texts:
Hi Everyone new to chemistry and learning lots but I had a question that I am having trouble working out.
I work for a vegetable grower and we make our own fertilizer.
My question is around the fish fertilizer. The brief description of the process is we use fish meal and mix it with phosphoric acid and enough water to make a paste. Let it sit a week then add, depending on volume a good amount of KOH. We also add a some skim milk and a small amount of molasses. This process among other things converts the protein in the fish to plant available nitrogen and gives us phosphorus and potassium.
I would love to understand all the chemical processes that are happening here and would like to understand how we are converting the protein in the fish meal to nitrogen. Is it phosphoric acid or KOH that is doing the work and how does the amount of these acids effect the process? Why is such a small amount of acid but a large amount of base used?
I have done my own research but coming up short in understanding what is going on and what the acid and base are doing.


texts: Based on Molecular Orbital Theory , how is it decided that the double bond in O2 molecule has one sigma bond and one pi bond?

texts:
My Chemistry textbook says this in regard to a C2 molecule:

  It is important to note that double bond
  in C2 consists of both pi bonds because of the
  presence of four electrons in two pi molecular
  orbitals.

Is it possible to account for the double bond in an Oxygen atom consisting of a sigma bond and a pi bond in the same way, based on MOT?


texts: I am having difficulties with analysing steroids in GC/MS

texts:
Is there anyone here that has already analysed estrone and 17beta-estradiol on GC/MS (HP5-MS column and MSTFA as derivatizing agent)?
Is it necessary to make a mixture of other reagents with MSTFA or can I just use MSTFA in the process of derivatization? How long does that process take to happen?


texts: How many electrons are there in the pi-system of cyanogen?

texts: I know that there are 18 electrons available for bonding in the entire molecule, and that 6 of these are used for sigma bonds. That leaves 12 left over. Which molecular orbitals best describe the locations of these electrons?


texts: Why does the chlorination of indene occur with syn selectivity in heptane?

texts:
In the chlorination of indene to form 1,2-dichloro-2,3-dihydro-1H-indene in heptane as solvent, the syn dichloride is formed as the major product, as reported in J. Org. Chem. 1980, 45 (25), 5150–5155):

The explanation I was given for this was that "in a non-polar solvent, the ion pair collapses quickly". What does this mean, and why is the stereoselectivity reversed, as compared to typical halogenations which proceed via a halonium ion intermediate to give anti dihalides?


texts: How do I write a procedure for creating a buffer?

texts:
I need to write an original procedure with exact numbers for creating a buffer:

Create a buffer using $\ce{CH3COOH}$ and $\ce{CH3COONa}$ that has a $\pu{pH}$ of exactly $3.75$.
A $\pu{50 mL}$ sample of your buffered solution has to be able to withstand the addition of $\pu{25.00 mL}$ of $\pu{0.10 M}$ $\ce{NaOH}$ solution.
"Withstand" here is defined as less "than $0.5$ change in $\mathrm{pH}$."
The buffered solution will break after the addition of no more than $\pu{35.0 mL}$ of the $\pu{0.10 M}$ $\ce{NaOH}$.
We are given $\pu{0.10 M}$ $\ce{NaOH}$ and $\pu{6 M}$ acetic acid.

Where I've got so far:
I took the $\mathrm{p}K_\mathrm{a}$ of acetic acid $(4.75)$ and the desired $\mathrm{pH}$ $(3.75)$ and put it into the Henderson-Hasselbalch equation:
$$3.75 = 4.75 + \log\frac{[\text{salt}]}{[\text{acid}]}$$
$$\log\frac{[\text{salt}]}{[\text{acid}]} = -1$$
So
$$\frac{[\text{salt}]}{[\text{acid}]} = 0.10,$$
which means we want the ratio $[\ce{CH3COONa}]:[\ce{CH3COOH}]$ to be $0.10$.
I think we can prepare a solution containing $\pu{0.10 M}$ $\ce{CH3COONa}$ and $\pu{1.00 M}$ $\ce{CH3COOH}.$ But with what we're given $(\pu{0.10 M}$ $\ce{NaOH}$ and $\pu{6 M}$ acetic acid), I don't know how to proceed and find exact numbers for a procedure.


texts:
Consider Gibb's free energy of a reaction in a closed system $G = H - TS$. Can $G$ ever be negative? (note, I am not talking about $\Delta G$)

I would suspect no because there is always some energy on every system.

What about $H$ and $S$? Are they nonnegative?

I would suspect yes because if there are bonds then they have internal PE and KE. I wouldn't know how to interpret negative disorder.

Is $H \ge TS$ always?

Variation on 1)


texts:
I have some sets made by well-known Danish plastic toy manufacturer from my childhood which I've been reviewing recently. Most of the elements was in a condition I was expecting (some yellowing, a little bit damage), but not with the smaller tyres. Originally, I found them quite oily/greasy by touch with some even leaving a bit of, what seemed to look like, liquid residue when removed from plastic wheels. Oh, and they were also full of domestic dust.
Didn't pay too much attention as I was going to clean them with the rest of bricks in washing machine using mild detergent. Upon drying I've check affected elements again and found that plastic elements exposed to rubber tyres were clean. These small tyres however, while their conditions was much better, they still had a bit of oily feeling by touch.
Tyres having this issues are up to 30 years old and rather small. Bigger ones are from the same time period but seem to be made of different material and did not show any signs of being oily even prior cleaning.
Affected tyres look like that if it matters (pictures just show the form, not the condition):

So I'd like to know few this around this issue:

What is going on here?
Is it possible to clean rubber tyres of this residue and get them back to normal condition? How long would it last?
Is it safe for plastic elements made of ABS and poly-carbonate (two most common plastic types used by this manufacturer) to have contact with rubbery tyres exposing issue explained above? Any other possible hazards?
Is there anything I could do to prevent from such issue happening to similar tyres in the future?

Disclaimer. I have not included a brand name for couple of reasons. First, my interest is purely from science/practical point of view. Next, I am not looking to accuse any one of some issues in case there are any. And last reason - idea was to hint a company, as I thought some may have better knowledge of exact materials used in above elements.


texts: Typography of atomic orbital subscripts p_x

texts: It the notation $\mathrm{p_x}$, $\mathrm{p_y}$ and $\mathrm{d_{x^2{-}y^2}}$, are the subscripts variables (and therefore should be in italics) or are they labels (labels for directions, I suppose, and therefore should be upright)?


texts: I understand the Jablonski diagram in that it has intersystem crossing from the singlet state to the triplet state, but how many spin switches are necessary to complete to phosphores? When an electron is excited to a singlet state, must it flip its spin state to enter the triplet state and flip once more to the ground state?


texts: Clar's rule of polycyclic aromatic hydrocarbons

texts:
Clar's rule  states that the Kekulé resonance structure with the largest number of disjoint aromatic π-sextets, i.e., benzene-like moieties, is the most important for characterization of properties of polycyclic aromatic hydrocarbons (PAHs). What is the reason for the validity of Clar's rule?
I mean why does polybenzoid structures follow Clar's rule (what is the mechanism lying behind it) and what is the reason for the stability of these structures?


texts: Electrolysis of Baking Soda separated by semi permeable membrane

texts: I have dissolved baking soda in battery water (de-ionized), in a glass beaker and used a food handling glove (vinyl) as a semi-permeable membrane to separate a graphite electrode from a copper electrode. This is for an experiment that will use the copper electrode for the reaction and not the graphite electrode. When I apply a voltage $(\pu{12 V})$ and use a multimeter to measure the voltage, I get roughly $\pu{11 V}$ passing through the vinyl glove, however, no bubbles are produced, but if I remove the glove and have both electrodes in the beaker, then loads of bubbles are produced. So, will my experiment still work if the voltage is passing through the glove and there are no bubbles?


texts: How many times can we recycle one sheet of paper?

texts: Its really interesting to see the process of recycling of paper (as shown in picture below) but at the same time I was thinking like for how many times can one sheet of paper can be recycled ?


texts: Why is tert-butoxide often used in elimination reactions when it is not necessary?

texts: I understand that tert-butoxide is used to favor the Hofmann product in elimination reactions due to its steric bulk (and thus inability to abstract a proton in a more substituted position); however, I have often seen proposed organic synthesis involving the use of tert-butoxide when it is seemingly irrelevant. For example, 1-bromobutane will undergo an elimination reaction with or without a sterically hindered base (such as tert-butoxide); however, anytime I see reactions involving elimination reaction with primary substrates, such as the bromo group in 1-bromobutane, tert-butoxide is used rather than ethoxide. Is tert-butoxide simply used to disfavor the formation of substitution products. Is its steric bulk enough to not allow it to act as a good nucleophile in substitution reactions?


texts: Safe reaction to maintain 30psi (2 bar) of gas, while that gas is released at random?

texts:
I'm going to use it to power a Lego Pneumatic Engine (LPE) (random example, not mine), that will be self-contained, and start and stop a lot using a throttle valve.  So the requirements are:

Use common materials to run the reaction

Might not even need to be a reaction.  Vapor pressure would do just as well.  See #5.

Be completely safe, both for indoor use with no special collection, and for the materials involved:

ABS Plastic for valves, cylinder walls, and plumbing hard lines
Rubber seals and hoses
Steel piston shaft

Fit in a small (0.5L) plastic water bottle

There's another bottle available, about 1/2 that size, that can be air-displaced into the main one through the standard rubber hoses and ABS hard lines (perhaps to start the process without losing a lot of gas), but I'd rather not use it if I don't have to.  It is available though, if needed.

Produce a large volume of gas (long runtime of the LPE)
Self-regulate to around 30psi (2 bar), so no worries about over-pressure when the LPE is not running

(this might be the tough one)

Not need special cleaning afterwards

My first thought was Baking Soda and Vinegar to generate CO2, with a pressure-regulated air pump to displace the vinegar into the baking soda.  But there are two problems with it:

The original reactants can get into the LPE as contaminants, which then need to be cleaned out.  (the reason for #6 above)
It doesn't stop at Lego's maximum pressure of about 30-35psi.  (the friction-fit hoses pop off around 37psi, and the reason for #5 above)

I have a design for a "smart" pump controller that accounts for most of the pressure coming from a finite-rate reaction and not the pump itself, but it seems a bit rube-goldberg-y to me, and still can't account very well for the expected run/stop pattern of the engine that uses it.

So, is there a different reaction that I can use instead, that can satisfy the requirements up top?

Some pictures may help:

The water bottle sits horizontally, under the black "hold-down bridge", with the bottom against the programmable brick.  (big yellow tower on the back)

"Steam" locomotive with Walschaerts valve gear.  And yes, it runs.  :-)  Both directions.

There's also an optional tender car with the other, smaller water bottle and the motorized air pump to displace something out of it, which is also controlled by the programmable brick.


texts: What does a simple or a complex substituent mean?

texts:
I am reading rules for IUPAC Nomenclature. The following statement is from my book.

  Prefixes di, tri, tetra, etc., are not considered in deciding alphabetical order for simple substituents but considered for complex substituents.

