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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16 views

How to explain Born repulsion between ions in gas phase?

In simple terms, the collision of two atoms $\ce{A}$ and $\ce{B}$ will result in ions $\ce{A^+}$ and $\ce{B^-}$ if $$I_a(\ce{A})+E_a(\ce{A})<I_a(\ce{B})+E_a(\ce{B})$$ where $I_a$ and $E_a$ are the ...
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24 views

Spectator mode; what is

I'm reading a paper, found a line: "The other modes have relatively small contributions for the displacements of the heavy atoms and can be considered as spectator modes for the internal conversion". ...
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20 views

what is the amout of pressure that is needed to make alcohol evaporate/boil at room temperaturecelsius or around 20-25°C

I need to make alcohol evaporate from a solution without bringing it to a high temperature. I do know that is achieved by putting the solution under pressure but what i don't know, and cant find ...
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2answers
79 views

Is glass an amorphous solid or supercooled liquid?

I have been informed that glass is a super-cooled liquid and is also considered to be an amorphous solid. Can it be both and, if not, what category does it fall into?
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0answers
14 views

Vapour pressure of water and ether [on hold]

At room temperature vapour pressure of water and ether are: a) different b) same c) zero d) none of these
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28 views

What are the consequences of Planck's constant being different from the current value ? [on hold]

Does it have drastic effects in the nature of the physical world ?
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13 views

how to calculate the new value of equilibrium constant after doubling the volume of vessel [on hold]

The equilibrium concentrations of A and B for the reaction A(g) + 2 B(g)=== C(g) are 3M and 4M respectively.when the volume of vessel is doubled and the equilibrium is allowed to re establish the ...
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33 views

What is de-Broglie's hypothesis?

Was the relation between wavelength and momentum derived or is it just an empirical relation ?
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1answer
19 views

What makes DNA/Protein in a gel run in straight lines?

In a gel electrophoresis, let's assume an SDS-PAGE, I understand that the sample is loaded on a cuboidal well and the electric field is straight downward. It is easy to assume that the sample is going ...
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14 views

Help needed with this numerical [on hold]

If 2.3 mol of a gas occupies 50.5 ml how many moles of the gas will occupy 85.5 mL at the same temperature and pressure?
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11 views

Why are these materials like gallium arsenide, gallium phosphide, aluminium gallium arsenide etc used in Light Emitting diodes?

Indium gallium nitride (InGaN): blue, green and ultraviolet high-brightness LEDs Aluminum gallium indium phosphide (AlGaInP): yellow, orange and red high-brightness LEDs Aluminum gallium arsenide (...
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18 views

Why don't we see coupling for chemically equivalent protons? [duplicate]

I know that the peaks of chemically equivalent protons do not split with respect to each other in proton NMR. For example, we do not see coupling between the protons in ethane: the spectrum consists ...
2
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48 views

Quadrupole moment of a molecule [closed]

What is a quadrupole moment of a molecule and how does it arise? How is it measured for a particular molecule?
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38 views

What causes mercury to expand equaly unregarded what the temperature increase is?

Mercury seemed to be a good liquid to use in thermometers. But why are most liquids expanding non-linearly with increase of temperature compared to other liquids?
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0answers
14 views

phase differences between conical intersections and light-induced conical intersections?

I've read recently about light-induced conical intersections, a phenomenon where conical intersections can be artificially introduced to molecules, and that this can be observed even in diatomic ...
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0answers
15 views

Hi, I need to plot S = k log W against T in Kelvin from T=0 to T=100 [closed]

I need to plot S = k log W against T in Kelvin from T=0 to T=100 for CO HCl Can anyone help me understand the relation between W and CO/HCl?
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2answers
33 views

Is there a way to counteract the problems with weighing hot objects?

