url stringlengths 64 181 | question_title stringlengths 15 159 | question_text stringlengths 47 17.9k | upvotes int64 -14 183 | answers sequence |
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https://chemistry.stackexchange.com/questions/72968/why-not-simulate-every-particle-properties-and-interactions | Why not simulate every particle properties and interactions? |
Today we have huge computational power (which is even significantly larger with supercomputers). I know that computational chemistry is used sometimes to predict particle properties. As I read on Wikipedia:
>
> Present algorithms in computational chemistry can routinely calculate the properties of molecules that c... | 19 | [
[
"\nForty electrons is *tiny*. Even if we limit ourselves to just the valence electons, cyclohexane already has 36 electrons. Anything drug-like has *way* more electrons that 40. For example, [viagra](https://en.wikipedia.org/wiki/Sildenafil) has 178 valence electrons, and that's not necessarily a \"large\" dr... |
https://chemistry.stackexchange.com/questions/72954/how-did-hypophosphoric-acid-get-its-name | How did hypophosphoric acid get its name? |
Why does hypophosphoric acid has a strange name? My knowledge of inorganic nomenclature tells me that the prefix "per-" should be used with "-ic" acids and the prefix "hypo-" goes with "-ous" acids, which isn't the case here. Why is this so?
Just as part of an additional observation, two other things which I find st... | 3 | [
[
"\nYou are most of the way to the reason yourself:\n\n\n$$\\begin{array}{|c|c|c|}\\hline\n\\text{name} & \\text{formula} & \\text{oxidation number of P}\\\\ \\hline\n\\text{phosphoric} & \\ce{H3PO4} & +5\\\\\n\\text{phosphorous} & \\ce{H3PO3} & +3\\\\\n\\text{hypophosphorous} & \\ce{H3PO2} & +1\\\\ \\hline\n\... |
https://chemistry.stackexchange.com/questions/72950/how-can-i-dilute-13-hydrochloric-acid-to-5 | How can I dilute 13% Hydrochloric Acid to 5%? [closed] |
**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
---
**Homework questions** must demonstrate some effort to understand the underlying concepts. For help asking a good homework question, see: [How do I ask homework questions on Chemistr... | -3 | [
[
"\nIn order not to waste your resources I recommend that you specify the quantity that you need for the upcoming reaction.\n\n\nTo make a diluted quantity of $x$ liters you may use the equation $$c\\_1\\*v\\_1 = c\\_2\\*v\\_2 \\\\ v\\_2 = \\frac{c\\_1\\*v\\_1}{c\\_2} $$\n\n\nWhere $v\\_2$ is the volume that y... |
https://chemistry.stackexchange.com/questions/72947/which-analytical-reagent-can-be-used-to-detect-vinca-alkaloids | Which analytical reagent can be used to detect Vinca alkaloids? |
I am commencing a project on increasing the sensitivity of screening of some bioactive compounds produced as secondary metabolites from the plants! All of its chemical struture is known which is a dimer of vindoline ring connected to a catantine ring through carbon-carbon analysis! However there are no reagents specif... | 1 | [] |
https://chemistry.stackexchange.com/questions/72946/calculating-the-entropy-of-vaporization-at-temperatures-other-than-the-normal-bo | Calculating the entropy of vaporization at temperatures other than the normal boiling point |
I would appreciate if someone could explain why this is so:
To find the entropy of transition at another temperature, we have to break the calculation down into three steps . For example, to find the entropy of vaporization of water at 25 C and 1 bar, imagine that we
1. heat the liquid to its normal boiling point, 100... | 3 | [] |
https://chemistry.stackexchange.com/questions/72942/why-does-nitrous-oxide-have-300-times-the-global-warming-potential-of-co2 | Why does nitrous oxide have 300 times the global warming potential of CO2? |
Both nitrous oxide and carbon dioxide have roughly the same atmospheric lifetime (nitrous oxide slightly longer), so I thought that it would have to do with the infrared absorbance associated with each of them. So I looked at their spectrum. [](https:... | 9 | [
[
"\nThere are two really important properties of N2O that make it such an important greenhouse gas, both of which you have raised in your question but need some clarification. \n\n\n1. Infrared absorption - it's good to think in terms of gaps here. There's a lot of overlap between CO2, CH4 and (a frequently ig... |
https://chemistry.stackexchange.com/questions/72940/can-the-hydride-ion-act-as-a-ligand | Can the hydride ion act as a ligand? |
Hydride ion, as I know is a pretty powerful base, much stronger than hydroxide ion and cannot exist in an aqueous phase.
Can it act as a ligand in coordination compounds? Hydride ion has its electronic configuration as $\mathrm{1s^2}$ in a symmetrical *s* orbital so the tendency to donate a lone pair into a metal at... | 2 | [
[
"\nYes, there are many examples. For instance\n\n\n* The common reducing agents LithAl, $\\ce{LiAlH4}$, and sodium borohydride, $\\ce{NaBH4}$ (last one you might argue about)\n* $\\ce{[ReH9]^{2-}}$, see <https://en.wikipedia.org/wiki/Potassium_nonahydridorhenate>\n* Metal carbonyl hydrides, see <https://en.wi... |
https://chemistry.stackexchange.com/questions/72938/is-it-possible-to-determine-the-age-of-a-building-by-just-looking-at-its-window | Is it possible to determine the age of a building by just looking at its window? |
I've recently come across the fact that glass is an amorphous solid and is known as a pseudo solid or a super cooled liquid. Our teacher told us that buildings that if we were to closely observe the glass in the window panes, we would find that it's thicker at the bottom. I'm now wondering if we can calculate the diff... | 2 | [
[
"\nThis is but an urban legend. Glass does not get thicker at the bottom. (Sure, glass **is** fluid to some tiny extent, and it can be demonstrated, but not in this way.) It is just that the glass panes were initially manufactured with uneven thickness. Then the people who stuck the glass into the frames woul... |
https://chemistry.stackexchange.com/questions/72937/what-is-the-meaning-of-n-pr-and-i-pr | What is the meaning of n-Pr and i-Pr? |
Apologies in advance, I have a background in physics, so this question might seem awfully simple.
