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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Calculation of Calorimeter Constants [on hold]

$\mathrm{100~g}$ of water at $\mathrm{45~^\circ C}$ is added to $\mathrm{100~g}$ of water in a calorimeter at $\mathrm{20~^\circ C}$. The temperature of the mixture is $\mathrm{30~^\circ C}$. ...
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1answer
16 views

Do Slater's rules apply to neutral lithium (at least approximately)?

For lithium, the electronic configuration is $\ce{(1s)^2(2s)^1}$. I tried to calculate $Z_{eff}$ for the $\ce{2s}$ orbital of the neutral atom as follows: $$Z_{eff} = Z-\sigma$$ $$Z_{eff} = ...
2
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12 views

How are solubilities of hydrate salts determined when competing equilibria are unavoidable?

When you calculate the solubility product constant for a salt and one of its hydrates, you sometimes get drastically different numbers! I don't know how this can be because they both dissociate into ...
1
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1answer
42 views

How could a rechargeable battery recharge itself?

I'm an engineering student preparing for my graduation, in one step of my graduation project I used a rechargeable battery(1.2 volt), i was shocked when this battery is starting to recharge it self ...
6
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1answer
95 views

Analytical solution of the Schrödinger Equation for AB^+ systems

According to Wikipedia, there are not many problems for which the Schrödinger equation can be solved analytically. [1] The $\ce{H2+}$ ion is probably the most complex molecule that can be treated this ...
2
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16 views

Is there a relationship between viscosity and enthalpy of vaporization?

It would be useful to be able to predict relative evaporation rates of liquids. For small reduced temperatures the heat of vaporization is relatively constant, but it is not one of the more common ...
4
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1answer
50 views

Finding rate of reaction from a concentration vs. time graph

A tangent drawn on “conc. of product vs. time” curve of a 1st order reaction makes an angle 30 degrees with the $y$-axis at 20 min. Find the rate after 20 min. I first tried to find the equation ...
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3answers
58 views

Why is SiO2 solid while CO2 is a gas?

I was under the impression that chemistry almost exclusively involves valence electrons because there isn't enough energy to strip off electrons located closer to the nucleus. If that is true, and ...
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16 views

Lithium-ion battery powered devices, bad to keep plugged in? [on hold]

There are many folk stories regarding what should be done with lithium-ion powered devices such as phones and laptops. Should a mainstream brand phone (I say this to suggest a battery of average ...
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25 views

What phase of matter is salt when dissolved in water? [duplicate]

Being an ionic solid, salt is very susceptible to being torn apart by the polar molecules of water. Inside the water, salt exists as sodium and chlorine anions; but what state of matter is it in? My ...
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35 views

How do you explain diffusion in terms of the particulate nature of matter? [closed]

If you add a few drops of red food dye to a beaker of water, the red food dye in the water will spread out and colour the water red. What is going on if you try to explain it in terms of how the ...
1
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1answer
33 views

Dry Hydrogen Production

I am building a set-up to produce a controlled flow of dry hydrogen. I'm aiming for around 99.5 percent purity. Am I right in thinking a PEM cell and Deterite drying tube should be fine for this? Or ...
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22 views

Is There an Acceptable Potential Which Can Represent the Interaction between Finite-sized Ions?

The question is as mentioned in the title. Take for example the interaction between $\ce{Ar^+}$ and $\ce{Ar^+}$. In general, is there an acceptable potential which can represent the interaction ...
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23 views

Why can't hot water break disulfide bonds when the energy storage in hot water exceeds the bond energy?

I teach Biochemistry and know that heating water can break weak bonds like hydrogen bond or ionic interaction, but not disulfide bond (without reducing agent). The bond energy of hydrogen bond in ...
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33 views

Period of Vibrational Modes

I am trying to understand more about the period of vibrational nodes. Currently, I am interested in Si-O bond stretching in silica. I think this value is about 1000 cm^-1 I am somewhat confuse on how ...
4
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1answer
95 views

How does molecular collision excites the electron?

I have this question for a long time that in LASER when we do the pumping by heating how does molecular collision causes the atoms(molecules) to reach in excited state. E.g. in $\ce{He-Ne}$ laser when ...
2
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1answer
47 views

What Methods Would I Use To Powder Cotton?

I’m needing a method to turn cotton into a fine powder for use as a source of cellulose. What suggestions would you give to accomplish this with materials/tools that could be obtained at local stores? ...
3
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1answer
185 views

Yellow Color of NaCl

My book says - "NaCl shows metal excess defect, which results into the formation of an F-center in the crystal. This F-center is responsible for the yellow color of NaCl." My question is, how does an ...
2
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0answers
26 views

Difference of aggregate and cluster?