I am currently performing an experiment in which it would be greatly beneficial to be able to accurately measure the mass of a hot object without waiting for it to cool. The current plan is simply to ...
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0answers
20 views

Understanding Energy Diagram for Molecular Rotation - help! [closed]

The question below is from MOOC course Molecular Structures and Quantum Mechanics. From these 2 equations :PROLATE hBJ(J+1) + h(A-B)(K^2) OBLATE hBJ(J+1) + h(C-B)(K^2) we are required to find the ...
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0answers
19 views

Combine Fluoride with gum base

I am trying to figure out whether it's possible to bond fluoride NaF or SnF2 to the gum base of chewing gum. Gum base is typically includes the following: elastomers: styrene-butadiene rubber, butyl ...
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0answers
16 views

Will an Etg alcohol test detect 24oz beer in 82 hours?

I drank a 24oz coors light beer on Sunday and went to sleep at midnight. I had a irons test done on Thursday morning. Will It show up?
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3answers
162 views

Why exactly does molten NaCl explode, when it is poured into water?

Why does molten $\ce{NaCl}$ explode, when it is poured into water? $\ce{NaCl}$ has a high melting point, $1074\ \mathrm{K}$ ($801~\mathrm{^\circ C}$). $\ce{NaCl}$ has a molar mass of $58.44\ \mathrm{...
0
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1answer
21 views

Ignoring the difference of concentrations of reactants. Equilibrium

Recently at school, while studying equilibrium we learned that in problems where the initial concentrations of reactants and the equilibrium constant are given, there is a special formula to determine ...
3
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3answers
67 views

Reactant energy distribution and spontaneity of reactions

I wonder about the implications of substances having an energy distribution around a mean, as opposed to them all having the same energy level, on the spontaneity of reactions. 2 somewhat separate ...
4
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1answer
89 views

Tunneling corrections in reaction rates

I've studied Transition State Theory since I asked this a while ago, but so far I have not been able to find a detailed explanation of how tunneling corrections are implemented into reaction rates ...
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0answers
56 views

What's up with this quarter / three-quarter rule?

A 'quarter / three-quarter rule' is mentioned when discussing the stability of f-orbitals. What the clock does this mean? I haven't ever encountered it before, and the explanation at the above link ...
4
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1answer
94 views

What is meant by 'electrons of like/unlike rotation'?

Explaining the reasons behind electron repulsion, Radiochemistry asserts that, Interelectronic repulsion in related not just to electron pairing, but also to [the] angular momentum of the ...
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40 views

Howcome orbitals become 'core-like' when electrons are removed?

It seems to me that f-orbitals for lanthanide metals are treated as 'core-like' when a certain number of electrons have been removed. Or, as Radiochemistry puts it, The 4f binding energy is so ...
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1answer
81 views

Why don't we see these lanthanide species?

For most lanthanide metals$^{[1]}$, the stable oxidation state is III. The general electronic structure$^{[2]}$ is $$\ce{[Xe] 4f^{0}^{-14} 5s^2 5p^6 5d^{0}^{-1} 6s^2}.$$ Elements that have the d-...
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1answer
29 views

Nernst equation: half cell vs overall reaction

Can the Nernst equation always be applied to the overall redox reaction as opposed to only half cell reactions? For example, in the following silver-silver chloride electrode: $$\ce{Ag (s)|AgCl (s)|...
2
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68 views

Predominance of III oxidation state for lanthanides [closed]

For most lanthanide metals, the stable oxidation state is III [*]. The general electronic structure is $$\ce{[Xe] 4f^{0}^{-14} 5s^2 5p^6 5d^{0}^{-1} 6s^2}\ \ [**].$$ Elements that have the d-electron ...
0
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1answer
41 views

For what is reaction enthalpy more relevant than reaction free energy?

I know enthalpy is a component of the Gibb's Free Energy (along with entropy). For practical purposes, though, isn't Gibb's Free Energy what a chemist is actually interested in, as that determines the ...
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1answer
23 views

Order of ionization enthalpy

The order of successive ionization enthalpies of group 15 are as follows : $$\Delta H_1<\Delta H_2<\Delta H_3$$ But as all the fifteen group elements have a very stable electronic ...
3
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1answer
232 views

How are van der Waals parameters determined experimentally?

If the ideal gas law $PV=nRT$ is not enough, as a second approximation the van der Waals equation $$\left(P+a\frac{n^2}{V}\right)\left(V-nb\right)=nRT$$ is applied. The constants $a$ and $b$ are van ...
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2answers
57 views

why can't salt water and fresh water mix.

why can't fresh water and salt water mix. What happens when they collide with each other? What are their differences?
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2answers
21 views

How to determine if a given reaction requires heating to initiate?