With respect to the above statement, what does a simple or a complex substituent mean? Could you please give any examples of simple and complex substituents. How to decide whether a substituent is simple or complex? Is there any rule to decide that?


texts: Why is the deposition of silver more uniform from [Ag(Cl)₂]⁻ (aq) than from Ag⁺?

texts: What determines the uniformity? Just a fun fact I am wondering about, because I saw cyanide solutions used in electroplating.


texts:
I've been investigating chemical kinetics and stumbled across the CHEMKIN program manuals and the JANAF tables. In the original CHEMKIN database they list 'standard enthalpy'. I've checked and this is not in fact enthalpy of formation as this is a separately listed value. What I'm confused about is that I cannot find any reference to molar enthalpy any where else except in the the introduction to the JANAF tables and the CHEMKIN database. What's more it lists the enthalpy of $\ce{H2O}$ and $\ce{H2O2}$ as zero and other substances have negative enthalpy. Questions:

Is specific molar enthalpy in comparison to water or some other substance?

If it is still a relative measurement of enthalpy what advantage does it provide over heat of formation in practical use?

How can the two substances both have the same enthalpy even if it is relative if one has an extra atom and an extra bond?

Am I completely wrong and the whole thing is something else entirely?


texts: Acid catalysed dehydration of 5-methylidenecyclopent-2-en-1-ol

texts:
I think the following reaction is NOT possible.

I could not find a mechanism for ring expansion. Is ring expansion possible in any way?
Is the following mechanism correct?


texts: Shouldn't MSDS data on products be publicly disclosed?

texts: I am wondering whether companies are required to disclose MSDS data on their products: toxicity, $\mathrm{LD_{50}}$, etc. Not only that, but I am wondering whether they are required to disclose the methodology that they used. I know that this isn't a legal forum, but some companies that I asked are unwilling to give details on how the toxicity was tested. What are some laws that are in place (regardless of country)? I thought that all MSDS data should be public.


texts: Synthesis via Sn2/Sn1, E2, E1: Choice of solvent

texts:
I uploaded pictures on http://www.physicsforums.com/showthread.php?t=765106

I was looking at the answers in my textbook. They seem to make incongruent choices of solvents.

In e) and j), why choose EtOH and H2O/CH3OH? I would rather choose an aprotic solvent like DMF to better allow Sn2 to occur. Especially with j), there is a lot of competition with E2 because OH- is a strong base and because we are attacking a secondary carbon.

I see this again in k). Secondary carbon attacked: why not add DMF to prevent E2 and get best yield?


texts: Is an alcohol-based spray cleaner ok for cleaning an aluminum heat exchanger?

texts:
Simple alcohols such as ethanol can, apparently, corrode aluminum. However, this corrosion reaction seems to be very slow at room temperature and below. Is an ethanol based, non-foaming spray cleaner, propelled by LPG and with an ethanol concentration of, say, about 20%-30%, some (about 2%-3%) alcohol ethoxylate (this acts as a surfactant) and a slightly basic pH (between 7 and 8), really ok to spray on a cold parallel-flow type heat exchanger without fear of any damage? Or should an alcohol-free cleaner be preferred in any case for that job?

My belief is that the corrosion can only happen when the aluminum object is actually submerged in pure alcohol. That little alcohol conveyed by the spray probably evaporates before having the chance to do any damage, but i'd like to understand the surfactant role better, i.e. if any added surfactant agent can act as a corrosion inhibitor.


texts:
The Born–Oppenheimer aproximation is said to be adiabatic.

What does "adiabatic" mean?
What would be a non-adiabatic approximation to the Schrödinger equation?


texts: Does the ammonium ion hydrogen bond with water?

texts:
What about oxonium ions, such as hydronium ion? Do these hydrogen bond with water?

If we see hydrogen bonding as a purely electrostatic phenomenon, then why not? Ammonium ion still has nitrogen bearing a partial negative charge. Of course it can interact with positively polarized hydrogens in an electrostatic way.

However, we also know that hydrogen bonding is partially covalent. So, it seems unlikely that the ammonium ion would be able to form any additional covalent bonds.


texts: What determines whether an aldol reaction will occur again or eliminate?

texts:
The product of an aldol reaction is a $\beta$-hydroxy ketone. This can go on to eliminate to form an alkene thus:

However, the species on the far left of the above diagram (the $\beta$-hydroxy ketone product of the first aldol reaction) can react through an aldol reaction again given that it has two more available protons at the $\alpha$ position.

How is it possible to tell which reaction pathway will occur? Is this the issue that is referred to when the Aldol reaction is referred to as "hard to control"?


texts: How can I compute molar concentration if I am given parts per trillion?

texts:
A question in my book asks...

You have a gas X that is found in quantities of $261~\mathrm{PPTV}$ (parts per trillion by volume). Compute the molar concentration at $283.15~\mathrm{K}$ and $101325~\mathrm{Pa}$.

Would you just find the volume using $\frac{n\mathcal{R}T}{P}$ for $1~\mathrm{mol}$ of gas, then multiply this answer by $261/10^{12}$?


texts: How much salt (or any other substance one can find in a kitchen) do I need to add to make water boil at 104 °C?

texts: I've seen some formulas around in other questions and Google searches, but my chemistry is pretty much dead so I have no clue where to find the relevant values to calculate it myself. I just need to make an oil bath at 104 °C, but I would prefer to use a water solution instead since it is cheaper and easier to clean up. Doesn't need to be salt, can be anything commonly available at your average household.


texts: Can plastic be used as fuel for vehicles?

texts: I don't have much of a background in chemistry, but I know that plastics are largely made of carbon, as is oil. Is there any way to "covert", i.e. a plastic water bottle, into a substance that can be used as fuel for ? Thanks.


texts: Will the ions in salt bridge be used up?

texts:
Ions in salt bridge move to the electrolytes of two half cells to balance the charges.

But will the ions in salt bridge be used up?

If it will, is the electron flow then stop?


texts: Why exception is noted in the solubility of lead salts?

texts:
There are many exception in the solubility of lead salts like:

Lead sulfate is insoluble in cold water whereas most of the sulfates are soluble in cold water.
Lead chloride is also insoluble in cold water but is soluble in hot water. Why?
Carbonates are generally insoluble in water but they dissolve in dil. $\ce{HCl}$ except lead carbonate.

What property of lead causes such type of exceptions?


texts: Do hydrogen sulfide and oxygen produce pure sulfur or sulfur dioxide? If both, under which circumstances does each scenario occur?

texts:
If both of the following hydrogen sulfide and oxygen chemical equations can occur, under what circumstances is the harmless pure sulfur and the toxic sulfur dioxide produced?
$\ce{2H2S + O2 -> 2H2O + 2S}$
$\ce{2H2S + 3O2 -> 2H2O + 2SO2}$
Specifically I have a fresh water aquarium with sand, plants, and small creatures I collected from a creek. I want to prevent hydrogen sulfide building up by oxygenation with an air pump, but I want to make sure the environment does not result in the harmful sulfur dioxide in the tank.


texts: Is this heterocyclic boron molecule aromatic?

texts:
What kind of aromaticity does the following molecule have?

I read somewhere that this is  an aromatic compound, but I believe that in order to be aromatic, it should have continuous resonance. I also think that there should be a break at B that causes no $\pi$ electrons to be shared among the B—B atoms...so I think this is non-aromatic. Is that correct?


texts: how does mass of carbon 12 is like this?

texts:
1u is defined as per carbon 12
so 1 atom of c have 6 neutrons and 6 protons both having mass more than 1u (Google)so total mass of carbon 12 is more then 12u (also there would be some mass of electrons) but it should be exactly 12u as u is defined such.So what should i interpret.I am confused how this is possible

I am just a school student just entered chemistry


texts: What is an alternate way of preparing a sodium hydrogen phosphate/sodium dihydrogen phosphate buffer through titrating an acid with a strong base?

texts:
So my friend and I are stumped. This is in the context of achieving the sodium hydrogen phosphate/sodium
dihydrogen phosphate buffer by titrating the acid with a strong base.
My friend says the answer would be H3PO4 + Na3PO4. In my case, I'd think that sodium hydrogen phosphate would be the acid (but I genuinely am not sure) that we'd titrate in that scenario and all we'd need then is a strong base (although I honestly don't know how to figure out what strong base in particular you must use.)
What's correct? Or what would be the correct way?


texts: Is there any experimental evidence for OClF5?

texts:
On page 88 and 89 of this document, the author laments that $\ce{OClF5}$ has still not been discovered. He says it would be "just about the ultimate possible storable oxidizer" (for rockets).

(Note: it's pages 88 and 89 as labeled by the writing on the page, not the pdf metadata.)

The text seems a little dated. Has anyone ever found/produced any $\ce{OClF5}$? A related compound, $\ce{OClF3}$, was made in 1970 (footnote on page 89). So this seems to indicate that one of those weird loopy pairs of electrons can be jammed/bonded with an atom of oxygen.


texts: Cis, trans diene reacting with trans dienophile in D-A reaction

texts:
I wonder if I predicted the products correctly, because it seems to be messier than I thought - there's a pair of diastereomers... Also, I feel that the endo/exo rule does not apply here. Am I correct in my understanding? I have never seen a reaction like the one I drawn mentioned anywhere before. Hopefully someone can help me out.Thanks!

Note, there's an example in Clayden reacting cis, trans diene with DEAD, but since there's no stereocenter at nitrogen we end up just getting trans product.


texts: How is indigo carmine used in Lowenthal-Permanganate titration as a redox indicator?

texts:
In a Lowenthal-Permanganate titration, cider tannins are quantified by titrating the cider with indigo carmine indicator and sulfuric acid against potassium permanganate. Tannins are antioxidants, so that means they give up electrons to reduce the potassium permanganate. The endpoint of this titration is when the blue analyte turns a yellow colour. According to Wikipedia, indigo carmine turns yellow when reduced.
What I don't quite understand is why the indigo carmine didn't reduce when it was in the presence of the antioxidative tannins before the potassium permanganate was added and why it turned yellow only after potassium permanganate was added.


texts: Reading CGTF basis from Basis Set Exchange site

texts:
I'm making a simple electronic structure code as an exercise, and I want to confirm that my understanding about basis set data from BSE is correct.
The CGTF of H in aug-cc-pVTZ basis is given as:
H    S
 33.8700000              0.0060680
  5.0950000              0.0453080
  1.1590000              0.2028220

H    S
  0.3258000              1.0000000

H    S
  0.1027000              1.0000000

H    S
  0.0252600              1.0000000

H    P
  1.4070000              1.0000000

H    P
  0.3880000              1.0000000

H    P
  0.1020000              1.0000000

H    D
  1.0570000              1.0000000

H    D
  0.2470000              1.0000000

END
S-type GTF is simple, but I have questions about the number of other high-l GTFs.
P-type GTFs
I think the values
H    P
  1.4070000              1.0000000

mean that $\chi = (1.00000) g_{p}$. Then Does that means there are three p-type function ($x$, $y$, $z$)?
D, F-type GTFs
If that so, in the upper case. How D, and F-type GTFs? Specifically, if we consider D-type GTFs, are there six gaussians ($x^{2}$, $y^{2}$, $z^{2}$, $xy$, $yz$, $xz$) or five gaussians following the atomic convention ($xy$, $xz$, $yz$, $x^{2}-y^{2}$, $3z^{2}-r^{2}$)?


texts: Is there an abbreviation for "something bulky"?

texts:
I want to draw a scheme that indicates the difference between the products formed in a reaction with a molecule that will form one thing when it has methyl or hydrogen substitution, but another thing when it has any substituent more bulky than isopropyl.

