2 V}$. This translates to an "oxidation" potential of $\pu{-1.2 V}$. This one confuses me because, if we were to use a platinum electrode during the oxidation of $\ce{Mn^3+  +e^--> Mn^2+}$, which has an SRP of $\pu{1.54 V}$ (An "oxidation" potential of $\pu{-1.54 V}$), wouldn't the platinum electrode be the one to oxidize, as it has the higher value?

One concept that I'd like to imagine is that inertness is more about a lack of change in properties of the element as it reduces or oxidizes rather than it is about the "inability" to oxidize or reduce. This still doesn't explain how platinum can function as an electrode for species with a lesser standard reduction potential, though.


texts: Why is the rate of nitration greater for thiophene than toluene?

texts:
Toluene has a $\ce{CH3}$ group attached to the benzene ring and as a result due to the +I effect of $\ce{CH3}$, the electron density in the ring increases and it undergoes nitration faster than a normal benzene ring.
But what causes thiophene to have an even greater rate of nitration ?


texts: Is perchloride the same as perchlorate ion?

texts: I read about perchloride in a talk and after trying to search for its chemical formula, the search results imply that perchloride is actually named perchlorate. Is this correct?


texts:
TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)oxyl, or (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl) has the following structure:

Given that it's a free radical, why doesn't it react with itself, despite being capable of reacting with other radicals in the system itself)?

In addition, according to Wikipedia, it's a red-orange, sublimable solid. How can it be a solid despite being a radical?


texts: Metal and reactions with different temperatures of water

texts:
I knew that in warm water magnesium forms $\ce{Mg(OH)2}$ and $\ce{H}$ gas, and in steam it forms $\ce{MgO}$ and $\ce{H}$ gas (this is also the case for metals lower down the electrochemical table). However I came to realize that for those higher than magnesium all form metal hydroxide when react with water.
What is the mechanism for such a reaction?


texts:
Is the pressure of a gas proportional with the concentration of a gas?

Because you can also use the pressure instead of the concentration in the  equilibrium condition.


texts: Is an antiaromatic compound more stable than a non-aromatic compound because of more conjugation?

texts:
(image from a LibreTexts page (archive link))

It is shown that the antiaromatic compound is more stable than the non aromatic compounds 2 and 3 because of a more conjugated system. Here's the exact statement:

  In the first structure, delocalization of the positive charge and the π bonds occurs over the entire ring. This becomes apparent when we look at all the possible resonance structures as shown below.

  In the second structure, delocalization is only possible over three carbon atoms. This is demonstrated by writing all the possible resonance forms below, which now number only two.

  Finally, the third structure has no delocalization of charge or electrons because no resonance forms are possible. Therefore, it is the least stable of the three.

Is this correct? I thought that the conjugation in an antiaromatic compound destabilized it more than a non aromatic compound.


texts: Ignoring the difference of concentrations of reactants. Equilibrium

texts:
Recently at school, while studying equilibrium we learned that in problems where the initial concentrations of reactants and the equilibrium constant are given, there is a special formula to determine wether the change in reactants can be ignored where C is the concentration of the reactant with the smallest concentration and K is the equilibrium constant: L=C/K. We learned that if L is bigger than 500, we can consider the change in the reactants negligible. However this is where my problem lies: i do not see why the C is included, doesn't the size of K by itself tell us wether a little or a lot of reactants is transformed? Not to mention, some cases turn out flat out wrong. For example:
A+B=(reversible) 2C.

Initial concentrations: A=10^-20M
B=10^-20M.  C=0 M

K=10^-8

By the equation we learned, L=10^-12 and thus the variation in the reactants should not be neglected.
However, after doing the math, x~10^-24 which is 4 orders of magnitude below the beginning concentration of the reactants and completely negligible, is something wrong with my logic? Or did i discover a flaw in my textbook :)

Thanks


texts: Why is solubility of AgCN is higher in acidic buffer?

texts:
Solubility of $\ce{AgCN}$ is maximum in
A) Acidic buffer solution
B) Basic buffer solution
C) Pure water

According to me, it should not matter in which solution we are putting the $\ce{AgCN}$, because ultimately there is no common ion effect acting on it which should prevent or any effect that I could think of that should increase the solubility. But the answer given is A. Please explain.


texts:
How would you go about synthesising amino sugars from sugars? e.g. How would you synthesise the compound below from D-glucose?

