The study of chemical systems using the laws and concepts of physics. This usually requires the techniques of thermodynamics, statistical mechanics and quantum mechanics.

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3
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1answer
258 views

Is the Aufbau principle violated in the diagram (b)?

The question is:- In which of the following diagrams is the aufbau principle violated:- I have tried to answer this in the following way:- Now ignoring the Hund principle, the aufbau principle ...
-5
votes
1answer
46 views

What's the magnetic quantum number for p orbitals ? what's for px , what's for py & what's for pz ? please answer them separately [on hold]

please tell me which one is true ? 1. px orbital ----> m = -1 , py orbital ----> m = 0 , pz orbital ----> m = +1 ; OR 2. py orbital ----> m = -1 ; pz orbital ----> m = 0 ; px orbital ----> m = +1 ...
2
votes
2answers
49 views

Equilibrium of more than two inter reacting species

We know that equilibrium in a chemical system is attained when forward and backward reaction rates are equal. What if the reaction mixtures involve more than one reaction? For example, consider three ...
4
votes
0answers
32 views

Water/ethanol mixing problem

In the following question, the water/wine mixing problem was recast in chemical terms. However, partial molar volumes can make this a much more challenging problem than it appears on the surface. ...
5
votes
1answer
58 views

Average or individual molar heat capacity?

In finding enthalpy change $\Delta H$ during adiabatic, reversible expansion of mixture of two ideal gases $n_1$ mol of $\ce{A}$ ($C_{\mathrm{m},v}=\frac{3}{2}R$) and $n_2$ mol of $\ce{B}$ ...
-4
votes
0answers
38 views

Container A and Container B? [closed]

Container A with volume $V$ in temperature $T_1$ contains 3 moles of He gas. Container B with volume $V$ in temperature $T_2$ contains 3 moles of Ar gas. If the root-mean-square speed of the two ...
-2
votes
0answers
21 views

Michaelis-Menten 2 [closed]

In an enzyme-catalyzed reaction that follows the Michaelis-Menten mechanism, calculate the value of the Michaelis constant KM if the forward rate constant k1 is 4.3 × 10^6 L / (mol s), the reverse ...
-4
votes
0answers
27 views

Michaelis-Menten [closed]

At 25 ºC an enzyme accelerates a reaction by a factor of 10^7 over the uncatalyzed reaction in water. If the effect of the enzyme is solely to reduce the energy of the transition state, by what amount ...
2
votes
1answer
42 views

The proper explanation for the general formula of the DU? [duplicate]

I found a formula for the degree of unsaturation (DU) in Clayden’s Organic Chemistry. It explains, simply, the unsaturation with the difference in H atoms. Then I stumbled upon the general formula: ...
0
votes
1answer
30 views

Deviation of real gases from ideal behaviour

From the Amagat's curve we can see two types of result for real gases. If we increase pressure,the value of $PV$ decreases initially and then the value starts increasing for the gases like- carbon ...
3
votes
1answer
31 views

Relation between electric dipole moment and polarization?

Eq. 1: $\space$ $\vec{p}_\text{ind}=\alpha \vec{E} $ The induced dipole moment is the polarizability times the electric field vector. Eq. 2: $\space$ $\vec{P}(\omega) \propto \chi^{(1)}(\omega) ...
3
votes
1answer
53 views

Degree of association, van't hoff factor and dissociation constant

$\ce{CH3COOH->CH3COO- + H+}$ \begin{array}{c|c c c}\mathbf{Initial} & \mathrm{1~mol} & \mathrm{0~mol} & \mathrm{0 ~mol} \\\hline \mathbf{Final} & \mathrm{1-\alpha ...
-1
votes
0answers
25 views

Energy of a system if the nuclear repulsion increases [closed]

I have calculated the optimised geometry for a molecule, $\ce{C5HF7}$. I have noticed that the energy of the nuclear repulsion increases with each iteration of optimisation. What is the logic behind ...
-1
votes
1answer
42 views

Ideal gas in a box and leaked out in vacuum [closed]

an ideal gas is at pressure $P$ and temperature $T$ in a box,which is kept in vacuum with in a large container. the wall of the box is punctured .what happens to temperature as the gas occupy entire ...
0
votes
1answer
23 views

How to write the last cell reaction for the following cell?

Consider the following electrochemical cell: $$\ce{Zn|Zn^{2+}}(0.1~\mathrm{M})||\ce{Zn^{2+}}(0.01~\mathrm{M})\ce{|Zn}$$ How should I write the overall cell reaction for this cell? I can identify the ...
3
votes
2answers
66 views

How can hybrid orbitals be equivalent?