At room temperature, some reaction propagate merely upon intermixing the reagents (e.g. autoignition of triethylborane), while others require additional heat to initiate (e.g. crystallization of ...
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14 views

Is it useful to calculate enthalpy of formation of complex compounds?

The typical textbook treatment of enthalpy of formation involves "elementary" compounds and bonds. How accurate would it be to use those tabulated values to calculate enthalpy of formation of complex ...
7
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2answers
93 views

Why don't equivalent hydrogens cause splitting in NMR?

When doing NMR spectroscopy, it is an observed fact that equivalent hydrogens do not split one another. Why don't equivalent hydrogens split each other's signals? For example, why is the NMR spectrum ...
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0answers
27 views

Doubt regarding Degree of association

I just wanted to ask, Whenever we calculate the degree of dissociation or degree of association, Is it important to start with 1 mole? Because i drived the same equation given below by using "n"...
-1
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1answer
43 views

Partial pressure of gases in liquid [closed]

I was trying to understand what partial pressure of a gas in a liquid means and found the following sentence in a book I don't get it fully. What does it mean, can someone please explain? (What does ...
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0answers
16 views

Covalent bond and ions? [duplicate]

Are atoms in a covalent bond ions? For example water, does oxygen become the 0 2- anion or is this not correct to say since a covalent bond refers to the sharing on electrons? Im assuming atoms are ...
4
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2answers
154 views

Why is EDTA most soluble at a pH 8? (addition of NaOH)

Although Wikipedia says that EDTA is a very soluble salt, preparing a solution (.5M) is a pain in the neck. It takes a lot of time and still doesn't dissolve. Although addition of a few drops of NaOH ...
6
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0answers
53 views

Compound with a bright green emission when electrically excited

I rolled back the edit because I really am looking for the following: I am looking for an element or compound that would have a bright green emission when electrically excited and is a gas at between ...
0
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0answers
25 views

Triple Point Equation

Is there any equation that can calculate the triple point of a substance? Because a method for calculating the critical temperature and the Boyle temperature of a substance that I posted in another ...
1
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1answer
46 views

why is laser printer toner magnetic?

I had an old toner cartridge lying around, so I took it apart and emptied the toner into a jar. I had heard that one could make a ferromagnetic fluid using toner powder and oil, so I mixed a little ...
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0answers
17 views

Vapor pressure, volume and boling point

The saturated vapor pressure is designated as the gas pressure in a closed container when the evaporation process has reached an equilibrium (when there are as many molecules returning to the liquid ...
1
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0answers
19 views

Why is the specific heat of ethanol not representing experiments

I am in my last year of high school completing an assignment hot and cold packs, and particular the enthalpy behind them. My major lack of understanding is why my calculations are working for heat of ...
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0answers
23 views

Why does changing the dilution of an aqueous equilibrium shift the equilibrium?

Say we have the equilibrium $$\ce{A_{(aq)} + 2B_{(aq)} <=> C_{(aq)} + D_{(aq)}}$$ meaning the formula for the equilibrium constant is $$\ce{K_{c} = \frac{[C][D]}{[A][B]^2}}$$ My understanding is ...
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29 views

Does nucleus moved with electron clouds make the chemical bonds cleavage or electron clouds moved with nucleus?

I know the chemicals bond is the overlapping of electron clouds. There is no real bond in molecules. But the electron clouds surround nucleus. Which one "move" first and lead the other to make two ...
7
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1answer
180 views

Stability of ferrous ions and iron(II) hydroxide in acidic conditions

I was reading a chemisty textbook when I came across the following statement. $\ce{Fe(OH)2}$ is not stable, even more so in basic conditions. [---] $\ce{Fe^2+}$ ions are also less likely to ...
0
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1answer
38 views

How does diluting an acid change pH?

By the Henderson Hasselbach equation, log (salt)/(acid) term is a ratio of the concentrations. So, how can dilution change the pH of the acid as the concentrations of both salt and acid would change ...