Is there any abbreviation (like "R" or "X") for "bulky"?


texts:
Learning about biodegradable polymers and non-biodegradable polymers. What exactly sets them apart though? Here's the formula from wikipedia for the biodegradable PHB:

and here for polypropylene, it's non-biodegrable counterpart

As far as I understand, biodegradable just means that bacteria will degrade it into other constituent parts. Is it just that bacteria is a picky eater and won't eat certain polymers? But they seem to be made of similar elements, and the bonds between are generally similar. Any help is helpful.


texts: Why does the opening of an epoxide occur via an Sn2 like mechanism when using a methanoate ion as a nucleophile and methanol as a solvent?

texts:
Below is a picture of the mechanism:

I understand the mechanism but what I don't understand is why it's $\mathrm{S_N2}$. The solvent used is polar and protic, there is a tertiary carbon that would be suitable for $\mathrm{S_N1}$ as well. For what reason does this reaction occur exclusively via $\mathrm{S_N2}$?


texts: What factors promote honey's crystallisation?

texts:
Honey is a complex mixture containing, probably, more than hundred compounds.
I understand that the % of those components will affect the crystallisation.
However, I am wondering what factors may speed up the crystallisation, apart from heat?


texts:
I found as I was preparing to teach "Introduction to thermodynamics" that there are varying definitions or examples of pure substances. For instance the text book I have to use "Thermodynamics an engineering approach, Cengel and Boles" defines a pure substance as one that has the same chemical composition throughout. Air in the gaseous form is cited as an example. Air in its liquefied form is NOT since it seperates into it's various components.

The Dummies book on Chemistry suggests that sugar can be considered a pure substance as it has the same chemical composition throughout. And water can be considered a pure substance for the same reason.

So would a homogeneous mixture of sugar and water be considered a pure substance? After all, a homogeneous mixture has "identical properties" throughout it's phases.

Yet another definition of a pure substance suggests that any material made of the same kind of atoms is a pure substance. So individual elements in the periodic table and stuff made "purely" of them are pure substances. Other stuff is just homogeneous or heterogeneous mixtures.

So are pure substances (irrespective of whether we view them as elements, compounds or mixtures) just very difficult to break down into their individual components?

Or would the definition of a pure substance change depending on who you speak to (chemists, phycisists, thermodynamicists)?


texts: Obtaining potassium silicate from sodium silicate

texts:
Is it possible to obtain Potassium silicate ($\ce{K2SiO3}$) from Sodium silicate  ($\ce{Na2SiO3}$) without using expensive lab equipment such as furnaces etc.?
For example, Calcium silicate may be obtained using the following exchange reaction:
$$\ce{CaCl2 + Na2SiO3 ->  CaSiO3 v + 2NaCl}$$
Substituting calcium chloride with potassium chloride probably will not produce a similar result as potassium has different (less) electronegativity than sodium, though I am not sure if the exchange reaction takes place because of electronegativity (only).
(The aim is to be able to not only produce potassium silicate, but also separate it for example, as an aqueous solution without other solutes.)


texts: Strong activation of phenoxide ion compared to others

texts:
I was told that in phenoxide ion, benzene ring is very strongly activated. The order my teacher told me was phenol < amine < $2^\circ$-amine < $3^\circ$-amine < phenoxide (for activation of benzene).
Example: Reimer–Tiemann reaction happens only in sodium phenoxide
So, what is so special in phenoxide that makes it so much activating? Also, why does oxygen contribute more in resonance than nitrogen, when it is more electronegative than the latter?


texts:
I am reading "Effect of Freeze-Drying on Quality and Grinding
Process of Food Produce": A Review by Timilehin Martins Oyinloye and Won Byong Yoon.
The problem is they are referring to the words "sold matrix" several times. I searched the internet but could not understand what does that mean. Any comments please? Is this term used in some other area not in Chemistry?
Full Text


texts: Hybridization of sulfur in sulfur dioxide

texts:
One of the canonical structures for sulfur dioxide - $\ce{SO2}$ - has sulfur (with a lone electron pair) double bonded to each oxygen atom to form a total of 4 bonds for sulfur - which can be achieved via valence expansion into empty d-orbitals.

What then is the hybridization of the valence-expanded sulfur?
It is described as sp². But how can that be? This seems unlikely
because d-orbitals are involved since the sulfur underwent valence
expansion.

On might imagine a pair of electrons from the 3s/3p oribital(s) being promoted to an empty d-orbital and then having the 3s and 3p orbitals hybridize in to sp².
If this is true it would mean that the lone electron pair of the
valence-expanded sulfur consists of 2 electrons occupying
and unhybridized d-orbital. But is this correct?


texts: Aldehyde and ketone nomenclature when aldehyde/ketone group is bonded to an alkyl group

texts:
The longest alkane chain is decane and, attached to the fifth carbon, is an ethyl group the end of which is double bonded to an oxygen atom. My best guess at naming it would be:
5-(ethyl-2-al)decane.

Here, the longest chain is again decane, but there is a propyl group and an oxygen atom double bonded not to the ends of the alkyl, but to carbon #2, which leads me to:
5-(propyl-2-one)decane
Now I have no clue as to whether I am right or not because I have never come across such molecules and I have just done what I found to be logical. Have I come to the correct conclusions?


texts: What happens to the shielding of the proton when an alcohol is oxidized?

texts:
The full question:

  For H-NMR, the magnetic field experienced by a hydrogen atom can be
  externally applied or internally induced or some combination of the
  two. When the applied and induced fields act in concert, a proton in
  these fields is said to be deshielded. Which of the following
  processes will result in the greater deshielding of the proton? Please
  choose from one of the following options:

  Removing nearby carbonyl groups
  Adding electropositive atoms like silicon
  Oxidation of primary alcohols with $\ce{KMnO4}$
  Reducing terminal alkyne groups

This is what the question is asking me, but I'm confused because if you oxidize a primary alcohol, this gives an aldehyde or a carboxylic acid (depending on reaction conditions), and the proton in question goes into forming water. So if an H disassociates, does this equate to a total deshielding, or how is this explained with respect to proton NMR?
I realize that water does show up on NMR spectra, but I'm unclear what I am being asked. It also obviously depends if this is primary, secondary, or tertiary alcohol.

The answer given is (3) Oxidation of primary alcohols with $\ce{KMnO4}$. I don't understand why.


texts: We know that some compounds can donate $\ce{H-}$ anion to attain stability. What are the conditions under which it occurs and what should be the extent of stability of the product for this pathway to be viable?


texts: Is methylchloride reaction with water SN1 or SN2

texts:
I wanted to know if methylchloride reacting with $\ce{H2O}$ would be SN1 or SN2.
Methyl halide would not react using SN1 because methyl carbocation is very unstable but it would also not react using SN2 because $\ce{H2O}$ is polar protic.
Please correct me if I am wrong. I think in this problem there would be no reaction. What are your opinions?


texts:
Do beta hydroxy aldehydes respond to Fehling's test?

I was told that it readily loses a molecule of water forming alpha beta unsaturated compound. But it still has an alpha hydrogen and I presume that it meets all requirements for a compound to respond to Fehling's test.

Please correct me if I am wrong


texts: Reactivity of different alcohols with NaNH2 and CH3I

texts:
Identify the final product (B) in the following reaction:

I'm not sure how $\ce{NaNH2}$ and $\ce{CH3I}$ will react with the different types of alcohol present here. According to my solution,ether was formed in place of $\ce{CH2OH}$ in the end, whereas the answer says that $\ce{CH2OH}$ group will remain unaffected. What am I doing wrong? Can anyone explain to me the full mechanism?


texts: Combination of polydisperse polymer mixtures

texts:
Say I'm given a mixture of batches of polydisperse polymers. I know the weight $w$, the number average $ \bar M_n$, and the weight average $ \bar M_w$ of each batch that was added to the final mixture. How would I go about calculating the $\bar M_w, \bar M_n$ and PD of the final mixture?

I'm thinking that the $\bar M_w$ value would simply be a weighted average of each of the batches, but I'm not quite sure how to get the number average.

In math, I'm thinking that $\bar M_{w,final} = \frac{\Sigma_{i} w_i \bar M_{w,i}}{\Sigma_i w_i} $

I haven't been able to reason what I should do to account for the differing numbers of molecules/moles of each batch. I think it should also be a weighted average, but using the numbers of each batch for weighting instead of the weight, but how would I calculate that?

Thank you


texts: why the formula of coca cola can not be find using chemistry?

texts:
i mean we have SPECTROSCOPY to stablish what molecules make a compound

and also we have advanced chemistry

so why is SO HARD to find the formula of coca cola ? simply buy a bottle examine it to check what molecules or ingredients have and copy it :D

but why is so hard ?


texts: Confusion regarding Finkelstein Reaction

texts:
In Finkelstein reaction we know when a primary alkyl chloride or bromide is treated with NaI in acetone, we get the corresponding alkyl iodide
Now acetone is a polar aprotic solvent and order of nucleophilicity in acetone is F->Cl->Br->I-. I have read some articles on chemistry.stackexchange which explain why the driving force behind Finkelstein reaction is the precipitation of NaCl or NaBr. But one thing I am still not able to get why the Carbon chlorine or Carbon Bromine bond breaks in the first place by a relatively weaker nucleophile ie I-.


texts: Why is the halogenation of an alcohol a multistep process?

texts:
Refer to the mechanism posted on this site, if you will: http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch08/ch8-10-3.html

When the alcohol attacks the sulfur center, the pi electrons in the oxygen sulfur bond are taken by the oxygen. Then pyridine sucks up the proton. Afterwards the oxygen donates those pi electrons back and the chlorine anion leaves.

Why doesn't the chlorine anion just leave? What's up with the oxygen shuffling electrons around?


texts:
Which of $\ce{S^2-}$ and $\ce{S}$ has smaller ionization energy?

On one hand, ionization energy of $\ce{S^2-}$ can be predicted to be smaller than that of $\ce{S}$ because it is "easier" to remove and electron from an electron-rich ion, which already experiences a lot of electron-electron repulsion and reduced $Z_\mathrm{eff}$.

On the other hand, $\ce{S^2-}$ has a stable noble gas electron configuration, and removing an electron would get rid of the noble gas configuration.

I could not find relevant data for the second electron affinity of sulfur, so I am unable to check the reasoning.


texts:
Typical filter paper used in chemistry lab (e.g. Whatman #1) exhibits autofluorescence in near UV with excitation maximum at 365 nm and emission maximum at 440 nm. It was reported in literature1 that fluorophores from filter paper can be extracted by PBS buffer in wide range of pH, and thus they are at least partially soluble in water. However, cellulose, the major component of filter paper, is not fluorescent in this wavelengths range and is insoluble.

What is the source of filter paper fluorescence? I assume it comes from paper pretreatment and bleaching, but what is chemical identity of fluorescent compounds in it?

Danielson, T. L. et al.; Impact of filter paper on fluorescence measurements of buffered saline filtrates. Talanta 2003, 59, 601–604.


texts: How does conductivity work for non-redoxed ions?

texts:
Related (very similar, but here I want a mechanism) https://physics.stackexchange.com/q/21827/7433

By the Kohlrausch law, all ions contribute to the conductivity of an electrolyte.