Anyway, I am interested in the chiral spin selectivity effect in organic molecules, and have read a paper in which they synthesize helicene molecules with side groups R = *n*-Pr, *i*-Pr with absolutely no reference *onl... | 1 | [
[
"\n[Propyl](https://en.wikipedia.org/wiki/Propyl_group) is a simple hydrocarbon with three carbons in it. [Propane](https://en.wikipedia.org/wiki/Propane) is $\\ce{CH3CH2CH3}$.\n\n\nPropyl is the unit formed by attaching that chain to something else (which implies replacing one of the carbons with another bon... |
https://chemistry.stackexchange.com/questions/72931/why-wont-my-propane-combust-when-i-spark-it | Why won't my propane combust when I spark it? |
I need to run an experiment and have some pretty basic questions. I'm trying to get combustion of propane in a controlled environment. I understand that that looks like this:
$$\ce{C3H8 + 5O2 -> 3CO2 + 4H2O}$$
Meaning I need 5 times more $\ce{O2}$ molecules than $\ce{C3H8}$. But, I want to do this based on the vol... | 2 | [] |
https://chemistry.stackexchange.com/questions/72930/enthalpy-definitions-what-are-their-main-differences | Enthalpy definitions. What are their main differences? |
The definition of enthalpy is properly described in [here](https://chemistry.stackexchange.com/questions/72848/equation-of-enthalpy).
*The principal objective of this question is mainly academic. In order to any students with internet connection can find **a definition and an example** of the **enthalpy concept appl... | 7 | [
[
"\nExplanation of notation:\n\n\n$H$ is the enthalpy of the system.\n\n\n$\\Delta$ means change of, so $\\Delta H$ means change of the enthalpy\n\n\n[](https://i.stack.imgur.com/1U2uns.jpg)\n\n\nThis symbol means standard condition, standard... |
https://chemistry.stackexchange.com/questions/72927/what-would-happen-if-hofmann-bromamide-reaction-is-carried-out-in-br2-and-kod | What would happen if Hofmann bromamide reaction is carried out in Br2 and KOD? |
**What would happen if Hofmann bromamide reaction is carried out in Br2 and KOD ?**
[](https://i.stack.imgur.com/l86MV.png)
I already know the mechanism the question is the water molecules that is attacked by the isocyanide is it already present... | 5 | [
[
"\nThis isn't the most well-thought-out scenario, because if you dissolve $\\ce{KOD}$ in $\\ce{H2O}$ all the deuteriums will be lost immediately anyway.\n\n\n$$\\ce{KOD + H2O <=>> KOH + HOD}$$\n\n\nAssuming that the amount of $\\ce{KOD}$ is much less than the amount of $\\ce{H2O}$ (after all $\\ce{H2O}$ is th... |
https://chemistry.stackexchange.com/questions/72925/which-steps-are-most-critical-in-driving-glycolysis-foward | Which steps are most critical in driving glycolysis foward? |
I'm assuming that the non-reversible steps (1,3,10 on the chart below) in glycolysis are the most critical in driving it forward, but I have a feeling it might be something else. If so, why are they the most critical?
I've been using this chart as a reference.
[![enter image description here](https://i.stack.imgur.... | 4 | [
[
"\nThose steps you mentioned are not merely critical steps, in glycolysis but are however the control points of the process and I would prefer to call them rate controlling steps. There is nevertheless one critical step which is believed to be the first committed step in glycolysis (not really sure if there a... |
https://chemistry.stackexchange.com/questions/72923/what-is-the-molarity-of-a-solution-made-by-dissolving-25-63-grams-of-naphthalene | What is the molarity of a solution made by dissolving 25.63 grams of naphthalene (MM = 128.17g) in 250.0 grams of benzene? [closed] |
**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
---
**Homework questions** must demonstrate some effort to understand the underlying concepts. For help asking a good homework question, see: [How do I ask homework questions on Chemistr... | 1 | [] |
https://chemistry.stackexchange.com/questions/72922/where-is-my-antimony-going | Where is my antimony going? |
I work in a trace metals laboratory operating an ICP-OES. I've been having some trouble with the recovery of antimony in a weak $\ce{HCl}$ solution post-digestion.
The antimony is part of a mix of elements in ~$\ce{5\% HNO3}$, 1 mL of which is added to a beaker with ~$\pu{50 mL}$ of $\ce{0.5N HCl}$, then heated at a... | 5 | [] |
https://chemistry.stackexchange.com/questions/72917/sodium-silicide-nasi-synthesis-reversability | Sodium Silicide (NaSi) Synthesis, Reversability |
I'm trying to understand a) the reaction that would produce $\ce{NaSi}$ from $\ce{Na}$ and $\ce{Si}$, as well as how to reverse the reaction of $\ce{NaSi}$ with $\ce{H2O}$. The product of the latter would be $\ce{Na2Si2O}$ (aq), and I want to understand the reaction which would transform it back to $\ce{NaSi}$ (includ... | 0 | [
[
"\nThe reaction of $\\ce{NaSi}$ with water is both highly enthalpically and entropically favored—the reaction produces 5 molecules of $\\ce{H2}$ gas for every 2 $\\ce{NaSi}$ molecules that react, and the enthalpy of reaction is –175 $\\mathrm{kJ\\ mol^{-1}}$. The reverse reaction would require ludicrous amoun... |
https://chemistry.stackexchange.com/questions/72913/solid-state-and-packing | Solid state and packing |
In NaCl there is a simple cubic unit cell and the coordination number is 6. So i am confused how are both the ions arranged in such a lattice, with such a cordination no as in simple cubic unit cell there are 8 atoms on the edge of a cube with a contribution of 1/8 by each of them to each unit cell. Also how does it m... | -1 | [
[
"\nAn unit cell is a periodic structure. There are two types of unit cells: conventional unit cells and primitive unit cells. The conventional unit cell is the one that is used most often. Nevertheless, I suggest that you take a look at what is the difference between the two. There are plenty of resources tha... |
https://chemistry.stackexchange.com/questions/72911/does-the-reaction-of-sulfur-and-potassium-nitrate-involve-production-of-sulfur-t | Does the reaction of sulfur and potassium nitrate involve production of sulfur trioxide? [duplicate] |
**This question already has answers here**:
[What are the reaction products of sulfur and potassium nitrate?](/questions/42800/what-are-the-reaction-products-of-sulfur-and-potassium-nitrate)
(2 answers)
Closed 2 years ago.
