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9
votes
2answers
27k views

Why does temperature affect cell potential?

The Nernst equation describes the relationship between cell potential and temperature. But why does temperature affect cell potential? My understanding is that the collision model of kinetics is not ...
5
votes
1answer
91 views

Is the subtrahend in the Nernst equation related to ohmic drop?

Let us consider the Nernst equation $$E= E^\circ -\frac{2.303RT}{nF} \log Q$$ which once at $\pu{298.15 K}$, is the equivalent of $$E= E^\circ - \frac{0.059}{n} \log Q .$$ Does the part of the ...
1
vote
1answer
588 views

Solid and Liquid Equilibrium [duplicate]

I understand why solids and liquids are not included in the $K_{eq}$ expressions. However, I'm wondering what the $K$ value for a reaction involving only solid or liquid reactants and products looks ...
9
votes
1answer
239 views

Aromatic ring substitution: how are MNT and DNT further nitrated if nitro groups deactivate benzene rings?

This is probably a common question because it involves TNT precursors, but if an $\ce{NO2}$ group deactivates benzene rings toward electrophilic aromatic substitution reactions, then how can toluene ...
4
votes
2answers
798 views

Why is the volume in this compress gas cylinder constant throughout?

I am stuck on this gas question and its really stressing me out. A compressed cylinder of gas contains $2.25 \cdot 10^3~\mathrm{g}$ of $\ce{N2}$ gas at a pressure of $4.25 \cdot 10^7~\mathrm{Pa}$...
2
votes
1answer
1k views

How can I calculate molality from molarity?

How can we determine the boiling point of 1 molar aqueous solution (density 1.06 g per ml) of KBr? If I use the colligative property formula than I require molality instead of molarity. Here the ...
3
votes
0answers
301 views

How to calculate to actual calcium content in a pudding mix [closed]

How can I determine the calcium (Ca2+ ion) content in pudding mix given the amount of milk, number of servings made with one package, the percent of recommended daily dose of calcium per serving, and ...
1
vote
2answers
1k views

How to represent a 3D model of cocaine?

For my AP Chemistry class we were told to make a molecular diagram that was "better than excellent" and the rest is up to us (we could choose the molecule and how we wanted to represent it). My group ...
4
votes
1answer
665 views

HOMO/LUMO and charge distribution

I am a little bit confused between charge distribution and HOMO/LUMO site in determining chemical reactivity. In charge distribution, the sites which are deficient and abundant in electrons are ...
1
vote
0answers
42 views

Weighted Drilling Fluid Comparison with CaCl₂

I asked a question previously, and the answer was quite illuminating. The answer ushered me forth in a direction that finally made sense. I ended up finding this website, chem.latech.edu/~ramu/cmen522/...
5
votes
2answers
768 views

Which pH indicator will give a dramatic color change with small changes in the amount of carbon dioxide dissolved in water?

I want to do a demonstration for students where they take a capped syringe and change the volume above a solution of seltzer water. The amount of carbon dioxide dissolved will vary, hopefully ...
3
votes
2answers
619 views

Calcination in metallurgical process?

In calcination why is the ore heated in the absence of air in a reverberatory furnace, does the presence of oxygen affect any thing?
4
votes
2answers
4k views

How can pKas differ across similar protons of the same atom?

For example, citric acid has three acidic protons, all of which are carboxylic acids. Despite being part of the same functional groups, they all have very different pKas. Why (and how?) is this?
2
votes
0answers
861 views

How are pressure vessels heated?

I'm working on a project in which I'll be dealing with pressure vessels. As of now I've drawn/conceptualized everything on theory basis. The diagrams are made on the basis of theory, but then I came ...
6
votes
1answer
284 views

Why do people assume 28 oxygens in chlorite mineral formula?

I have been trying to calculate chlorite mineral formulas from microprobe data. However, all of the mineral formula spreadsheets on the internet, including those from the Open University assume 28 ...
18
votes
2answers
4k views

Salts that are more hydrophilic than NaCl

What other, rather easy to obtain, salts are more hydrophilic than $\ce{NaCl}$? Is there a hydrophilic scale for substances like the Mohs scale of mineral hardness?
3
votes
3answers
5k views

Gibbs Free Energy

My teacher said that The decrease in Gibbs free energy is the maximum non-mechanical work that can be obtained when the process occurs reversibly at constant temperature and pressure But for a ...
7
votes
1answer
343 views

No chlorate esters? Why?