Now, as I understand it, the mechanism of conduction in an electrolyte is thus:

Ions migrate in solution
These ions get reduced or oxidized at the electrodes and converted to electrons
These electrons continue down the wire, leading to an increased/maintained conductivity/current

But, this mechanism doesn't work for ions which do not get redoxed--movement of ions in the solution cannot be translated to movement of electrons in the wire and thus it seems (to me) that conductivity should not increase.

But ions like $\ce{NO3-}$ have a comparable $\lambda$ (ionic molar conductivity)--so they experimentally do increase conductivity.

What is the mechanism for conduction via these ions?


texts:
Why is pyridine so much more acidic than other similar imines (5.5 versus ~9, see picture)? Wouldn't delocalization of the positive charge into the aromatic system stabilize it and hence decrease acidity? Also the lone pair of pyridine is not delocalized into the perpendicular $\pi$-system and hence not any less available than the one of the projected imine.

(Source: Organic Chemistry by Clayden et al. p. 1149. )


texts: How to calculate steric number of methyl free radical?

texts:
According to the definition, steric number  = number of atoms it is attached + lone pair.

In that way, I get 4 for methyl free radical which means sp3 hybridization . But that's wrong !
Why is this happening ?


texts:
Which one of the following is NOT a haloalkane?
A) Freon
B) Teflon
C) Iodoform
D) Vinyl chloride

Every compound here seems to me as a haloalkane: Freon, Teflon, iodoform, and vinyl chloride.
My text says the answer is vinyl chloride, but how?


texts:
In chemistry lab we perform experiments to find the unknown solution. I just want to produce some fumes in lab. We are only allowed to use few common dilute solution like $\ce{NH_4Cl}$, $\ce{NH_4OH},$ $\ce{HCl}$, and few more which are generally allowed to students.

Is it possible to form fumes in lab?


texts: Determining where a group will direct an addition

texts:
I'm looking at a phenol with a ketone in one of the meta positions being treated with $$ \frac{Cl_2}{AlCl_3} $$

I know the Alcohol is the stronger activator because ketone is a deactivator. I'm wondering how determine the major product of the addition.

I'm thinking the Cl will add to the other meta location of the Alcohol group due to it wanting more space around the ring, but I'm not sure if that's correct, due to not being sure how to determine where something will direct and addition.


texts: A Question on the Role of Triplet Oxygen in the Formation of Artemisinin

texts:
It is observed that whereas singlet oxygen is required for an ene reaction with an alkene to give an allyic hydroperoxide, triplet oxygen will react similarly with an enol to give an alpha-hydroperoxy aldehyde. (Example: see Chen HJ et al., Tetrahedron 69 (2013), 1112-1114.)

The drawing below shows two steps in the final sequence of reactions leading to the antimalaria drug artemisinin, as described in the cited article. The enol is formed by opening of the hemiacetal, and before it can tautomerize to the aldehyde, it reacts with atmospheric oxygen (in the dark, so presumably triplet oxygen) to give the alpha-hydroperoxy aldehyde shown. That in turn spontaneously folds up to give artemisinin (not shown). A concerted reaction of the enol with triplet oxygen, if it is a variant of the ene reaction, would be spin-forbidden.

Can anyone explain why this otherwise "forbidden" reaction works?


texts: What kind of 'product' is the 'product' in 'ionic product of water'?

texts:
My language has different words for product (=the result of a process) and product (=the sum of multiplied quantities), so I need to know the right meaning to choose the right word.

Which of the meanings above is present in the English term 'ionic product of water' ($K_\mathrm{w}$)?

This definition from http://www.chemguide.co.uk/physical/acidbaseeqia/kw.html seems to suggest it is a sum of multiplied quantities:

  The units of $K_\mathrm{w}$: $K_\mathrm{w}$ is found by multiplying two concentration terms together. Each of these has the units of $\mathrm{mol~dm^{-3}}$. Multiplying $\mathrm{mol~dm^{-3}} \times \mathrm{mol~dm^{-3}}$ gives you the units above.

However, the use of the verb produce in this sentence from https://en.wikipedia.org/wiki/Self-ionization_of_water suggests something that is produced as a result of a process:

  According to the theories of Svante Arrhenius, this must be due to the presence of ions. The ions are produced by the self-ionization reaction $\ce{H2O + H2O <=> H3O+ + OH-}$

Alternatively, could both meanings apply depending on your perspective?

Thanks in advance for any clarification.


texts: Diastereoselective epoxidation of acyclic alkenes with VO(acac)2

texts:
I've been reading about diastereoselective epoxidation of acyclic alkenes with VO(acac)2. This is taken from Carey, Sundberg Advanced Organic Chemistry Part B:

The OH and epoxide are syn.
Then, while reading Smith's Organic Synthesis I've found this (the ratio of products is 5.6:1 in favor of the anti):

which is in contrary with the results from Carey, Sundberg. In an Evans lecture the syn stereoselectivity is explained while in this lecture the anti selectivity is explained. Apparently different sources give opposite selectivities. What is the true explanation here? Is the syn or anti selectivity predominant?


texts: Is the equation below for Gibbs energy only applicable under standard conditions?

texts:
This is quite confusing to me because it seems as if a lot of people use standard state equations and non standard state ones interchangeably:

$$ΔG^\circ = -nFE^\circ$$


texts: Why does osmolarity take into account both penetrating and non-penetrating solutes?

texts:
According to Wikipedia:

… osmolarity takes into account the total concentration of penetrating solutes and non-penetrating solutes, whereas tonicity takes into account the total concentration of non-freely penetrating solutes only.

But if osmolarity has units of $\pu{Osm L^-1},$ shouldn't it include only non-penetrating solutes, because the penetrating solutes won't contribute to the osmoles?


texts: PTFE (Teflon) combined with Silicon Polymers

texts: I wanted to know if it would be possible to combine basic silicon polymers with PTFE in order to create a stable, non reactive silicon rubber that won't react to butane or other hydrocarbons in particular. Is this doable? If so what would it take to accomplish this?


texts: Is it better to use a smaller, more accurate measuring cylinder several times or a larger, less accurate one for the same volume?

texts:
I need to measure out 70 ml of liquid.
I have a 10 ml measuring cylinder with a maximum uncertainty of 0.1 ml and a 100 ml measuring cylinder with a maximum uncertainty of 1 ml.
I've calculated that using the 10 ml cylinder 7 times would give a 0.7 maximum uncertainty, or a 0.7/70=1% percentage uncertainty. Meanwhile, using the 100 ml cylinder, I get a 0.1 ml uncertainty, or a 1/70=1.4% percentage uncertainty. Clearly, the smaller cylinder approach is more accurate (1% < 1.4%)
Meanwhile, the mark scheme says that one must use the 100 ml cylinder, for the 10 ml cylinder would give a total 7*0.1/10=7% percentage uncertainty, compared to the 1.4% from the 100 ml cylinder. (1.4% < 7%)
Isn't adding percentages in this way fallacious? There's no way to accumulate a 4.9 ml error using a 10 ml cylinder 7 times, right? I'd appreciate if someone could clarify which approach is correct and why.


texts: Endo rule and stereoselectivity in the Diels-Alder reaction

texts:
Do you agree with the stereocenter with the $\ce{-CF3}$ and $\ce{-CN}$ substituents in the product?

source

I thought that since $\ce{-CF3}$ is a better electron withdrawing group than $\ce{-CN}$, it would be placed opposite the diene, giving the product in which $\ce{-CF3}$ points up and $\ce{-CN}$ points down.

However, I believe my proposal above is wrong, because probably the substituent with the highest electron-withdrawing property, the $\ce{-CF3}$ should be placed endo because of secondary orbital interactions. Therefore, I expect the product above should be the correct one.

source

When I try to do the endo-product of the following reaction I came to the other syn product with absolute stereochemistry (S,R) instead of the (R,S)-product shown here. So I'm wondering, why we get endo selectivity in the first reaction and exo selectivity here instead.


texts: How to decide the order of stability of allylic carbocations when comparing to benzylic carbocation?

texts:
I was going through my organic notes and found this order of stability of carbocation:
3° benzylic > 2° benzylic > 2° allylic > 3° alkyl
I understand that all this is explained on the basis of combined result of resonance and inductive effect. What if one has to predict these?
For example, if I ask you where will you place 3° allylic and where will you place $\ce{Ph-(CH+)-C=R}?$ How to decide the order in these cases if this kind of question comes up in an exam?


texts: Why does Area of Interface depends on size of particles?

texts:
The interface is usually a few molecules thick but its area depends on the size of the particles of the bulk phases.

*What is  Area of interface? What is its sense and How is it defined.I mean if we have two bulk faces with significant difference in particle size,and we define surface area for one layer then it is surely not the same as that for the other layer then how that area of interface make sense.

One of the explanation (or i should rather say an example) i found on internet is oil dressing on salads ,where interface is spherical having less surface area.

Now that example is itself confusion because it is mathematically proved that for any given volume sphere has least surface area, then how is that area being less attributed to particle size?


texts: Can all NMR spectrometers perform special techniques such as COSY, NOESY, HETCOR,..?

texts:
Do you need special spectrometers for:

probing nuclei other than hydrogen or carbon?
performing 2D spectroscopy such as COSY, NOESY, HETCOR, HSQC,..

Or are these techniques usually available on standard NMR spectrometers?


texts: Structure and oxidation state of bridging complexes

texts:
I am confused about the structure of bridging complexes with the bridging ligands as $\ce{OH-}$ or $\ce{NH2-}.$ Aren't they both monodentate ligands?

And if they form a simple coordinate bond, then the negative charge on them must be lost, but then the oxidation states of the metal atoms doesn't match. For example:

In this compound, please explain what bonds $\ce{OH}$ and $\ce{NH2}$ are actually forming, and the charges on them. Also, how do we find the oxidation state of platinum?


texts: If I mix an aqueous solution of hydrogen chloride with an organic solvent, will the organic solvent contain hydrogen ions?

texts:
For example, let's say I mix $36\ \text{cm}^3$ 2-propanol, $9\ \text{cm}^3$ methyl ethyl ketone and $15\ \text{cm}^3$ hydrochloric acid with a concentration of $1,0\ \text{mol}/\text{dm}^3$.

The hydrochloric acid is solved in water, and since the other compounds are organic and less dense than water they should form two layers. Would the upper layer be "acidic"?

This is an elution I've used in a thin-layer-chromatography lab and I'm trying to figure out what role the hydrochloric acid plays in affecting the compounds' ability to bind to the elution (mobile phase).


texts: What is the name of this molecule? (C₈O₃H₁₃N)

texts:
@tschoppi

Tried taking a stab at this for me and got this much:

1-(1'-oxoethyl)-2-(something-something ester)-pyrolidine


texts: Why should epoxides be more reactive at a position where positive charge is stabilised?

texts:
In the above reaction, I am told that the nucleophilic chloride anion attacks the trisubstituted carbon because it has the most partial positive character due to its ability to stabilize positive charge.

How does that statement make any sense?