How can hybrid orbitals be equivalent? Take, for example, $\mathrm{sp^3}$ hybridization. The wave functions of each hybrid orbitals are given by: \begin{align} \psi_1 &= \psi_s + \psi_{p_x} + ...
3
votes
2answers
54 views

Bonds and pairing of spins

I was reading Peter Atkins' Elements of Physical Chemistry where I came across this line: Bonds do not form because electrons tend to pair; bonds are allowed to form by the electrons pairing their ...
2
votes
1answer
62 views

How does Aloe Vera leave a cool feeling on your skin? Why does it evaporate fast?

If you have ever grown Aloe Vera and applied it to your skin, it feels a bit slimy. However, after it evaporates it has a cool feeling on your skin. Also, why does the Aloe Vera evaporate so fast? ...
4
votes
1answer
41 views

Why is change in gibbs energy not zero through the gibbs free energy equation?

Change in enthalpy of the system is equal to its temprature multiplied by its change in entropy (as change in enthalpy is equal to heat absorbed /given out at constant pressure and change in entropy ...
6
votes
0answers
76 views

Temperatures Below Absolute Zero

This seems like a farce... http://www.nature.com/news/quantum-gas-goes-below-absolute-zero-1.12146 I have seen several recent articles like this one and I am extremely skeptical. Perhaps my ...
2
votes
2answers
79 views

Why do 3d orbitals have lesser energy than 4s orbitals in transition metals? [duplicate]

This is quoted from Jim Clark's Chemguide For reasons which are too complicated to go into at this level, once you get to scandium, the energy of the 3d orbitals becomes slightly less than that of ...
3
votes
1answer
21 views

Getting the pressure using the equation of states - will the answer be the same?

When I get the pressure using the different equations of state (e.g. van der Waals, Redlich-Kwong, etc.), will the answer still be the same?
3
votes
1answer
30 views

Virial equation of state - Taylor expansion

I don't get how Taylor expansion over $ \frac{1}{\overline{V}} $ of Virial equation of state is caried out: $Z = \frac{P\overline{V}}{RT} $ which yields $$ Z = 1 + \frac{B_{2V}(T)}{\overline{V}} + ...
1
vote
1answer
58 views

Which temprature is taken in Gibbs free energy equation, of the system or the surrounding? [duplicate]

Which temprature is taken, the temprature of the system or the temprature of the surrounding? I think it should be the temprature of the surrounding. This is because if we take the temprature of the ...
5
votes
2answers
209 views

How many coordinates should be used for the potential energy surface of a non-rotating linear molecule? (3N-6) or (3N-5)?

Take, for example, CO$_2$. It is pretty clear that in the absence of rotation, the energy of this system depends only on the two bond lengths and the bond angle. So if I wanted to build a ...
4
votes
1answer
50 views

Palladium Nanocube

What is the relative permittivity and relative permeability of a palladium nanocube? If I change the size of this $\ce{Pd}$ nanocube, will these values be changed or remain the same?
13
votes
1answer
99 views

Confusion about direction of dipole arrow in alpha-helices and other molecules

I understand that molecular dipoles are electric dipoles. And electric dipole moment vectors point from the negative to the positive charge. In class we learned to draw these special molecular dipole ...
0
votes
0answers
18 views

Do we have a reasonable assurance that relative atomic mass is constant throughout the universe? [duplicate]

I know atomic mass can be (over) simplified as the average mass of all isotopes of a given element weighted by the ratio of their natural occurrence. I also know that, as far as we know, refining ...
-2
votes
1answer
43 views

Determining equilibrium concentrations from initial conditions and equilibrium constant

The equilibrium constant for the following reaction is $600^{\circ} \mathrm{C}$ is 4.0. Initially, two moles of CO and one mole of H2O were mixed in a 1.0 liter container. Determine the ...
3
votes
1answer
56 views

Equilibrium concentration, Where does the 5.00 for FeSCN^2+ comes from, and how do you solve this problem?

Trial #1: $$\ce{Fe^3+(aq) + SCN^- (aq) -> FeSCN^2+(aq)}$$ \begin{array}{|r|c|c|c|}\hline \mathrm{Initial~}(M)&\phantom{-}6.00 &\phantom{-}10.00&\phantom{-}0.00\\\hline ...
3
votes
1answer
34 views

Alcohol in the bloodstream modeled by differential equations

Does anyone know any good references which use partial differential equations to model the alcohol concentration in the bloodstream? I'm a mathematician, so I'm searching for a rigorous mathematical ...
2
votes
1answer
40 views

Why is lithium bromide used in absorption refrigerators?