I've heard that oxidising sulfur with potassium nitrate yields $\ce{S... | 0 | [
[
"\nIf we talk about the reaction of *only* sulfur and potassium nitrate, then the reaction yields potassium oxide, sulfur dioxide and nitrogen.\n\n\n$$\\ce{4KNO3 + 5S -> 2K2O + 5SO2 + 2N2}$$\n\n\nHowever, when carbon is added in the form of charcoal, then the resulting mixture is called [gunpowder](https://en... |
https://chemistry.stackexchange.com/questions/72909/can-ethanol-be-oxidized-by-hydrogen-peroxide | Can ethanol be oxidized by hydrogen peroxide? |
Is it possible to oxidize ethanol to acetic acid with hydrogen peroxide and if yes then
under what circumstances? I tried it in room temperature but either concentration was too small (of hydrogen peroxide(3%)) or I couldn't quite precisely read the the results of the universal indicator. I also tried heating it up, ... | 9 | [
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"\nFirst things first: Don't mess with higher concentrations of hydrogen peroxide unless you are a trained and well-equipped chemist. We're talking \"steel-reinforced gauntlets\" here. This chemical is as volatile as nitroglycerine.\n\n\nAt 3% you have mostly de-ionized water and for good reason. Hydrogen per... |
https://chemistry.stackexchange.com/questions/72908/relative-energies-of-singlet-and-triplet-states-in-jablonski-diagrams | Relative energies of singlet and triplet states in Jablonski diagrams |
In a Jablonski diagram, we have singlet and triplet excited states where spin is conserved or changed, respectively. My book says any singlet excited state is found to have higher energy than the corresponding triplet state from the same electron configuration. Why is that?
| 4 | [] |
https://chemistry.stackexchange.com/questions/72902/can-we-synthesize-alcohols-by-the-photolysis-of-hydrogen-peroxide | Can we synthesize alcohols by the photolysis of hydrogen peroxide? |
As I was going through my revision of organic chemistry, I came across free radical substitution of alkanes with halogens. In a similar process where we use **hydrogen peroxide**, instead of chlorine, so that photolysis would yield a hydroxide radical $\ce{OH.}$ instead of chlorine radical $\ce{Cl.}$. The rest of the ... | 17 | [
[
"\nI do not believe so.\n\n\nThe mechanism of decomposition of $\\ce{H2O2}$ is:\n\n\n$\\ce{H2O2(g) -> 2HO.(g)}$\n\n\n$\\ce{H2O2(g) + .OH(g) -> H2O(g) + HOO.(g)}$\n\n\n$\\ce{HOO.(g) + .OH(g) -> H2O(g) + O2(g)}$\n\n\n$\\ce{.OH(g), HOO.(g)}$ are both radical compounds. \n\n\nIf you take a look at the first step ... |
https://chemistry.stackexchange.com/questions/72897/gas-liquid-transition | Gas liquid transition |
[](https://i.stack.imgur.com/wcWsU.jpg)
This is isotherm of a real gas is represented as shown in diagram at three temperature . In my book it is written that in ACIH gas liquid transition will involve only one phase throughout .
But I could not ... | 2 | [] |
https://chemistry.stackexchange.com/questions/72894/what-are-the-molecular-requirements-for-condensation-polymerization | What are the molecular requirements for condensation polymerization? |
I know that in order to have addition polymerization, the monomers must have a C=C double bond. However, I don't know the molecular requirements for condensation polymerization. Must the monomers contain a functional group at each and?
Any help is appreciated. Thanks.
| 0 | [
[
"\nMonomers must contain a functional group at each side (at least bifunctional) and these functions have to react with each other (like amine and carboxylic acid to yield amide group or alcohol and carboxylic acid to yield ester group,...) .\n\n\n\n> \n> 1. We can start with two types of monomers that hold i... |
https://chemistry.stackexchange.com/questions/72889/why-only-a-specific-pressure-for-the-habers-process | Why only a specific pressure for the Haber's process? |
This question, in my opinion is different from [Why is the Haber process carried out at such high temperatures?](https://chemistry.stackexchange.com/q/43356/14806)
Referring to the above link, I understand that why high temperature of 700 K is chosen, i.e, to overcome the activation energy barrier as well as kinetic... | 1 | [] |
https://chemistry.stackexchange.com/questions/72886/how-was-it-concluded-that-the-h3o-rather-than-h-is-the-acid-ion | How was it concluded that the H3O+ rather than H+ is the "acid" ion? |
I suspect that initially, scientists believed that the acid ion was $\ce{H^+}$ since $\ce{H2}$ is released through electrolysis, right? But what experiment was done to change the standpoint to assume that it is instead the $\ce{H3O^+}$ ion?
Or perhaps there's both $\ce{H^+}$ and $\ce{H3O^+}$ ions?
| 22 | [
[
"\nActually, the initial theories before Lewis suggested that $\\ce{H+}$ is the cause of acidity. However, it soon turned up that an ion as small as the nucleus of hydrogen (you may simply call it a proton) can't be created in low energy reactions due to its high polarising power. So, $\\ce{H+}$ is though the... |
https://chemistry.stackexchange.com/questions/72885/organic-synthesis | Organic Synthesis |
[](https://i.stack.imgur.com/arwHH.png)
Anybody has any idea how to do this? I tried converting the ketone to a alcohol using Grignard, but I have no idea how to proceed afterwards. I also tried starting with the Wittig reaction by converting to an alkene, but... | -1 | [
[
"\nReact the enolate of pinacolone (t-Bu Methyl ketone) with methyl vinyl ketone. It will first add 1,4 then the resulting enolate will do an aldol on the pinacolone ketone to give 3-tBu-cyclohexenone. React this with Phenyl cuprate and, despite the steric hindrance, it will add Michael-wise to give you the d... |
https://chemistry.stackexchange.com/questions/72882/how-do-i-calculate-the-ph-of-this-buffered-solution | How do I calculate the pH of this buffered solution? |
>
> Calculate the $\mathrm{pH}$ of a buffered solution containing $\pu{0.5 M}$ ammonia and $\pu{0.5 M}$ ammonium chloride when $\pu{0.15 M}$ $\ce{HCl}$ is added into it. The $\mathrm{p}K\_\mathrm{b}$ of ammonia is $4.75$.