I'm not following the train of "logic," which is as follows:

The nucleophile will want to attack the location with the greatest partial positive charge. Okay, Coulomb's law. I'm good with this statement.
The carbon with the greatest partial positive charge is the one that can best stabilize positive charge. (?)
Alkyl groups are slightly electron-donating; the tertiary carbon will be able to better stabilize partial positive charge.
Thus, the chloride anion attacks the tertiary rather than the secondary carbon. I don't see how this follows from the previous assertions. Doesn't stability correspond negatively with reactivity? If so, what is the real reason the chloride anion attacks the tertiary carbon rather than the secondary carbon?


texts: Factors affecting rate of β-elimination reaction with alcoholic KOH

texts:
The question asks for the rate of reaction in $\beta$-elimination using alcoholic $\ce{KOH}$.

Arrange the following alkyl halides in decreasing order of rate of $\beta$-elimination reaction with alcoholic $\ce{KOH}$:
(A) $\ce{CH3-CH(CH3)-CH2Br}$
(B) $\ce{CH3-CH2Br}$
(C) $\ce{CH3-CH2-CH2Br}$

The answer I got was:

B > C > A

The answer given is:

A > C > B

In many sources it is given that the order depends on the stability of the double bond formed, that the more substituted alkene is more stable.
But for alc. $\ce{KOH}$ shouldn't we consider it as an $\mathrm{E2}$ mechanism?
By this I mean, shouldn't the reaction rate depend on the steric hindrances caused by the beta carbon group to the attacking base?
Is this wrong? What would be the correct explanation?


texts: Why are carbonyl compunds more reactive towards catalytic hydrogenation than alkynes and alkenes?

texts:
Alkynes are more reactive towards catalytic hydrogenation than that of alkenes, because they are more unsaturated. This is the correct reasoning, right?
But why are carbonyl compounds more reactive towards catalytic hydrogenation than alkynes? The $\ce{C=O}$ in carbonyl group is polar, but how does that affect reactivity?

Example:

Answer: Option (D), $c>a>b$


texts: Are there any theorems about packing of atoms in molecules subject to the Lennard-Jones potential?

texts:
Related to the problem of minimization of the Lennard-Jones potential in a molecule with $n$ atoms, where $n$ is, say, between $5$ and $10$, questions arise such as (but not limited to) the following:

Is it possible to determine a lower bound on the radius of the molecule?
Is it possible to determine an upper bound on the radius of the molecule?
Is it possible to improve the upper and lower bounds using symmetry considerations?

I consider molecules to consist of point-like atoms, so the radius in question is the smallest radius of a sphere containing all points.

If there are theorems regarding similar questions, that would facilitate determining a reasonable search domain for the optimal configuration.


texts: Are artificial ingredients better than natural ones because they are made in laboratory conditions?

texts:
If we have something like an artificial vanilla flavouring, is it any worse than a natural one?

Will both the natural and artificial ones have the same chemical formula?

Won't the artificial one be purer since its made in lab conditions?


texts:
I tried to balance the following redox reaction

$$\ce{S^0 + OH- -> S^2- + S2O3^2-}$$

by ion electron method, but I am unable to identify the oxidation and reduction half reactions. Please provide the correct method.


texts: How does metallic bonding in alkaline earth metals work?

texts:
Metallic bonds are said to be delocalised.

Lithium crystals have each lithium atom in direct contact with eight other lithium atoms. Each atom could therefore be in a hybrid of eight chemical bonds with each other.

But a similar explanation does not work for atoms like beryllium.

Some possible arrangements of electrons that beryllium could be a hybrid of configurations of might be:

$$\ce{Be^{+} + Be^{-}}$$

$$\ce{Be^{2+}_2 + Be^{2-}_2}$$

$$\ce{Be^+ + e^-}$$

$$\ce{Be^{+}_2 + e^-_}$$

$$\ce{Be^{2+}_2 + 2e^{2-}_}$$

$$\ce{Be^{2+}_2 + e^{2-}_2}$$

$$\ce{Be^{2+}_2 + e^{2-}_2}$$

But beryllium is diamagnetic and all these suggest paramagnetic properties or a $e^{2-}_2$ pair which doesn't seem right to me although I'm not fully sure how the free electron hybrids would work.

Another possibility is that the electrons are dragged up into the p orbitals.

For example, the atoms would have valence electron configurations of:

$$\underset{sp}{[\uparrow \vert \uparrow]} \underset{p}{[\; \vert \; ]}$$

which would result in hybrids of $\ce{Be2}$ or $\ce{Be_4}$ I think.

However, the atoms would have to be dragged up really high so that they aren't paramagnetic.

Let me list out the molecular orbital theory bonding and antibonding orbitals for diberyllium.

$$ \underset{\sigma}{[\uparrow \downarrow]} \underset{\sigma^*}{[\uparrow \downarrow]} \underset{\pi}{[\; \vert \;]} \underset{\sigma}{[\; ]} \underset{\pi^*}{[\; \vert \;]} \underset{\sigma^*}{[\;]}$$

If I wanted a bonding material that was not paramagnetic I'd have to lift up the energy to something like:

$$ \underset{\sigma}{[\uparrow \downarrow]} \underset{\sigma^*}{[\;]} \underset{\pi}{[\; \vert \;]} \underset{\sigma}{[ \uparrow \downarrow]} \underset{\pi^*}{[\; \vert \;]} \underset{\sigma^*}{[\;]}$$

which is probably too high energy to matter for any purposes.


texts: HCl rota-vibrational lab: ab initio simulation of rotation constants

texts:
I'm trying to set up the simulation portion of the classic undergraduate lab studying the rotavibrational spectrum of HCl and DCl. In terms of simulation (using Gaussian 16), the equilibrium geometry and vibrational energy calculations are trivial. Including anharmonicity is also simple through the use of the freq=anharm keyword. I'm running into trouble with the inclusion of vibrational-rotational parameters, which the program is supposed to support, but I can't find appropriate output information. I'm either missing the output data because I don't know what I'm looking for, or something is wrong in the calculation. Specifically, I'd like the students to get ab initio values for $D_e$, $\widetilde{\nu}_0$, $B_e$, and $\alpha_e$ in the following equation ($m$ is a substitution for $-J''$ or $J''+1$ for the $P$ and $R$ branches, respectively):
$$\widetilde{\nu}(m) = \widetilde{\nu}_0 + (2 B_e - 2 \alpha_e) m - \alpha_e m^2 - 4 D_e m^3$$
I'm currently able to find $D_e$ and $\widetilde{\nu}_0$.

The only clue I can find in the calculation is the following lines:

WARNING: Anharmonic treatment of linear tops is experimental.
         Moreover, an hybrid treatment is used to simulate spectra:
         - Energy: equations including degenerate modes are used.
         - Intensity: summation done on N' modes, considering only one mode
           per couple of degenerate modes. No variational correction done.

    ==================================================
                  Coriolis Couplings
    ==================================================
[No Coriolis Coupling for diatomic molecules

Later, in the entry for Vibro-Rot alpha Matrix (where I'd expect to see entries for $\alpha_e$), I get:

Vibro-Rot alpha Matrix (in cm^-1)
---------------------------------
            A(z)        B(x)        C(y)
Q(    1)    -0.00000        NaN        NaN

I'm assuming the message for Coriolis Couplings is connected to the zero-valued alpha matrix. Is there a way to pull out these parameters in a Gaussian simulation? If not, is there another ab initio package that will perform these calculations? I've tried (without luck) to look through the NWChem documentation.

The input might be useful to reproduce the calculation. Unfortunately, the output is larger than SE.com will allow. Let me know if you require additional lines from it (or a full copy).

Input file:

%nproc=4
%mem=400MB
# MP2 def2tzvp
# opt freq=(anharm,vibrot,noraman) scf=tight freq=ReadIsotopes

Vibrational analysis for D35Cl

0   1
 Cl 0.0 0.0 0.0
 H  0.0 0.0 1.27

298.15  1.0
35
2

Update:

After more reading through the Gaussian references, I've found the rotational constants (Ba(x), Ca(y)) under the following section:

     ==================================================
          Vibrational Energies at Anharmonic Level
     ==================================================

 Units: Vibrational energies and rotational constants in cm^-1.
 NOTE: Transition energies are given with respect to the ground state.

 Reference Data
 --------------
                              E(harm)  E(anharm)     Ba(x)      Ca(y)
 Equilibrium Geometry                             10.643785  10.643785
 Ground State                 1525.714  1515.023        NaN        NaN

 Fundamental Bands
 -----------------
     Mode(n)      Status      E(harm)  E(anharm)     Ba(x)      Ca(y)
        1(1)      active      3051.429  2951.452        NaN        NaN

 Overtones
 ---------
     Mode(n)                  E(harm)  E(anharm)     Ba(x)      Ca(y)
        1(2)                  6102.858  5802.928        NaN        NaN

 WARNING: Anharmonic transition moments for symmetric and linear tops
          are not yet fully implemented.

However, I still can't find an entry for $\alpha_e$, the coupling constant between vibrational and rotational states. Is Gaussian capable of putting out this constant? If so, am I looking for it under the wrong name?


texts: Why doesn't pH = pKa1 in the buffer zone for this titration?

texts:
Below is an image from my textbook representing the titration curve for the titration of $5.00\ \mathrm{mL}$ of $0.010\ \mathrm M$ $\ce{H2S2O3}$ with $0.010\ \mathrm M$ $\ce{KOH}$, which has $\mathrm pK_\mathrm{a1} = 0.6$ and $\mathrm pK_\mathrm{a2} = 1.74$.

The Henderson–Hasselbalch equation implies that at the first half equivalence point, $\mathrm{pH} = \mathrm pK_\mathrm{a1}$, and at the second half equivalence point $\mathrm{pH} = \mathrm pK_\mathrm{a2}$, because there are equal changes of the acid and conjugate base.

This means that at the first buffer region b, I should expect the $\mathrm{pH} = \mathrm pK_\mathrm{a1}=0.6$ and at the second buffer region d, I should expect the $\mathrm{pH} = \mathrm pK_\mathrm{a2} = 1.74$. However, this is clearly not the case with the diagram.

What am I missing here? Is it because I have to account for the autoionization of water in the dilute solution? How would I do so?


texts:
When can we say that such metal forms a complex?

Are $\ce{Pd(OAc)2}$ and $\ce{Pd(PPh3)2Cl2}$ complexes?


texts: Anti-adhesive agent for soot particles in the exhuast gas

texts:
I would like to know if there is/are any anti-adhesive agent for the soot particles (soot particles can be considered as the group of carbon particles) i.e., the agent which will prevent two carbon particles sticking togther and leading to agglomeration.

Thank you.


texts: Can anyone please help me how do you determine kinetically the fastest product of sulphonation of $\beta$ napthol?

texts:
I was asked a question in a paper where I was asked to identify the kinetically fastest product of sulphonation of $\beta$ naphthol.

Can anyone please help me how do you determine kinetically the fastest product ??

The answer that is provided was that  the ortho position to the hydroxyl group is the position where the fastest attack would take place. Because when the carbo cation is formed, the most stable one initially.

But I did not find this explanation satisfactory because ultimately the whole molecule is in complete resonance and it should not matter whichever Ortho or para position the sulphonation happens because ultimately the positive charge would end up being stabilised by OH group. Please help me.