Would adding ammonia ($\ce{NH3}$) to it work?


texts: interconverting Van Der Waal's equation for real gases from number of molecules to density

texts:
I want to ask a question about Van Der Waal's equation for real gases.
I was shown the following formula for real gases (VDW) which accounts for the liquification of water vapour which is not possible with an ideal gas model.
$$P = \frac{NkT}{V-Nb} - \frac{aN^2}{V^2} = \frac{\rho RT}{1-\rho b} - a \rho^2$$
which can be expressed using densities by making the denominators equal first:
$$P = \frac{NkT}{V-Nb} - \frac{aN^2}{V^2} = \frac{NkT}{V-Nb}\left(\frac{V}{V}\right) - \frac{aN^2}{V^2} = \frac{\frac{NkT}{V}}{\frac{V-Nb}{V}} - \frac{aN^2}{V^2} $$
but I appear to yield the result
$$P = \frac{\rho kT}{1-\rho b} - a \rho^2$$
where Boltzmann's constant $k$ has been switched for the gas constant, $R$. I can't find any sources that explain this derivation apart from "Molecular Driving Forces" by Dill, and he doesn't do a thorough conversion either.
How do I convert the numerator with Boltzmann's constant $k$ to the gas constant, $\rho$ which expresses VDW's equation involving densities?


texts: Why does the distance between atoms in a hydrogen bond impact the strength of the bond?

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Wouldn't the distance be irrelevant as after they are attracted they will just close the gap? E.g. once 2 magnets are close enough to be attracted, isn't the distance irrelevant to the strength of the bond between the magnets as they will just become flush against each other, making the distance between any 2 magnets that are attracted to each other equal.

Or is it perhaps talking about the other groups stopping the hydrogen and other atom becoming close?

Context:

Of the following, the factor that has the least effect on the strenght of a hydrogen bond in a molecule is the

type of atom to which the hydrogen atom is covalently bonded.
distance that the hydrogen atom is from the atom on the other part of the molecule
number of other hydrogen atoms atttracted to the atom on the other part of the molecule
type of atom in the other part of the molecule to which the hydrogen atom is attracted

(answer is 3, hence 2 must have some effect).


texts: What is the heaviest possible water using oxygen and hydrogen isotopes, and what might it's physical properties be?

texts:
After a cursory internet search, it appears to me that Hydrogen-3 (a part of Tritiated Water) is the heaviest stable* hydrogen isotope. Oxygen-21 is the heaviest isotope of Oxygen with a half-life of seconds, and Oxygen-16, -17, and -18 are the heaviest stable isotopes (again, this is based on an internet search and may not be accurate).
So could (3H2)(21O) conceivably be a thing? If not, what is the heaviest water possible, and what would some of its theoretical physical properties be? Would the mass overcome surface tension? Would there be stronger or weaker hydrogen bonds? And so on.


texts:
I have been given task to write possible reaction equations, determine oxidizer, reducer, write corresponding electron-equations and calculate electromotive force (I do not know if that is what you call it in English) of reactions:

Iron reaction with diluted sulfuric acid
Aluminium reaction with solution of sodium hydroxide

Could you be so kind and help me with this task?


texts:
If I understand correctly, solubility of organic compounds depends mainly on the presence of polar groups plus putting in the factor of the number of carbon atoms in the molecule.

So putting that in mind I do not understand why Glycine, an amino acid with two polar groups, the amine and the carboxyl groups, is considered non-polar and insoluble in water .


texts: Perturbational Molecular Orbital Theory - How to derive the results?

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I am reading Albright's Orbital Interactions in chemistry. The qualitatively perturbational treatment of molecular orbitals seem to be a central tool used throughout the book. I've referred to the Appendix for a thorough derivation of the theory. However, I got stuck at equation 22(a). I don't understand how it follows from everything that is spelled out before it.

Hopefully, somebody who has read the same book or is knowledgeable about this topic can help me out. Thank you!

Remark: I know how to derive the nondegenerate perturbational theory in QM but it seems that with MO theory the derivation is more complex, since we are combining AOs to form MOs rather than working with totally independent, orthonormal eigenstates as in QM.


texts: what is the difference between how taste and smell are detected?

texts:
Taste and smell are both chemical processes

  ... parts of the food dissolved in saliva come into contact with the taste receptors.[1] These are located on top of the taste receptor cells that constitute the taste buds. The taste receptor cells send information detected by clusters of various receptors and ion channels to the gustatory areas of the brain via the seventh, ninth and tenth cranial nerves. (https://en.wikipedia.org/wiki/Taste_bud)

, is there any difference in the way taste and smell receptors work?