Can anyone tell me the difference of aggregates and clusters from the molecular point of view? Thank you so much.
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34 views

How do you determine stable oxidation from Ionization energy

Question: You have been given the first, second and third ionization energies of an element as 7eV, 12.5eV and 42.5eV, respectively. How do you find the most stable oxidation state (or charge on the ...
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20 views

Thermodynamic-Fuel and efficiency

Why is the maximum theoretical efficiency of Ar engine higher than that of Nitrogen engine? On a molecular level. For an Otto Cycle $\mathrm{Eff} \le\left(1-r^{1-\gamma}\right)$ ...
2
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0answers
32 views

Neutralization reaction with insoluble salt (weak acid, strong base)? [duplicate]

Consider the following reaction. $\ce{2 HF(aq) + Ca(OH)2(aq) -> CaF2(s) + 2 H2O(l)}$ The reaction produced a fairly insoluble salt. Assume that this reaction proceeds entirely to completion as ...
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0answers
18 views

Mole fraction of the solvent related to vapor pressure [closed]

The vapour pressure of a solvent decreased by 10 mmHg when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be the mole fraction of ...
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1answer
31 views

Using vapor mole fraction and pressure to determine liquid mole fraction

I am studying Chemistry by Zumdahl and Zumdahl (9th edition) and I have come across a question in Chapter 11 that I can't figure out the explanation for: Liquid A has vapor pressure x , and liquid B ...
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2answers
62 views

How can I convert the number of particles per liter to gram per liter

How can I convert the number of particles per liter to gram per liter? I know the size of these particle and so, I calculated the volume and then by the density I calculate the mass. After that I ...
4
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1answer
38 views

Difference between ideal & ideal-dilute solution

These two terms has been frequently used in Physical Chemistry by Atkins. He describes Raoult's Law using ideal solution while Henry's law using ideal-dilute solution. I thought, at first they were ...
3
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1answer
47 views

Heat capacity of mixtures

After reading this recent question I was interested in how to calculate the specific heat capacity of a mixture based on the specific heat capacities of its components. According to this website the ...
3
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1answer
55 views

Finding large databases of sphere packings

Part of my research is investigating sphere packings and their properties.I really would like a large database of sphere packings that I could investigate using a program I have written that tells me ...
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1answer
37 views

Why does the first lithium stationary state have n = 9/4

The question is :- The ionization energy of $\ce{He+}$ is $19.6 \times 10^{-18}~\mathrm{J~atom^{-1}}$. What is the energy of the first stationary state ($n=1$) of $\ce{Li^{2+}}$? Since the question ...
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1answer
41 views

How come the value of principal quantum number is an irrational number?

My textbook says that for a d-electron, the orbital angular momentum is $$ \frac{\sqrt{6}h}{2\pi} $$ But since:- $$ mvr = \frac{nh}{2\pi}$$ $$ n \in N$$ where N is the set of natural numbers. So how ...
3
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1answer
32 views

Is it possible to calculate specific heat capacity of a compound based on its elements' heat capacities?

What the question says. For example, if I knew the specific heat capacities of lithium and oxygen, could I work out the specific heat capacity of lithium oxide with no further information?
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22 views

meaning of hydrodynamic dimension

Can anyone tell me what the meaning of hydrodynamic dimension is and the relations between hydrodynamic dimension and hydrodynamic radius? Thank you so much.
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1answer
51 views

Does caesium or francium have a lower ionization energy?

$\ce{Cs}$ and $\ce{Fr}$ are in the same group of lowest first ionization energy, but which element has the lowest ionization energy, and why?
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13 views

electronic configuration of lanthinide series [duplicate]

Why does the 57th electron enter the $5d$ subshell in lanthanum, shouldn't it should enter the $4f$ subshell according to the Aufbau rule? Also in thorium, the 89th and 90th electrons enter ...
0
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1answer
36 views

Why does cationic charge density affect metallic bonding?

Group II metals have a smaller cationic size but one more valence electron than Group I metals. Why would the higher charge density of a metal cation affect the strength of the bonding of it in its ...
5
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1answer
120 views

Can molten sugar also rotate polarized light as sugar water does?

It is well know that the sugar water can rotate the plane of linearly polarized light, so light bends when travelling in sugar water. However, do the liquid state of sugar but not the sugar solution ...
4
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1answer
37 views

Is there a relationship between London dispersion forces and hydrophobic interactions? [duplicate]

Looking at examples of these two molecular interactions makes me wonder what the differences or similarities are exactly.
3
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1answer
294 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 ...
2
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2answers
94 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 ...
5
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39 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
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1answer
63 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 $\ce{B}$ ...
2
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1answer
50 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
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1answer
41 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
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1answer
32 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
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1answer
94 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 ...
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1answer
48 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
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1answer
26 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 ...
2
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2answers
69 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
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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
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1answer
77 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? ...