The solution argued that this is less kinetically fast as the initial carbocation is less stable. Also there are 2 Ortho positions, but it does not specify which is the faster one.

The solution given was that Oxy Tobias acid is fastest but based on above arguments , R acid is equally likely and Schaeffer's acid is more probable ...(as there is no steric factors

Also what would the thermodynamically most stable product be ??


texts: Effect of +I on the alpha hydrogen in aldol reaction

texts: We have $\ce{(CH3)2CHCHO}$. Is the alpha-hydrogen acidic enough to react with a base? There is +I effect of two methyl groups, however there the carbanion is getting stabilised through resonance. And, as we know that inductive is a weak effect, so will it proceed through aldol reaction or will Cannizzaro reaction occur? Moreover, if we are considering  the inductive effect to be significant,  won't it reduce the electrophilicity of carbon of the carbonyl group, hence reducing the chances of Cannizzaro reaction? What could be the products if the reaction is done separately by using conc. base in one time and dil. base for other?


texts: Phase description for a substance dissolved in a solvent other than water?

texts: I'm trying to write an equation for which I have $\ce{CuI}$ dissolved in acetonitrile. Usually if you have a salt dissolved in water you can denote that using $\ce{(aq)}$, but is there a notation for substances dissolved in a solvent other than water?


texts: Ni-Mh battery makes fizzy sounds while and after charging - why and do I need t replace it?

texts:
I have some Ni-Mh rechargeable batteries (size AA/Mignon 1.2V, 2100 mAh) and just started to charge them using an automatic charger with 450 mA output.

Now one of those batteries surprisingly started to make silent fizzy sounds, like if you're frying something in a pan. It started within seconds after putting it in the charger and keeps going for minutes after removing it from the charger again. There is nothing visible from the outside though, I don't see any bubbles or leaking fluids.

What exactly is the chemical process here that causes this sound (probably something is producing gas) and why does it happen in this one battery and not in the others I have of the same type?
Is that battery still usable (safely?) or do I need to replace it?

Update: As of now, the battery in question is replaced and returned to a recycling station. I'm still interested in the chemical process behind this noise though.


texts:
I would like to increase the density of a given oil (or anything that repels water) so that it is slightly heavier than water; to be able to precisely control how slow the oil would fall in the water.

What can I add to the oil (or the water) to accurately set its density?

I am looking for a cheap solution, that I can easily do at home.

Edit

Another way to create slow and tiny drops would be to drop water into oil. Yet, the oil surface tension prevents water from falling down ; I asked another question for this problem.


texts:
In phenyl carbanion, one carbon atom has a lone pair on it:

This answer claims that the anion is aromatic, because "the lone pair on the benzene is in the plane of the ring and hence orthogonal to the conjugated $\pi$-system so that it cannot interact with it."
Why is the lone pair perpendicular to the plane of the molecule? It seems clear to me that the carbon in question has three $\mathrm{sp^2}$ orbitals, perpendicular to which is a pure $\mathrm{p}$-orbital containing two electrons. Assigning one extra electron (i.e., a negative charge) to an uncharged carbon in a benzene ring shouldn't rotate its $\mathrm{p}$-orbital by $90^\circ$.
The $\mathrm{p}$-orbitals in carbon are, of course, always perpendicular to each other. The $\mathrm{p}$-orbital containing the lone pair should, therefore, be perpendicular to the hybridized orbitals.


texts: I have tried google but without success so here the question: does anybody know a tool that can covert WFN-file to Molden or to Molpro format (including orbital info not the coordinates only).


texts: Rate of dehydration of alcohols having keto group

texts:
The following question was asked in IITJEE-Screening 2000,

Which of the following will be most readily dehydrated in acidic conditions?

I thought that the answer would simply be (c), as its intermediate would be stabilized by resonance with keto group and it is a sec-carbocation (which is common in all the options, so deosn't matter).
But my answer was wrong as per answer key. Am I missing something?

The correct answer as per key was,

 (a)


texts: What aspects of a macromolecule/protein do the various contributions to its entropy relate to?

texts:
I've come across a few different contributions to entropy in macromolecules such as proteins: configurational, conformational and vibrational. The problem is that I can't seem to find a consistent definition and there may be some overlap.

In addition, I've only really understood entropy to be made up of rotational, vibrational and translational components and I'm struggling to reconcile this with the contributions to entropy for proteins described in the literature.


texts:
I'm new here and I'm still learning, I understand that there four rules for aromaticity:

cyclic
conjugated double bonding (every atom in the ring should be sp2)
huckle number should be 2, 6, 10, 14, 18, ..18
planar ring

The 2nd question should be 4 electrons and is antiaromatic, but how about the first question?


texts: Why is the electrode potential of copper positive when hydrogen is more electronegative than copper?

texts: Both copper and zinc has an electronegativity that is smaller than hydrogen, but why does copper have a positive electrode potential while zinc has a negative one? And lead (which has a greater electronegativity than hydrogen) does also have a negative electrode potential.


texts: Unknown glassware please help, vshaped with a small bulb on one side, hollow but narrow to both sides!

texts:
Looking to try an identify some glassware we have found in a cupboard. This is just the start of it...
1 item here, v-shaped, small bulb but hollow, narrow entrance and exit...


texts: Why do electrons jump back after absorbing energy and moving to a higher energy level?

texts: Electrons in a shell absorb energy and move to higher energy levels, but they release their energy and jump back to the shell they originally were in. Why do they jump back? Why can they not keep revolving around the nucleus?


texts:
At the moment, a question puzzling me is why and how glass fibers degrade in water environment? As the degradation of the glass fibers occurs, its reduces the strength of them. As far as I know, the degradation occurs slower in seawater (containing ions) than in distilled water, which in my opinion indicates that process is related to dissociation of glass material.

How does this degradation occur and why is it different for seawater and distilled water? Do I understand correctly, that E-glass is slowly partly dissociating into ions in water environment? Or is it ion-exchange or some other mechanism?


texts:
During a titration lab where 0.1 N of NaOH is added to 20 mL of acetic acid with the same concentration, the equivalence point occurred after adding about 70ish milliliters of NaOH (different peers acquired different values, ranging from 65 mL and 75 mL of NaOH). This completely puzzled me, because after calculating a theoretical titration curve, my equivalence point occurred after adding about 20 mL of NaOH.

My teacher could not explain why this happened, except that acetic acid can act as a buffer – but how do you calculate this and incorporate it into a theoretical titration curve? I just don't understand how 20 mL of acetic acid would require 70 mL of NaOH to neutralise it (both have the same concentration).


texts: I read somewhere that radicals are atoms, molecules or ions that have unpaired electrons, but how do ions have unpaired electrons when an ion has all its electrons paired either by loosing or gaining electrons to attain the nearest noble gas configuration?


texts: What is 'Retention period' in chromatography and what is its importance?

texts:
I heard people quite often speak about retention time/retention period in Chromatography and Mass Spectrometry. I see somewhere that it is the time duration between the injection time and the target compound peak. I have the following questions:

1)What is the purpose of defining that time?

2)If the compound peak is absent, how one can speak about retention time (I mean if the compound completely fragments)?

3)Is it has importance in mass spectrometry as well?


texts: How to calculate the electrochemical potential of Iron(II/III) and saturated calomel electrode?

texts:
Set up an electrochemical cell where the cathode is the system in question B, $\ce{Fe^2+ -> Fe^3+}\ E = 0.68~\textrm{V}$, whereas the anode is a saturated calomel electrode ($0.244~\mathrm{V}$ relative to standard hydrogen electrode). Determine potential of this electrochemical cell.

\begin{align}
\ce{Fe^2+ +e^- &-> Fe^3+} & E &=0.68~\mathrm{V}\\
\ce{2Hg &-> Hg^2+ +2e^- } & E &=0.244~\mathrm{V}
\end{align}

Usually, I just do $\text{Cathode (Fe) - Anode (Hg)}$ and get the correct answer. However, the correct answer is listed as $1.16~\mathrm{V}$. There are only two numbers to manipulate. I found that
$$E(\ce{Fe}) + 2 E(\ce{Hg}) = 0.68~\mathrm{V} + 2\cdot 0.244~\mathrm{V}  = 1.168~\mathrm{V}$$

Why is this? The amount of substance is not supposed to effect the electro-potential.


texts: MDLCT (Connection Table) Format specification

texts: Is there a specification for MDL Connection Table format somewhere. At some places it is mentioned that the format writes the line length as a character then the actual line characters. If I save a structure using ChemDraw, I see no such thing and the lines are separated using CarriageReturn and LineFeed characters. Can someone please point me to the correct format? Is it that the format is different while SAVING TO FILE and while COPYING TO CLIPBOARD?


texts:
Is the correct name for the following structure 3-tert-butylhexane or 3-ethyl-2,2-dimethylhexane?

I think it is 3-tert-butylhexane, but the textbook says it is 3-ethyl-2,2-dimethylhexane. Can someone please explain?


texts: Why isn't carbon-14 included in CIAAW list of isotopic abundances?

texts:
According to Wikipedia, standard atomic weight is based on the published isotopic abundances of CIAAW:

The standard atomic weight $(A_\mathrm{r},$ standard) of a chemical element is the weighted arithmetic mean of the relative atomic masses $(A_\mathrm{r})$ of all isotopes of that element weighted by each isotope's abundance on Earth. The standard atomic weight of each chemical element is determined and published by the Commission on Isotopic Abundances and Atomic Weights (CIAAW) of the International Union of Pure and Applied Chemistry (IUPAC) based on natural, stable, terrestrial sources of the element.

However, this table of isotopic abundances appears to be incomplete — for example, it's missing carbon-14.
Are they only listing primordial isotopes, or maybe those above some threshold of abundance? Is there some other criteria?
Why is carbon-14 not listed?


texts: Does the composition of a solution keep changing when being boiled?

texts: The mole fractions of the components of vapours aren't the same as those of the liquid-liquid solution (unless the solution is azeotropic), this implies a change in the composition of the liquid solution when vapours arise. Consequently, the partial vapour pressures of the components would also change and there would be a messed up cycle. There has to be something that I'm understanding wrongly and I'd like to be told what it is.


texts: Why do compounds with low polarizability occur as gases at room temperature?

texts:
I've read in a textbook that in the fluorine atom, for example, high ionization energy reflects the fact that the electrons are tightly held. Thus compounds containing many fluorine atoms tend to have low polarizabilities, and so the London dispersion interaction is weak. This accounts for the fact that many nonmetal fluorides, such as $\ce{SF6}$, $\ce{PF5}$, and $\ce{IF7}$ occur as gases at room temperature. Even $\ce{UF6}$, despite its high relative molar mass of $\pu{352 g/mol}$, sublimes at only $\pu{57 ^\circ C}$.
I don't really understand why polarizability accounts for the compounds thermodynamic properties. Can someone explain this? Thanks a lot!


texts: Finding the volume of carbon dioxide needed in formation of calcium carbonate

texts:
Carbon dioxide was bubbled into limewater (a solution of calcium hydroxide) and the solid calcium carbonate precipitated was filtered off, dried and weighed. If $\pu{0.50 g}$ of calcium carbonate were formed what volume of carbon dioxide, at room temperature and pressure, was passed into the solution?
$$\ce{Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)}$$

The answer given is $\pu{1200 cm3}$
I solved it like this:
\begin{align}
\\n_\ce{CO2}&=n_\ce{CaCO3}=\frac{0.5}{\pu{100 g}}\tag{1}\\
V_{\ce{CO2}} &=n_\ce{CO2}\cdot\pu{24 dm3} \tag{2}\\
&= n_\ce{CO2}\cdot24\cdot\pu{1000 cm^3} \tag{3}\\
\implies V_\ce{CO2}&= \pu{120 cm3}
\end{align}
Why is my answer wrong?


texts:
This is a semiconductor-related question, but in order to understand the acceptor level energy state of boron in bilicon, I figured I'd ask here for hints.
Boron is a p-type material when introduced in a semiconductor like silicon. Boron forms three covalent bonds with silicon, leaving one silicon atom frustrated, not forming a bond. This doping process introduces the idea of the hole, that is, absence of electron.
However, my chemistry knowledge is limited, and I don’t understand what kind of bond exists when an adjacent silicon valence electron jumps in this electron vacancy. Is this new electron now shared by both silicon and boron, or does it belong to silicon, since silicon complies to the octet rule, whereas boron does not?
Why does the acceptor level reside above the silicon valence band edge and what does this level exactly represent? Does it represent the energy needed for an adjacent silicon valence electron to jump into this vacancy?