>
>
>
This is what I think shoud be going on in the buffer solution:
\begin{align}
\ce{N... | 2 | [
[
"\nYou can think of $\\ce{NH4OH}$ as a hydrate: $\\ce{NH3\\_{(aq)}}$; no need for complicated reactions interconverting the two.\n\n\nConcerning the problem you described, at these concentrations all subtleties are negligible, and you basically only need to calculate the *nominal* concentrations of $\\ce{NH4+... |
https://chemistry.stackexchange.com/questions/72880/is-converting-smarts-to-smiles-a-lossless-operation | Is converting SMARTS to SMILES a "lossless" operation? |
The following three different SMARTS strings represent the same structure - at least when depicting it (e.g. at [Uni Hamburg Smarts viewer](http://smartsview.zbh.uni-hamburg.de/smartsview/view)).
```
SMARTS:
[#6]-1=[#6]-[#6](-[#6]-[#6](-[#6]-1)-[#6])=[#8]
[#6]-1-[#6]=[#6]-[#6](-[#6]-[#6]-1-[#6])=[#8]
[#6]-1-[... | 12 | [
[
"\n[SMARTS](http://www.daylight.com/dayhtml/doc/theory/theory.smarts.html) is deliberately designed to be a superset of SMILES. That is, any valid SMILES depiction should also be a valid SMARTS query, one that will retrieve the very structure that the SMILES string depicts.\n\n\nHowever, as a query language, ... |
https://chemistry.stackexchange.com/questions/72870/finding-out-the-value-of-rate-constant-on-titration | Finding out the value of rate constant on titration |
The question goes as follows
Consider the reaction $$\ce{X(aq) \longrightarrow Y(aq) + Z(aq)}$$
The above reaction is titrated with a reagent $A$ and all of $X, Y, Z$ reacts with $A$ with the ratio of 'n' factors of $X, Y, Z=1:2:3$
here n factor refers to change in oxidation number of substance per mole of the s... | 0 | [
[
"\nFrom a mole balance, we find $C = n\\_x(t) + n\\_y(t) + n\\_z(t) = n\\_x(t) + 2n\\_y(t)$, where the second equality follows from the stoichiometry of the reaction. In particular, our boundary conditions are $C = n\\_x(0) = 2n\\_y(\\infty).$ \n\n\nWe assume that the reaction is first-order, so $n\\_x(t) = n... |
https://chemistry.stackexchange.com/questions/72865/making-artificial-sweat | Making artificial sweat |
I'm currently working on a chemistry investigation wherein I need to dilute a compound with artificial sweat. I have looked at various forums, including [this](https://www.finishing.com/310/79.shtml), which gave answers, but is very outdated.
I have also checked on ISOs standards, but it seems that I cannot get the ... | 0 | [
[
"\nThe international standard ISO 105-E01:2013 *Textiles* – *Tests for colour fastness* – Part E01: *Colour fastness to water* includes specifications for two different solutions:\n\n\n**Alkaline solution,** freshly prepared, using grade 3 water complying with ISO 3696, containing, per litre: \n\n\n* 0.5 g of... |
https://chemistry.stackexchange.com/questions/72862/how-does-vapour-pressure-affect-cooking | How does vapour pressure affect cooking? |
Why should we cover a frying pan with plate while cooking or use pressure cooker? Will it save cooking gas?
| -2 | [
[
"\nWater in the food your trying to cook has a certain boiling point. This boiling point is elevated with increase in pressure (since under high pressure, vapors tend to condense back). To cook the food properly, you'd want the water to stay as liquid as much as possible, even under high temperatures, due to ... |
https://chemistry.stackexchange.com/questions/72849/is-the-amount-of-substance-of-acid-and-base-always-equal-at-the-equivalence-poin | Is the amount of substance of acid and base always equal at the equivalence point? |
Does the amount of substance of acid always have to equal the amount of substance of base at the equivalence point? I know it "works" for monoprotic acids and monobasic bases, but what if we had a diprotic acid and monobasic base?
| 1 | [
[
"\nWe speak in this case of multiple equivalence points. \n\n\nAs a concrete example, if we are titrating $\\ce{H2SO4}$ with $\\ce{NaOH}$, then the first equivalence point occurs when all the $\\ce{H2SO4}$ has reacted to form $\\ce{HSO4-}$, and the second equivalence point when all the $\\ce{HSO4-}$ has furth... |
https://chemistry.stackexchange.com/questions/72848/equation-of-enthalpy | Equation of enthalpy |
This question arises because: by giving classes in thermodynamics, I have observed that students are often confused between the different definitions (or applications) of the enthalpy concept.
The enthalpy expression is obtained as follows:
From the first law of thermodynamics:
\begin{align\*}
U=Q+W
\end{align\... | 3 | [
[
"\n**Definition of internal energy:** U is a function of state, representing the total kinetic and potential energy of the molecules. U = U(T,V)\n\n\n**First Law of Thermodynamics:**$$\\Delta U=\\delta Q+\\delta W$$where the symbol $\\Delta$ is used to represent the change in a (path-independent) function of ... |
https://chemistry.stackexchange.com/questions/72847/2-bromo-1-chloro-4-nitrobenzene-reacts-with-sodium-ethoxide | 2-Bromo-1-chloro-4-nitrobenzene reacts with sodium ethoxide |
What are the major products?
I assumed that their is only one that is possible, which would be replacing the chloro group because the resonance structure supports that one. The bromo group doesn't seem to be able to be replaced. Would adding the ethoxide group, allow for the bromo group to replaced?
| 6 | [
[
"\nThe reaction over here is a $\\text{S}\\_{\\text{N}}(\\text{Ar})$ reaction. Normally, nucleophilic substitutions do not occur, but in presence of strong nucleophiles and electron withdrawing groups, it is possible.\n\n\nNow, coming to your reaction, let's see what really happens:\n\n\nConsider the resonati... |
https://chemistry.stackexchange.com/questions/72846/hcl-and-chrome-plated-plastic | HCl and chrome plated plastic [closed] |
**Closed**. This question needs [details or clarity](/help/closed-questions). It is not currently accepting answers.
---
**Want to improve this question?** Add details and clarify the problem by [editing this post](/posts/72846/edit).
Closed 4 years ago.