Why are there no chlorate esters? Or are they just undocumented or too unstable? I've seen perchlorate esters, but google "chlorate esters" and only perchlorate esters come up.
12
votes
1answer
262 views

How do I synthesize 3-phenyloxirane-2-carbaldehyde from chloroacetonitrile?

How do I synthesize 3-phenyloxirane-2-carbaldehyde from chloroacetonitrile? My proposed route involves: hydrolysis of the nitrile to form a carboxylic acid, and subsequent esterification then, a ...
2
votes
1answer
1k views

Are there ways to fully dissociate a complex salt?

A complex salt is a salt where the metal and ligands do not dissociate in water. For eg : $\space\ce{K_4[Fe(CN)_6]}$ when put into $\space\ce{H_2O}$ dissociates as : $\space\ce{4K^+} + \ce{[Fe(CN)_6]^...
1
vote
1answer
34 views

Determination of a chemical compound in a non-homogeneous sample

I want to know if it is possible to determine a chemical compound in a non-homogeneous sample. I am asking this because we are aiming to create a device that will detect histamine level in fish ...
5
votes
1answer
718 views

Addition reaction of hydroiodic acid to 2-bromo-3-chloro-2-butene

How can the major product of the addition reaction of 2-bromo-3-chloro-2-butene with hydroiodic acid be predicted, since Markovnikov's rule fails to distinguish it? $$\ce{H3C-C(Cl)=C(Br)-CH3~+~HI~-&...
2
votes
1answer
80 views

kinetic and thermodynamic parameters of biodiesel production from lard

I want to know if someone has experimental results and calculations of the kinetic and thermodynamic parameters of Base Catalyzed Transesterification of pig fat, if not which is the method used to ...
2
votes
3answers
486 views

Alkali metal enolates

Why do lithium enolates add to an electrophile in direct addition manner, while the sodium and potassium enolates tend to add in conjugated additions? The sodium and potassium enolates are well ...
1
vote
1answer
75 views

Pressure over a solution

I was wondering something, if I have the same molar fraction for two different substances for a vapor on top of a solution, will this mean that the pressure of each individual substance will be the ...
5
votes
2answers
231 views

Is it possible to combust a plasma?

In what we usually consider combustion your fuel and oxidizer are always neutral, but is it possible to have a similar "explosive" combustion process where both the fuel and oxidizer have been singly ...
12
votes
2answers
7k views

In molecular orbital theory, why does s-p mixing in the dinitrogen molecule not effect the 1σᵤ orbital?

s-p mixing in $\ce{N2}$ causes the $1\sigma _g$ orbital to decrease in energy, the $2 \sigma _g$ orbital to increase in energy (to higher than the $1 \pi _u$) yet the $1 \sigma _u$ is left unchanged ...
4
votes
2answers
932 views

How can the electronic structure of pentaaquanitrosyliron be explained?

The magnetic moment of $\ce{[Fe(H2O)5NO]^2+}$ is 3.87 Bohr magneton, which implies that there are 3 unpaired electrons. Since iron is in $+1$ oxidation state (due to charge transfer with nitrosyl ...
6
votes
1answer
1k views

Are there any magnetic particles that are safe to inhale?

In medicine, there is an (old?) experiment where a subject is asked to inhale radioactive Xenon gas, and radiation counters are placed at different positions near the lungs. Using this experiment, it ...
3
votes
1answer
22k views

What is the temperature of heat generated from LPG gas?

I'm working on a project and I require around 300-400 degree Celsius of temperature. As of now I'm taking the normal LPG gas that is available in our house for cooking purposes for my project, but I'm ...
5
votes
1answer
745 views

How can Nernst equation apply in this redox reaction?

$$\ce{CuSO4 + Zn -> ZnSO4 + Cu}$$ What is the cell potential of the voltaic cell with copper and zinc electrodes if the system is at 50 degrees and the solutions are both at 1 mol? How can it be ...
2
votes
1answer
5k views

The meaning of different parts in the naming of glucose

There are two main types of glucose, $\alpha$-D-(+)-glucose and $\beta$-D-(+)-glucose. Can anyone please explain what is $\alpha$,D or (+)? So (maybe by permutation and combination), how many types ...
0
votes
1answer
172 views

Intramolecular hydrazide condensation

Say I have acetohydrazide ($\ce{CH3CONHNH2}$). Is it possible, that when I add an acid, an intramolecular condensation reaction occurs, forming the cyclic compound 3-methyl-1⁠H-diazirine: ...
8
votes
2answers
4k views

Why are oxime geometrical isomers stable?