Image source: National Schools' Observatory


texts: Why does sodium react with water to produce a hydroxide, while zinc produces an oxide?

texts:
Sodium belongs to the so-called active metals and produces a hydroxide on contact with water. Zinc produces an oxide. Why is it so?

I was given a hint: to read up about electrochemical series. I've read about it, and naturally zinc is way below sodium in the series. Sodium is more enthusiastic about giving away its electrons and forming positive ions.

Zinc is slightly below this bolded line in the series, but I'm afraid I do not fully understand what that means. "Hydrogen gas bubbled through an alkaline solution, shedding two electrons to produce water and neutralize the solution"?


texts: How can I specify pyridine as a substituent?

texts:
You know how when you carry out a reaction with many compounds, when drawing the reactions you just draw a line at a right angle to the bond with a 'R' at the end (see image)?

Then you can specify what group R is in a table (eg: $\ce{OMe}$). However, if instead of adding a substituent to a benzene ring, you have pyridine? How can you specify it?


texts:
I know this might be a silly question but I am confused with different answers of internet. My question is:

Molar conductivity is given as:

Molar conductivity = $\frac{\kappa}{M}$.

S.I. unit of :
$\kappa$ is $\pu{Sm}^{-1}$  &

$M$ is in $\mathrm{mol \, m^{-3}}$.

Thus, Molar conductivity in S.I. is
$\mathrm{S \, m^2 \, mol^{-1}} \tag{1}$

When I substitute
1 m = 100 cm in (1).
I got new unit as
$[\mathrm{S \, cm^2 \, mol^{-1}}] \times10^4$.
But in a book It was given as

$[\mathrm{S \, cm^2 \, mol^{-1}}]  \times 10^3 \tag{2}$

where they have taken S in S/cm and molarity in mol/litre. But where I was wrong.

If you feel the question too confusing just explain me How I can convert that SI unit given in (1) into unit given in (2).


texts:
How to determine order of nucleophilicity among commonly used nucleophiles? For example, in Finklestein reaction, $\ce{NaI}$ (reagent) - taken in acetone (solvent) - displaces $\ce{SH-}$ ion from alkyl group via SN2 mechanism to form an alkyl iodide. But in a separate question we may be asked to write the product formed when $\ce{NaSH}$ reacts with an alkyl iodide in the presence of acetone. Since I do not know which of the two is a stronger nucleophile, I will displace $\ce{I-}$ and form $\ce{alkyl-SH}$. But definitely only one of the reactions shall occur.

So, my question is that is there an order of strength of nucleophilicity (like a metal reactivity series)? I am preparing for JEE Advanced 2015 (college entrance exam in India), so I am expecting answers within its scope.


texts: Why not to consider hydrogen and oxygen moles to determine an empirical formula

texts:
A question says:

Find the empirical formula of an organic compound from the following composition:

34.62% C, 3.88% H, 61.50% O.

The answer is $\ce{C3H4O4}$.
It was found by using the mass (percentages) divided by the molar mass of each element.

But they didn't consider the (2moles) of hydrogen and oxygen in calculations. Why?
in this case it will be $\ce{CH3O3}$

On the other hand, in a similar question in the text book, they consider the moles of hydrogen and oxygen in calculations by multiplying by 2 after getting the moles.

Could anybody explain?


texts: What is the relationship between entropy and heat capacity?

texts:
The molar heat capacity of hydrogen gas and deuterium gas are nearly the same, $\pu{28.8 J K-1 mol-1}$ and $\pu{29.2 J K-1 mol-1}$, respectively, but the absolute entropy of deuterium ($\pu{145.0 J K-1 mol-1}$) is significantly larger than that of hydrogen ($\pu{130.7 J K-1 mol-1}$).
I have seen the equation that associates the heat capacity to entropy, and I understand the equipartition theorem and different modes of motion contribute to the heat capacities. Since the heat capacities are fairly the same, what other factors can affect the entropy in these species?


texts: How does the Mosher ester method allow determination of absolute configuration of secondary alcohols

texts:
One of the challenges in synthesis is the correct assignment of absolute stereochemistry. This has been asked previously on chem.SE (here and here), but this question specifically asks about the determination of hydroxyl stereocentres using the Mosher ester analysis.

Depending on the type of reaction carried out, this can often be done by inspection (for example, if a reaction forms a pair of diasteromers, they are often easily distinguished by NMR, assuming you know the stereochemistry of the initial stereocentre).

Where no chiral centres were previously present in the molecule (or where pre-existing chiral centres are too remote from the new centre to be relevant), assignment of absolute configuration can be challenging. Whilst x-ray crystallography can be used, many small molecules do not crystallise (or at least not without a significant amount of effort).

One method for assignment of absolute stereochemistry of newly formed hydroxyl centres is the Mosher ester analysis, which works by forming a pair of diastereomeric esters, the NMR shifts of which can be used to determine absolute stereochemistry.

How does this method work? There are many diasteromeric esters that could be formed, yet only a specific few are used for this purpose, and equally, how come there is a need to form both diasteromers of the Mosher esters, when the change in shifts could be observed by just forming a single diasteromer.


texts: The product of the reaction of chloroiodoalkane and cyanide ion in acetone

texts:
What would be the product of the following reaction $\ce{Cl-CH2-CH2-CH2-I + KCN} $ ($\pu{1mol}$ each) in acetone?

I think the  reaction should follow the second order nucleophilic substitution mechanism due to primary halide and strong nucleophile. Thus, iodine atom should be replaced giving $\ce{Cl-CH2-CH2-CH2-CN}$ as product but the book says the product is $\ce{I-CH2-CH2-CH2-CN}$. Where am I wrong?


texts: Hazards of Keeping Freshwater Fish in a Container that was Used for Adipic Acid

texts:
I have an Intermediate Bulk Container (IBC) which is a large 3' x 3'x 3' plastic cube. The label on the container described it as storing Adipic Acid.

Is it safe to use this container to grow plant life and harvest fish life for aquaponics? Or is there a possibility that this acid has leached into the plastic?

My quick research has shown that adipic acid is a mild skin irritant.


texts:
In the first stage of the reaction i am confused in which place will the SN2 happen (we have aprotic polar solvent and 4 leaving groups). In my opinion SN2 will happen either to the carbon with F- attached or the carbon with $\ce{Br-}$, $\ce{MeSO3}$ attached as these are the primary carbons. The leaving group strength is $\ce{F- < MeSO3 < Br-}$ so I suppose the  Br will be substituted. The thing is that the nucleophile must attack from 180 degrees direction and I think steric hindrance in this carbon is bigger than the one with $\ce{F-}$. Another factor is that the oxygen atom from $\ce{MeSO3}$ can stabilize the intermediate with resonance.

$\ce{NaH (H^-)}$ activates the  nucleophile by taking the most acidic proton from $\ce{-SH}$. So I think compound X will be:

Then E2 will occur ($\ce{NEt3}$ strong base) and the leaving group will be $\ce{MeSO3}$ (best LG). forming Z :

Is my solution correct?


texts: Solubility of succinic acid in water vs ethyl acetate?

texts:
Today I completed an organic lab practical test about discontinuous extraction. I had to extract succinic acid from a water solution using ethyl acetate as the solvent extractor.
After the extraction, I calculated the partition coefficientto be 0.3.
So, succinic acid is more soluble in water than ethyl acetate, but why?

Does it have to do with the ionization of the succinic in water that may not be possible in ethyl acetate or its related to the intermolecular interations?


texts:
The production of silver ions in Tollen's test violates Werner's theory of
non - ionizable secondary valency since we are using the diamminesilver(I) complex as the reagent. How does one reason this??


texts: After performing both simple and fractional distillations for a 50/50 mixture of methyl acetate/ethanol, i discovered that my total recovery (in mass) of substances after distillation was lower for the fractional distillation than for the simple distillation. Is this to be expected, or would it be because of an error on my behalf? (To clarify, my initial mass for F. distillation was 17.39g and my recovered mass was 14.95g. My initial mass for S. distillation was 16.54g and my recovered mass was 16.04g.) What would be some reasons in explaining this result?


texts: In a sample of radioactive substance all the atoms don't disintegrate simultaneously. Why?

texts: Radioactivity though spontaneous all the atoms don't disintegrate at a time


texts: How can rotamers of alpha-keto esters be named to distinguish between different geometries?

texts:
When talking about free rotation it is often helpful to determine about which geometric arrangement one is referring to. For example in the case of butane we talk about several eclipsed or staggered conformations when discussing the rotational barriers. This also often helps to explain the all trans (staggered) arrangement of fatty acids and surfactants.

In a wider sense even the pseudo rotation of cyclohexane has its own terminology, with boat, chair and twisted conformations.

I am interested in a way to name the two rotamers that can be thought of in α-keto esters (1, 2). My initial thought was calling these cis- and trans- configuration, in analogy of the partial double bond (blue, 3, 4), but for my taste this has a too rigid connotation. Has there been anything proposed in this area? Amides would also be comparable (5, 6).


texts:
Why is the methoxide ($\ce{CH_{3}O^{-}}$) anion negatively charged?

It has 13 valence electrons and has 13 free electrons. In spite of that the methoxide anion is negatively charged.


texts: Vinegar seems to kill poison ivy or at least severely stunt their leaves. I am trying to increase the concentration of acetic acid and I put a bottle of vinegar in the freezer. I have looked at it and it has turned cloudy. I'm thinking if I poured this through a coffee filter I should be filtering out solid acetic acid. I might do this in the freezer because it might take some time. Does anyone think this will work? I might be getting water ice instead. Either way I would be separating the two. I could repeat this step and concentrate it further. Would I not really be filtering out anything? On another blog someone suggested buying aluminum acetate which has more acetic in it instead, but this might not be as effective.


texts: Confusion with usage of heat capacity in Adiabatic expansion

texts:
My book says, that if a system is expanding adiabatically then $dq=0$ and $U= q+w$, so $U=w$.