[Improve this question](/... | 2 | [] |
https://chemistry.stackexchange.com/questions/72845/what-is-the-ph-of-a-solution-that-results-of-a-mixture-of-two-others-with-known | What is the pH of a solution that results of a mixture of two others with known pH? |
Solution A has a pH of 1, soultion B has a pH of 6. If I mix the same volume V of each solution into one, what will be the pH of the resulting solution?
I'm guessing here as no more information has been provided: It is a mixture of a strong acid with a weaker acid. So I'm assuming that the final concentration of pro... | 1 | [] |
https://chemistry.stackexchange.com/questions/72841/what-is-the-need-for-dipole-moment-if-electronegativity-already-exists | What is the need for dipole moment if electronegativity already exists? |
Say we have an HCl molecule. The difference in electronegativities of the H and Cl atoms tells us how polar the HCl molecule is. The dipole moment is also a measure of the degree of polarity in molecules.
So why do we need the "dipole moment" concept if we can see how polar a molecule is by looking at the electroneg... | 2 | [] |
https://chemistry.stackexchange.com/questions/72838/is-coupled-cluster-variational-for-two-electrons | Is coupled cluster variational for two electrons? |
I know that coupled cluster (CC) is not variational for the general case. However, if we only have two electrons with one nucleus, CCSD should be exact for this system like full configuration interaction (CI). Since full CI is variational, can we argue that CCSD is also variational for this special case?
| 13 | [
[
"\nNo. The reason for this is not to be found in the excitations, but in the evaluation of the method, i.e. the working equations.\n$$%Introducing some shortcuts\n\\require{cancel}\n\\newcommand{\\op}[1]{\\mathrm{#1}} %\\op{H}\n\\newcommand{\\bracket}[2]{\\left\\langle#1\\middle|#2\\right\\rangle}\n\\newcomma... |
https://chemistry.stackexchange.com/questions/72836/difference-between-side-chains-and-functional-groups | Difference between Side Chains and Functional Groups |
From what I've read, a functional group seems to be a **specific case** of a side chain, but this group must be directly responsible for some of the chemical characteristics of the molecule. However, in some cases, methyl groups (such as R-CH3) are listed as functional groups as well. For example, I have the following... | 4 | [
[
"\nSo the example you present is of a poor question. It's a classic case of a \"best answer\" MCQ that requires you pick the answer that is most accurate, rather than an answer that is unambiguously right. (I *hate* these.) Alkanes are listed in most textbooks and guides to organic chemistry as a \"functional... |
https://chemistry.stackexchange.com/questions/72833/is-mgoh2-more-insoluble-than-mgco3 | Is Mg(OH)2 more insoluble than MgCO3? |
In removing temporary hardness by boiling, $\ce{Mg(HCO3)}$ is converted to $\ce{Mg(OH)2}$ but not $\ce{Mg(CO3)}$. The answer that I found in our coursebook was that it has a higher solubility product, but if its solubility product is higher, then it should be more soluble than $\ce{Mg(CO3)}$. Can you tell me the corre... | 17 | [
[
"\nI finally found the answer. \n\n\nIn temporary hardness, we have to remove $\\ce{Mg^2+}$ ions by precipitating it. In $\\ce{Mg(OH)2}$, $\\ce{Mg^2+}$ ions in water are present in the concentration that is cube root of the solubility product, but in $\\ce{Mg(CO3)}$ it is the square root of the solubility pro... |
https://chemistry.stackexchange.com/questions/72829/what-should-be-the-correct-sequence-of-reagents-to-be-used-in-this-reaction | What should be the correct sequence of reagents to be used in this reaction? |
>
> The correct sequence of reagents for the following conversion will be
>
>
> [](https://i.stack.imgur.com/obhcK.jpg)
>
>
> (1) $\ce{CH3MgBr, H+/CH3OH, [Ag(NH3)2]+OH-}$
>
>
> (2) $\ce{CH3MgBr, [Ag(NH3)2]+OH-, H+/CH3OH}$
>
>
> (3) $\ce{[Ag(NH3)2]+OH-, CH... | 3 | [] |
https://chemistry.stackexchange.com/questions/72828/conversion-of-kc-into-kw | Conversion of Kc into Kw |
In deriving the expression for $K\_\mathrm w$, we often start with the equilibrium equation of water
$$\ce{H2O <=> H+ + OH-}$$
The $ \rm K\_c$ expression is quoted as $$K\_\mathrm c = \frac{[\ce{H+}][\ce{OH-}]}{[\ce{H2O}]} $$ followed on by multiplying the $[\ce{H2O}]$ by $K\_\mathrm c$.
The problem I face is I ha... | 1 | [
[
"\n\"The problem I face is I have been taught that the pure liquids aren't included in the expression of $\\mathrm{K}\\_{c}$ since they have a concentration of 1.\"\n\n\nLiquids have a constant concentration (really activity), so in general, it is not helpful to include them in the equilibrium expression. How... |
https://chemistry.stackexchange.com/questions/72825/is-the-ethyl-cation-really-more-stable-than-benzylic-and-allylic-carbocations | Is the ethyl cation really more stable than benzylic and allylic carbocations? |
>
> [](https://i.stack.imgur.com/Sd8Jr.png)
> *Source: Concepts of Organic chemistry by O.P. Tandon, page no. 235*
>
>
>
My book appears to state that the ethyl cation (a primary carbocation) is more stable than both allyl and benzyl carbocatio... | 11 | [
[
"\nI believe this to be a simple typo in the book. In the [original image](https://i.stack.imgur.com/suJ5P.jpg) you'll see that in the surrounding schemes $<$ and $\\to\\text{Stability}$ are given. Only in this line the relations are reversed, while the stability indicator remains the same.\n\n\nHowever, sinc... |
https://chemistry.stackexchange.com/questions/72818/is-chromium-the-shiniest-metal | Is chromium the shiniest metal? |
I have seen many pictures of chromium, and it's pretty lustrous as I must say. Here are some examples. Is it the most lustrous metal known?