231st page of Clayden OC 2nd edition: Unlike the geometrical isomers of alkenes, however, those of an imine usually interconvert quite rapidly at room temperature. The geometrical isomers of ...
8
votes
2answers
3k views

Can I make a buffer from two different weak acids or bases?

Can I make a buffer using two different acids/bases? For example, adding 1 mole of acetic acid and 1 mole of ammonia? The only information I can ever find is that I can make a buffer using only an ...
2
votes
3answers
6k views

Hydrogen fuel cell - why do the H+ ions move through the electrolyte

Consider the following hydrogen fuel cell http://butane.chem.uiuc.edu/pshapley/Enlist/Labs/FuelCellLab/FuelCell.html At the anode, hydrogen is oxidised (losing electrons). My first question is this: ...
3
votes
1answer
9k views

Why does the electron configuration for some elements not follow the diagonal rule?

I'm doing a high-school assignment, and I came across a question that I didn't quite understand. Explain how the electron configurations for the following elements do not follow the diagonal rule: ...
3
votes
1answer
85 views

Is there any abbreviation for hydrates?

I'm getting tired of writing out the full formulas for hydrates, adding $\ce{.$x$\,H2O}$ to all formulas. I'm wondering if there's standard shorthand for these.
0
votes
1answer
65 views

Confused on normallity

So normality is 'equivalents' over liters solution right? I'm having a hard time understanding exactly what an equivalent is. At first from one thing I read i thought it was just the H released from ...
0
votes
0answers
68 views

How is streaming potential measured?

This paper describes the measurement of streaming potential using a potential divider configuration. However it is unclear where the potential difference is created. From the diagram it appears that ...
3
votes
1answer
2k views

Creation and Combustion of Nitrocellulose

I am intending to demonstrate the formation and combustion of nitrocellulose with my high school students, however I am concerned about the potential products of the combustion equation. I have been ...
12
votes
2answers
304 views

What is the meaning of “no Hessian Eigenvalue ”?

When running GAMESS for finding Hessian Eigenvalues and frequencies ( using Optimization with hessian calculation at the end ) , I have seen there are times that it comes out "without any frequencies"....
2
votes
1answer
73 views

An electric potential is generated when a liquid moves with respect to a solid (streaming potential). Is the reverse true?

Streaming potential is an electrochemical phenomenon that a that relates electric currents with the relative movement of solid and liquid phases in contact with each other. So when a liquid moves ...
2
votes
1answer
182 views

pKa vs range in choice of an indicator

When choosing the ideal indicator during a titration, there are two considerations to keep in mind: The pH = pKa of the equivalence point The indicator has a small range (<±1) over which it can ...
5
votes
2answers
326 views

Crystal Lattice Defects

Why do defects in crystal lattices of various molecules and compound occur ? Is it due to the continuous contact or it arises due to impurities and human error during the formation?
3
votes
1answer
1k views

Which is the least stable trihalide of nitrogen?

Which is the least stable trihalide of nitrogen and why? I have two conflicting theories, one is that fluorine-fluorine electron repulsion will make $\ce{NF3}$ least stable and another is steric ...
12
votes
3answers
4k views

Is water a better nucleophile than bromide?

I am a student of biochemistry. My organic chemistry professor was giving a lecture and he talked about halohydrin formation reactions. At one point, he said that "water attacks instead of bromide ...
5
votes
2answers
829 views

Does the compound KFO₃ exist?

As the compound potassium chlorate exists, is there something as $\ce{KFO3}$? All the other halogenates are mentioned somewhere on the web but what about this? If no, then why?
2
votes
0answers
361 views

Why does the definition of ionisation energy only include gaseous atoms? [duplicate]

I know that in physics there is thermionic emission and the photoelectric effect. These are both method of removing electrons. I think these affects are only for metals due to their de-localized ...
4
votes
1answer
2k views

Acid chlorides and reduction by hydrogenation

An acid chloride being reduced through catalytic hydrogenation is an "unobserved" event in the context of our class, according to my professor. Nonetheless, we are expected to predict that the ...

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