It also states that $$\delta U=(C_v)\cdot\delta T$$

Here $C_v$, is the molar heat capacity at constant volume. How can they just $C_v$, which is defined for a specific volume, in a system that is expanding, i.e. its volume is changing?


texts: Good summary of highschool to university chemistry

texts:
DISCLAIMER: I've browsed similar questions, but sadly they refer to books that're either too basic or too specialized.

Hello. I'm studying mechanical engineering (1st year), and we have to do a module in chemistry. It's mostly highschool chemistry (equilibrium, redox reactions, acids and bases, ...) with small snippets from unknown topics, such as thermodynamics and crystal structures. We are now beginning with "the chemistry of non-metals", and will eventually cover "the basics of organic chemistry" and "the chemistry of metals and solids". The problem is, we've gotten a new professor who's awful as an educator: he barely speeks the language, and never prepares the lessons. Instead, he just clicks through powerpoint presentations, slowly reading them out, while facing the screen.

I've found that - although more productive than his "lessons" - just reading the presentations is not enough. I recognize what I already know, but require an unreasonable ammount of time to understand the rest, which usually involves browsing wikipedia.

That's why I'd like to ask if anyone could suggest a book that summerizes highschool chemistry, and ventures into topics above highschool level in a way someone with a highschool education would understand. Obviously, alternative mediums such as videos are also fine. I just want something that more or less complements the lectures, and can always just google whatever details are not covered.

Thank you in advance.


texts: How does critical temperature affect adsorption?

texts:
I don't really understand how does a high critical temperature favour adsorption?

What I think is that the lower the temperature, more easy is it for the gas to liquefy and therefore adsorption is favoured


texts: Can anyone explain the shapes of ionic compounds?  What does it mean? What does the coordinate number mean? I know that in $\ce{NaCl}$, one $\ce{Na}$ atom is surrounded by 6 $\ce{Cl}$ atoms, and vice versa, but can it be explained with the help of coordinate numbers?


texts:
Suppose we had a closed system proceeding according to,

$$\ce A +2\ce B \rightleftharpoons 2 \ce C$$

And that three experiments produced the following concentration data.

Experiment 1:

\begin{array}{|c|c|} \hline
{\rm \small Species} & {\rm \small concentration} \\\hline
\ce A & 0.500\rm~M \\
\ce B & 0.700\rm~M \\
\ce C & 0.900\rm~M
\\\hline\end{array}

Experiment 2:

\begin{array}{|c|c|} \hline
{\rm \small Species} & {\rm \small concentration} \\\hline
\ce A & 0.300\rm~M \\
\ce B & 0.420\rm~M \\
\ce C & 0.424\rm~M \\\hline
\end{array}

Experiment 3:

\begin{array}{|c|c|} \hline
{\rm \small Species} & {\rm \small concentration} \\\hline
\ce A & 1.40\rm~M \\
\ce B & {x}\rm~M  \\
\ce C & 1.49\rm~M \\\hline
\end{array}

How would you find the concentration of $\ce B$ from experiment 3 at equilibrium?

I assumed that each experiment was in equilibrium so that I could do the following,

$$K_c = \frac{\ce{[C]}^2}{[\ce{A}][\ce{B}]^2} = \frac{[0.900]^2}{[0.500][0.700]^2}$$

$$\therefore \frac{\ce{[C]}^2}{\ce{[A][B]}^2} = \frac{[0.900]^2}{[0.500][0.700]^2}$$

$$\therefore \ce{[B]} = \sqrt\frac{[1.490]^2[0.500][0.700]^2}{[0.900]^2[0.140]}$$

$$\therefore \ce{[B]} = 2.19\rm~M$$

However, $[\ce{B}] = 2.19\rm~M$ is not the answer. Could someone please provide some insight and direction into this question?


texts: Can we predict the IMF strength of Acetone vs Glycerol?

texts:
I was recently assigned a lab where I was to observe several properties of the chemicals Acetone and Glycerol then use my observations to predict their overall Intermolecular Force strength.
The properties I observed were:
Surface Tension: Here, I found that Acetone had a much higher surface tension than Glycerol. (I tested this by seeing how many drops of each substance would stay on a penny: Acetone had 19 and Glycerol had 13)
Viscosity: Here, I found that Glycerol had a much higher viscosity than Acetone. (I did this by dropping a penny through a 500mL graduated cylinder: Took 0.4 seconds for Acetone and 5ish seconds for Glycerol)
Boiling Point: Researching online, I found that Glycerol had a much higher boiling point than Acetone.
Glycerol also took much longer than Acetone to evaporate.
However, this seems to be conflicting evidence. I have learned that a higher surface tension is associated with overall stronger IMFs (suggesting that Acetone has stronger IMFs), but the other pieces of evidence seem to suggest that Glycerol has stronger IMFs.
My question is, can anybody tell me if Acetone's IMFs really are stronger than Glycerol, or is it the other way around? Additionally, if any of my experimental results seem wrong, can somebody please point them out?


texts: How can I synthesize phenylpiracetam from styrene or benzaldehyde?

texts:
I am trying to design a proper synthesis route for phenylpiracetam.

I am thinking a good starting material would be styrene or benzaldehyde. Here is my proposed route.

Is there a better method? Please identify any mistakes I may have made in my synthesis and suggest improvements, even if you have a different synthesis route in mind.


texts:
I recently stumbled across the substance "p,p′-terphenyldicarboxylic acid" in a scientific journal when recently reading about metal–organic frameworks.

Could someone explain the prefix p,p'- to me?


texts:
I want to learn chemistry. I did not have the benefit of studying it when I was in highschool, and I was always intimidated by it (I feel it's more rote memorization rather than understanding - I'm more of a Physics and Math kinda guy).

Anyway, what are the concepts that I need to learn?

How, and what resources are you going to use to homeschool Chemistry to a teenager?

In that studying it would put the student on par with a normal highschool student.

Some Nice Stuff:

Topics for a Normal Highschool Chemistry Curriculum
and Maybe AP and Honors Program Curriculums?
Comprehensive Textbooks
Exams and Self Testing Resources


texts: Why does ethanol have a health rating of [2] in NFPA 704 whereas methanol, which is far more toxic, has a rating of only [1]?

texts:
Why Ethanol has the blue health hazard rating of 2 in NFPA 704 where as both Acetone and Methanol which are far more toxic than Ethanol have a rating of only 1?    (Click on each link to see the NFPA diamond)

Ethanol
Methanol
Acetone


texts:
I know that a functional group gives definitive property to an organic compund.
But my text book claims carboxylic acid is a functional group but isnt carboxyl the functional group with a formula -COOH , is the text book wrong or am i missing something?
And similarly isnt hydroxyl the functional group of alcohols rather than alcohol being the functional group.
Could you please clear this out ?


texts: R,S in Cyclic Compounds - Path of Highest Priority?

texts:
Consider (R)-3-bromo-1,1-dimethylcyclohexane.

I wish to clarify how I assign R,S priorities in a cyclic compound. My book says to compare the atoms along the "path of higher priority." The problem is in a cyclic compound, if you go far along this path of higher priority without finding a point of difference, you may collide (picture below):

I'm assuming that because the path taken initially results in no difference, we can still assign the top path a higher priority than the lower path because the top path has two methyl groups. My book says that if the paths are identical then choose the one with more of the same atoms.


texts: I have been told that when $\Delta V=0$, work done will be zero $(W=0)$. I know that, in cyclic process $\Delta V$ will be zero, since it's a path function and $\mid W \mid$ i.e. magnitude of work done will be the area enclosed by the curve. But my doubt is when $\Delta V=0$, shouldn't $W$ also be zero in such processes?


texts: Side chain formation in polymerisation of ethylene

texts:
I am having difficulty understanding (or at least need confirmation of my understanding) of this diagram regarding the formation of sidechains of polyethylene. If someone could explain it, that would be great :). Also, what do the rotation symbols mean? Below I include my understanding of the reaction.

My understanding is that the chain terminates with a carbon with an extra bond available. It covalently bonds to a hydrogen from back in the chain, thus forming a complete carbon (connected to the carbon before, and 3 hydrogens).

The group it stole the hydrogen from now becomes a carbon with a missing hydrogen, with an extra bond to fill. Therefore that carbon is connected to the carbons on the left and right of it, and missing one hydrogen on the side. Therefore the group should be CH, since it only has 1 hydrogen left after its other one was stolen. Why does the diagram say CH2?

Then, to the best of my understand, an ethylene group attaches to the side with the missing hydrogen, with the carbon filling the hydrogen's place.  Thus the chain can be continued on the side, indefinitely. In option B: butyl side chain, the hydrogen from another part detaches and attaches to the open carbon on the side chain, terminating it, and forcing the original chain to continue.

In option A: what happens? I don't understand. Are the 2 ethyl side chains never ending? If so, how does that happen? How does the second side chain be produced?


texts: Why is iso-octane different from other iso-s?

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While learning nomenclature of organic compounds I found the common  names to be a bit difficult to learn than the IUPAC ones. One of these common name stuff is the iso-,neo-, sec-, etc. So I searched for the ways to differentiate between these on the YouTube and found this video (note that the anchor of the video uses hindi for communication so it might not be intelligible to most people here). To summarize what the anchor said:

Prefix-iso: is used when all carbon atoms except one form a continuous chain.
$$\mathcal {OR}$$
They have a structure like this:

Now in the same video the anchor says that iso-octane is an exception to this rule, as it has the following shape:

Before this came in the video I formed the view that these are just the ways of naming compounds with similar structure but now I think that that isn't the case. So:

Why iso-octane has shape different than the other iso-s?

The anchor says that the structure of iso-octane was determined experimentally. This implies that there is some way to identify these compounds without knowing their structures beforehand so:

How do we know that whether some given compound is iso-, neo-, etc?

What might be the most general guidance for using iso-, neo-, sec- and tert- prefixes?


texts: What does the "N" in N-nitrosoamine mean/stand for?  Also, if the functional group is connected to a benzene ring what do I call it?


texts: Ring currents of anti-aromatic and aromatic systems

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Why are ring currents associated with aromatic systems diamagnetic while those of anti-aromatic systems are paramagnetic?
Does it have anything to do with the number of delocalised electrons 4n+2 and 4n , respectively?


texts: Is possible to figure out if a battery is NiCd or NiMH?

texts: Aside from opening it of course. I'm not sure if this is the right place to ask this but I have a rechargeable battery pack for an Xbox One controller and the info on it says that it's a sealed nickel cadmium battery but it also has a recycle symbol with "NI-MH" written underneath. The company's website doesn't seem to have any customer support and I tweeted at them on Twitter but haven't received a response. If it is NiCd, I'm surprised that any batteries of that type are still made. If it were Ni-MH I'm sure they would say it on the packaging. I think I read that NiCd cells don't have a large voltage drop until the end of the charge, so I suppose I could measure that. Does anyone have any suggestions about the battery type or know of a better place I could ask this question?


texts: Oxidation state of metals in complexes with bridging ligands

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How do I find the oxidation number of $\ce{Co}$ in a coordination complex like the
tetraaminecobalt(2) $\mu$-amido $\mu$-oxo tetraamine cobalt(2) ion?

I searched all over the net but can't find it anywhere. Please help!