Edit: By lustre, I mean suppose if we have a mirror smoothly polished made out of a material, then I consider lustre as the percentage of reflection of light within the waveleng... | 4 | [
[
"\nYou likely refer to remission, especially if you would collect spectroscopic data with an [integration sphere](https://en.wikipedia.org/wiki/Integrating_sphere) at hand. More generally, you refer to [reflectance](https://en.wikipedia.org/wiki/Reflectance), which depends on the material, the selected wavele... |
https://chemistry.stackexchange.com/questions/72814/work-done-by-a-gas-in-thermodynamics | Work done by a gas in thermodynamics |
>
> 23. A given mass of gas expands from state **A** to state **B** by three paths 1, 2, 3 as shown in the figure below.
>
>
> [](https://i.stack.imgur.com/QBF2J.png)
>
>
> If $W\_1,$ $W\_2$ and $W\_3$ are respectively, be the work done by the gas along three pat... | 4 | [
[
"\n[Sign conventions](https://en.wikipedia.org/wiki/Work_(thermodynamics)#Sign_convention) can make 'work' confusing, but the question here asks for the work done *by* the gas. When a gas expands, it's *doing* work (it's *losing* energy), so it's actually $W = + P \\, \\mathrm dV$, inverting all the inequalit... |
https://chemistry.stackexchange.com/questions/72813/using-acidic-detergents | Using acidic detergents |
If detergents were acidic rather than basic, can we still achieve a clean surface? What would be more effective? Strong acid or a weak acid?
How would the result of cleaning be different if an acid of pH 4, for example, is used?
Is it possible to achieve the same result with an acid and a base, or even if they are bo... | 4 | [
[
"\nMany commercial detergents are composed of pH-neutral surfactants like alkyl polyethylene oxides plus alkaline additives like sodium silicate or carbonate or borax, which help dissolve greasy materials better than acids. \n\n\nThere are some acidic detergents, like citric acid cleaners for stainless steel ... |
https://chemistry.stackexchange.com/questions/72811/redox-titrations-half-full-equations | Redox Titrations Half & Full Equations |
I was presented with the following problem and I am finding it difficult to present the half equations for the answers.
[](https://i.stack.imgur.com/nmvpl.jpg)
I managed to produce the half-equation for the Iodine redox.
$\ce{2I- -> I2 + e-}$
I then proc... | 1 | [] |
https://chemistry.stackexchange.com/questions/72810/what-exactly-is-a-solubility-product-and-what-is-its-use | What exactly is a solubility product, and what is its use? |
What exactly is a solubility product, and what is its use?
I've come across this term while reading, and don't have access to anyone who can help me understand this concept.
| 3 | [
[
"\nIf we take small particles of a sparingly soluble salt, say AgCl, then one or two particles may dissolve in water and a saturated solution is obtained pretty soon. Upon adding extra AgCl to the solution precipitation of AgCl starts. At this stage, you'll find an equilibrium is established between the disso... |
https://chemistry.stackexchange.com/questions/72808/comparing-electronegativities-of-aluminium-and-gallium | Comparing electronegativities of aluminium and gallium |
If I were to compare the electronegativities of Al and Ga, shouldn't I be saying that the electronegativity of elements (in general) decreases down the group, I say this by thinking of the position of fluorine amongst the halides and about the metallic character trends (which increases down the group) so Al should be ... | 3 | [] |
https://chemistry.stackexchange.com/questions/72816/what-does-gamma-in-gamma-oryzanol-mean | What does "gamma" in gamma-oryzanol mean? |
The structure of gamma-oryzanol is:
[](https://i.stack.imgur.com/YOelF.png)
What does the "gamma" in its name mean?
| 12 | [
[
"\nNo designations such as alpha-oryzanol, beta-oryzanol, etc. appear to be in use, and according to [this WebMD entry](http://www.webmd.com/vitamins-supplements/ingredientmono-770-gamma%20oryzanol.aspx?activeingredientid=770), as well as [this PubChem document](https://pubchem.ncbi.nlm.nih.gov/compound/64502... |
https://chemistry.stackexchange.com/questions/72807/are-allotropes-of-sulfur-two-different-phases | Are allotropes of sulfur two different phases? |
Monoclinic sulfur and rhombic sulfur are two allotropes of sulfur. In phase equilibria, part of the system that is having distinct boundary, mechanically separable and different chemical or physical properties that other part of the system is considered as a phase. Now I want to ask, do chemical properties of Allotrop... | 1 | [
[
"\nSolid allotropes of pretty much *anything* are different phases. They have different crystal structures, and you can't have a single phase with two different crystal structures inside it.\n\n\nAs for the other criteria, some of them are sufficient but not necessary, and some are difficult to check. The dis... |
https://chemistry.stackexchange.com/questions/72803/why-are-heavy-metal-ions-such-as-those-of-hg-and-cd-toxic-to-animals | Why are heavy metal ions such as those of Hg and Cd toxic to animals? |
Why are heavy metal ions such as those of Hg and Cd toxic to animals?
While studying green chemistry I came to know about the Minamata disease caused by Hg and other disorders due to the accumulation of Hg and Cd so why at all are heavy metals toxic is the reason chemical or biological?
| 1 | [] |
https://chemistry.stackexchange.com/questions/72802/why-copper-wires-submerged-in-salt-or-fresh-water-oxidize-much-faster-while-th | Why copper wires submerged in salt (or fresh) water oxidize much faster while they conduct electrical current? |
On a lot of flooded vehicles (salt/fresh water), I've noticed that wire that carries more current is always the one with most destruction (at the connector/splice), in comparison with lower current carrying wire. Wire turns black on the outer layer, accumulating green/white oxidation(?) on top of it.