Lithium bromide refrigerator Why is lithium bromide used in absorption refrigerators? It is more expensive than sodium chloride. The wikipedia article on lithium bromide says it is extremely ...
1
vote
0answers
23 views

Molar conductivity and concentration

For strong electrolytes, according to Kohlrausch, molar conductivity decreases as the concentration increases. ( i don't know why I'm not allowed to attach a photo here in order to show you the ...
3
votes
2answers
62 views

How do I setup the electrodes for cyclic voltammetry on a capacitor made on dry copper sheets?

I'm trying to measure capacitance of a cell I'm creating. It's composed of two copper-sheets with nano-material coated on one side, sandwiched with a membrane and wetted with $\ce{KOH}$. All of the ...
0
votes
1answer
28 views

According to this equation for glycolysis, what is reduced and where do the electrons go?

I know that the glucose is oxidized into pyruvate but I don't understand what is reduced or where the electrons go.... Equation: $\ce{Glucose + 2 ADP + 2 NAD^+ -> 2 Pyruvate + 2 ATP + 2 NADH}$
3
votes
1answer
32 views

Regarding Gibbs's function, why is there non-expansion work?

It has been defined as the energy available for work other than expansion work. Why can't it be used for expansion work? I think I'm missing something here
2
votes
0answers
44 views

Oil refinery - How many plates are needed for a 10 degrees difference in temperature?

I am having some trouble going about this question. My first thought is to set up an ASTM separation equation to figure out the difference, but I do not know how to incorporate the reflux ratio ...
0
votes
0answers
22 views

Equivalents Chemistry [duplicate]

Why equivalents of reactants and products come out to be equal in a reaction? I am seeking logic behind the law of chemical equivalence and i have just asked it for clarifying the concept.
0
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0answers
37 views

When the heat is absorbed by the ice then ice will melt to form liquid water

My new try: Given data Energy given by reaction =1690 kJ Initial temperature = 0 oC Final temperature = 50 oC C water = 4.18 Jmol-1 K-1 ?Hfus ice = 6.01 kJ*mol-1 Calculate Mass of ice = ? Ice ...
1
vote
0answers
52 views

Explanation of the law of equivalence

According to the law of equivalence, the number of equivalents of each reactant and product in a reaction are equal. Why is it so ?
4
votes
1answer
31 views

Respect to other chemicals in reduction/oxidation potentials

From what I understand, the standard reduction/oxidation potential table is based on the hydrogen half reaction which makes a reduction and oxidation potential of 0 respectfully. In a research ...
7
votes
1answer
55 views

What are the conditions for liquid metal to be corrosive to another, different solid metal?

I've had already been aware of the fact that metallic aluminum can be degraded by coming in contact with mercury, but also came across another question more recently here explains a similar reaction ...
3
votes
1answer
41 views

Equilibrium constant in terms of partial pressures

$K_p$ is defined as $\Pi_j(\frac{P_j}{P^{\Theta}})^{\nu j}$ where $P_j$ is the partial pressure of component j and $\nu$ is the stoichiometric coefficient. I have a couple of questions already. ...
7
votes
1answer
61 views

How is it possible for a substance to have a high heat of vaporization but a low boiling point?

The final paragraph of Dissenter's question here is worthy of standing alone: [H]ow does one square a high heat of vaporization with a low boiling point? If it takes a lot of energy to vaporize ...
5
votes
2answers
53 views

Super-cooled liquids

I understand that it is possible to cool a liquid past its freezing point, and still maintain its liquid state because crystallisation would not happen in the absence of a seed crystal. My question, ...
0
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0answers
38 views

Faraday's law problem

Electricity has been through electrolizers with saturated solutions of sodium chloride, aluminum sulphate and cobalt chloride (II). In each of the electrolyzers, two of the electrodes were from ...
5
votes
2answers
104 views

Can all substances be supercooled?

With optimal conditions can we supercool any compound or is it that just water and a certain set of others can be supercooled? If not, why?
3
votes
1answer
34 views

Conditions affecting pseudo rate orders

For the reaction: $$\ce{F + Br_2 -> FBr + Br}$$ The gas concentrations as a function of time are given by: $$kt=\ce{\frac{1}{[Br2]_0-[F]_0}}\ce{\ln(\frac{[Br2][F]_0}{[F][Br_2]_0})}$$ Given that ...
6
votes
1answer
32 views

How are piezoelectric crystals made?

I want to know how the powdered formed of piezoelectric material is converted to crystal like used in quartz watches. I know that some more chemicals are mixed with the material and then it is pressed ...
1
vote
0answers
37 views

Entropy change when liquids at two different temperatures are mixed

Two quantities of water ($M_\mathrm{r}=18$) each of mass $216\ \mathrm{g}$ are mixed together in a vessel. The temperatures of the two quantities before mixing are $303\ \mathrm{K}$ and $333\ ...