How does electr... | 4 | [
[
"\nElectricity in a wire submerged in water effectively turns it into an [electrochemical cell](https://en.wikipedia.org/wiki/Electrochemical_cell), and then it is no surprise that the anode gets oxidized pretty quickly. A modest potential of a few volts would suffice to oxidize any metal, even gold. This wor... |
https://chemistry.stackexchange.com/questions/72799/calculating-volume-in-a-mixture-of-gases-at-equilibrium | Calculating volume % in a mixture of gases at equilibrium |
>
> In a mixture of $\ce{N2}$ and $\ce{H2}$ initially In a mole ratio of $1:3$ at $\ce{30 atm}$ and $\pu{300^\circ C}$, the percentage of ammonia by volume under the equilibrium is $17.8$. I have to calculate the equilibrium constant $K\_\mathrm p$ of the mixture for the reaction
> $$\ce{N2(g) + 3H2(g)<=>2NH3(g)}$... | 0 | [] |
https://chemistry.stackexchange.com/questions/72796/structure-and-bonding-in-clo2 | Hybridisation of ClO2 |
>
> Find the hybridization as well identify the pπ-pπ as well as pπ-dπ bonds in $\ce{ClO2}$.
>
>
>
$\ce{ClO2}$ has 2 $\sigma$ bonds, 1 lone pair, 2π bonds and 1 odd electron.
Hybridisation is equal to number of $\sigma$ bonds + lone pairs. Since we consider odd electron a lone pair like in $\ce{NO2}$ therefor... | 11 | [
[
"\nI actually take issue with the question (which was asked of you not by you), as I think this oversimplifies a molecule, that still isn't well understood in the first place.\n\n\nThat is why I find this question incredibly difficult to answer and why I find that [Nuclear Chemist's answer](https://chemistry.... |
https://chemistry.stackexchange.com/questions/72793/how-to-make-a-primary-alcohol-from-an-alkane | How to make a primary alcohol from an alkane? |
Alcohols can be made from alkyl halides, which can be made from alkanes. However $3° > 2° > 1° > 0°$ for alkyl halides synthesis from alkanes. What approach could make an alkane with primary and secondary carbons into only primary alcohols?
| 4 | [
[
"\nRecently a research paper[[1]](https://doi.org/10.1126/sciadv.abc6688) has been published which claims to effectively convert *n*-alkanes into *n*-alcohols.\n\n\nIt proposes a quadruple relay catalysis for selective synthesis of *n*-alcohols from *n*-alkanes via the following reaction pathway:\n\n\n[![quad... |
https://chemistry.stackexchange.com/questions/72787/relation-between-acidity-and-reactivity | Relation between acidity and reactivity? |
Up till high school, I've been taught that reactivity and acidity of a substance in a relation that if a substance is acidic and if it's acidity is higher (comparatively to some other substance) than its reactivity will also be higher. Examples were mostly given of $\ce{HCl}$ and $\ce{H2SO4}$ stating that since $\ce{H... | 1 | [
[
"\nThe issue is that reactivity is not an inherent property of a compound. It can be reactive towards specific types of reactions and completely inert to others. Acyl chloride reacting with phenol doesn't rely on phenol behaving as an acid, the type of reaction for which you would describe it as more reactive... |
https://chemistry.stackexchange.com/questions/72785/electroplating-an-iphone | Electroplating an iPhone |
I thought it would be cool to electroplate the rear case of an iPhone 6 or newer since it's made out of aluminum. It's been a long time since I learned about the topic, so I looked online to research this, but hardly found anything about the topic other than some aftermarket companies that sell expensive gold electrop... | 0 | [] |
https://chemistry.stackexchange.com/questions/72781/ph-of-0-5m-k2co3 | pH of 0.5M K2CO3 |
$\ce{H2CO3}$ ionises as
\begin{align}
\ce{H2CO3 + H2O &<=> H3O+ + HCO3-} & K\_\mathrm a &= \pu{4.0\*10^{-7}}\\
\ce{HCO3- + H2O &<=> H3O+ + CO3^2-} & K\_\mathrm a &= \pu{5\*10^{-11}}\\
\end{align}
The question is to find out the $\mathrm{pH}$ of $\pu{0.5 M}$ $\ce{K2CO3}$ solution.
Since $\ce{K2CO3}$ is a salt of ... | 2 | [
[
"\nWrite down the actual (equilibrium) reaction that develops between carbonate ion and water when one proton is exchanged (only full-fledged strong acids or bases might exchange a second proton to any significant extent). Which conjugate acid/base appears? $\\ce {H2CO3/HCO3-}$ or $\\ce {HCO3-/CO3^{2-}}$? Whe... |
https://chemistry.stackexchange.com/questions/72778/how-do-stoichiometric-coefficients-effect-the-half-life-of-a-reaction | How do stoichiometric coefficients effect the half-life of a reaction? |
$$\ce{2A -> 3B + C + 2D}$$
This is a first order reaction. Rate constant $k$ for reaction is given to be (say) $\pu{1.386E-2 min^{-1}}$. From this we get the value of $t\_{\frac{1}{2}}$ of reaction as $\frac{\ln(2)}{k} = \pu{50 min}$. Now this $t\_{\frac{1}{2}}$ should mean half life time of reaction (and not for $\... | 3 | [
[
"\nConsider what happens to your argument if I rewrite the equation in the following equivalent form:\n$$\\ce{A -> \\frac{3}{2}B +\\frac{1}{2}C +D}$$\nThat is, you write\n\n\n\n> \n> ... since rate of consumption of A is double the rate of reaction as can be seen from the stoichiometric coefficients\n> \n> \n... |
https://chemistry.stackexchange.com/questions/72775/can-sodium-bicarbonate-be-considered-an-acid | Can sodium bicarbonate be considered an acid? |
I was reading about acids and bases today and finally decided to question the statement that "baking soda is a base."
Let's start with the dissolving of baking soda, $\ce{NaHCO3}$. The equation to represent its dissolution in water is $\ce{NaHCO3 + H2O <=> Na+ + H3O+ + CO3^{-2}}$.
In this "reaction," baking soda ... | 10 | [
[
"\nThe statement you read that \"baking soda is a base\" comes from the fact that a solution of sodium bicarbonate (baking soda) and water has a pH of around $8.3$. \n\n\nHowever, sodium bicarbonate is *amphoteric* with respect to Brønsted–Lowry acid/base theory, which means that it can act as either an acid ... |
https://chemistry.stackexchange.com/questions/72773/how-do-you-draw-nitrogen-in-a-newman-projection | How do you draw nitrogen in a newman projection? |
I have to draw a Newman projection for a molecule, sighting along the bond between a carbon and nitrogen. Given that the nitrogen is behind the carbon from this viewing angle, how would I depict the nitrogen? I know that I cannot draw it as a circle, as that represents carbon, so I am assuming that it is not possible ... | 5 | [
[
"\nIf it were up to me, I would:\n\n\n1. Draw the nitrogen atom as if it were carbon but label it as \"N\".\n2. Assuming normal valence (e.g. an amine but not a nitro conpound), include the formally nonbonded electron pair as one of the substituents on nitrogen.\n\n\n",
"3"
],
[
"\nYou can just dr... |
https://chemistry.stackexchange.com/questions/72768/why-change-in-enthalpy-is-negative | Why change in enthalpy is negative? |
I noticed that the enthalpy of the products of an exothermic reaction (bonds formed are stronger than bonds broken) is lower than the enthalpy of the reactants. Enthalpy equals internal energy plus $PV$. In a constant pressure environment, change in enthalpy equals to change in internal energy as $PV$ in constant. Int... | 2 | [
[
"\nBonds actually have negative potential energy. Think about it this way: in order to break a bond you have to expend energy so when a bond is created, energy must therefore naturally be released. Hence internal energy is lower.\n\n\n",
"3"
],
[
"\n\n```\nWhen stronger bonds are formed, *Ep* is b... |
https://chemistry.stackexchange.com/questions/72765/forming-hydrogen-sulfide-from-electrolysis-of-sodium-thiosulfate | Forming hydrogen sulfide from electrolysis of sodium thiosulfate |
So I was doing electrolysis on two silver electrodes and sodium thiosulfate.
Some observations
* The voltage drops extremely fast from 2 V to less than 1 V in 15 minutes, possibly because of the thiosulfate reduction.
* Gases are liberated out of solution.
* The solution turns black quickly.
Alert: I am using a f... | 1 | [
[
"\nYup, you're forming sulfide.\n\n\nRender the thiosulfate ion as $(\\ce {S-}-\\ce {SO3-})$. Then at the cathode:\n\n\n$(\\ce {S-}-\\ce {SO3-})+2e^- \\rightarrow \\ce {S^{2-}}+\\ce {SO3^{2-}}$\n\n\nBoth products are basic, with sulfide ion being strongly so, and they will react further with protons; so the s... |
https://chemistry.stackexchange.com/questions/72759/does-addition-of-hcl-favour-or-disfavour-formation-of-tetraamminecopperii | Does addition of HCl favour, or disfavour, formation of tetraamminecopper(II)? [closed] |
**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
---
**Homework questions** must demonstrate some effort to understand the underlying concepts. For help asking a good homework question, see: [How do I ask homework questions on Chemistr... | -1 | [
[
"\nHCl reacts with ammonia and removes it from the equilibrium above:\n\n\n$$\\ce{HCl + NH3 <=> NH4+ + Cl-}$$\n\n\ntherefore the equilibrium will shift to the left.\n\n\n",
"4"
]
] |
https://chemistry.stackexchange.com/questions/72748/how-to-prepare-and-store-anisaldehyde-tlc-staining-solution-what-will-be-the-co | How to prepare and store anisaldehyde tlc staining solution? What will be the color of this solution? What is its shelf life? |
I prepared anisaldehyde charring solution, and refrigerated it. Its color was yellow.
However when I am using it for staining tlc plate, it is giving dark pink color on tlc plate surface and unclear blue stains... Also not all the stains are visible. If I am not wrong it should have white background with dark brown sp... | 1 | [
[
"\np-Anisaldehyde (PAA) stain\n==========================\n\n\n[This posting](http://www.ochemonline.com/TLC_stains) from www.ochemonline.com (which is available under a CC-By-SA-3.0 licence) provides the following information about the stain and its behavior. The information below is consistent with my perso... |
https://chemistry.stackexchange.com/questions/72747/precise-explanation-of-macrocyclic-effect | Precise explanation of macrocyclic effect |
In most of the books, the reason of macrocyclic effect is given that It occurs due to preorganised structure of macro-cyclic ligand.
But a proper explanation of these two particular examples isn't given anywhere (even in the book from I've read it).
I've come up with the following explanation -
Cyclam has just a... | 4 | [] |
https://chemistry.stackexchange.com/questions/72746/super-saturated-solutions | Super-saturated solutions |
If a solution is super-saturated is it possible to add a substance to it without allowing it to crystallise? Does a change in temperature have to happen and reduce it's saturation if I want to add another substance?
| 2 | [
[
"\nIt depends on what the solution is saturated with, the degree of supersaturation, and what substance you are adding. \n\n\nIf you are adding more of the substance with which the solution is supersaturated, the addition will likely provide a \"seed\" for nucleation (precipitation of the solid). The same wil... |
https://chemistry.stackexchange.com/questions/72744/nucleophilicty-order-of-various-nucleophiles | Nucleophilicty order of various nucleophiles |
Which one is more nucleophilic in strength $\ce{Br-}$ or $\ce{OH-}$?
I am confused since $\ce{OH-}$ is more electronegative than $\ce{Br-}$ but also a strong base which contradicts for a better nucleophile .
| 0 | [
[
"\nLike most concepts that are not captured by a single number, nucleophilicity is not a simple (or at least, relatively simple) concept like acidity.\n\n\nNucleophilicity depends a lot on orbital alignment and interaction, in addition to thinking about charges. It's also confusing because nucleophility is no... |
https://chemistry.stackexchange.com/questions/72741/why-does-atp-inhibit-glycogen-synthase | Why does ATP inhibit glycogen synthase? |
Why is ATP an inhibitor? I mean, if there are high levels of ATP, it means that the cell has adequate amounts of energy. Therefore, if it doesn't need the energy, then glucose needs not go through glycolysis to produce that energy and is more practical to be stored as glycogen. So why is ATP an inhibitor of glycogen s... | 1 | [
[
"\nFirstly, I will put across main points so that it will be easy to understand this complex control mechanisms of the enzymes involved in both processes:\n\n\n**Glycogen synthase control**\n\n\nControl of glycogen metabolism is effected via reciprocal **regulation of glycogen phosphorylase and glycogen synth... |
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