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

learn more… | top users | synonyms

1
vote
2answers
37 views

Bombarding atoms with electron gun?

Just to explain this question in a better way just think about the Rutherford's experiment(the alpha particle bombarded on Gold foil) be conducted using a electron gun in place of the Alpha one.. So ...
1
vote
1answer
23 views

Other than heating, is there any evidence that normal RF radiation (say, microwave range) can affect chemical reactions?

There's been a lot written (and debunked) about alleged biological effects from RF radiation, even when it's too low powered to cause heating effects or ionization. Is there any chemical reason to ...
3
votes
1answer
30 views

how are the frequencies at a local maximum of PES like?

On the potential energy surface, if you find a local maximum and calculate its frequencies in Gaussian or something like that, will you get all negative frequencies or all positive frequencies? I know ...
2
votes
1answer
42 views

Wavelength of X-rays

What will be the wavelength of X-ray if we apply a potential difference of , say 20 KV across the ends of the x-ray tube ? Alright, i started with the modified de-broglie equation ...
0
votes
1answer
20 views

How to dissolve grass/leaves without affecting enclosure?

I've got two questions: What sort of compound can dissolve grass/leaves fastest without leaving "much" trace? What sort of enclosure is required for this to be doen safely and without damaging the ...
0
votes
0answers
25 views

Magnesium Sulphate and Calcium Nitrate reaction requires heat

In an effort to create Calcium Sulfate I mixed Magnesium Sulfate and Calcium Nitrate but no precipitate was formed and so I started to boil down the mixture to concentrate the reactants where upon a ...
4
votes
3answers
55 views

Why is the enthalpy of vaporization greater than the enthalpy of fusion?

Why is the molar enthalpy of vaporization of a substance larger than its molar enthalpy of fusion (at constant pressure); for example, in the case of ice and water.
3
votes
1answer
50 views

Intermolecular Hydrogen Bonding

I learnt about intermolecular hydrogen bonding today, which occurs between molecules such as ortho-nitro-phenol. What I was told is that in case of intermolecular bonding, the molecules separate from ...
1
vote
1answer
38 views

What is the mass of 1 Liter of ethylene at 2000 bar pressure?

I was wondering the weight of 1 liter of ethylene at 2000 bar and 310 Kelvin? I have tried to just multiply the weight at 1 bar with 2000 but I don't think i got the correct answer because the answer ...
4
votes
1answer
231 views

What is Sodium Chloride like in gas state?

Since sodium chloride is sodium and chlorine atoms bonded as a lattice and there are no discrete molecules, doesn't that mean in gas state, sodium chloride is simply sodium and chlorine atoms separate ...
1
vote
1answer
44 views

What is the simplest structural unit of an element or compound?

From "Smarter than a 5th Grader": What is the simplest structural unit of an element or compound? molecule, atom, neutron, proton For covalent compounds, the answer would ...
3
votes
4answers
83 views

What is reactivity really, and can it be quantified?

I understand the concept of a reactive species on a sort of vague and intuitive level: a reactive species is one that has lots of reactions that it can participate in. These tend to have large kinetic ...
0
votes
1answer
28 views

How can we say that one mole of a substance contains avogadro number of particles?

I just want to know, what was the procedure through which the value of one mole of a substance was considered as a an aggregate of $6.023\cdot10^{23}$ particles. Secondly, how do we calculate the ...
0
votes
2answers
14 views

Chemical reactions in SFE?

What are the chemical reactions and/or chemical processes that take place during SFE(supercritical fluid extraction)? Namely supercritical $\ce{CO2}$.
1
vote
2answers
38 views

Reconciling the units of pH calculation

As part of a simulation I am developing I have an acid in aqueous solution represented as a concentration field of mass density (units g/L) at various points in ...
2
votes
2answers
39 views

Plot of Arrhenius Equation with temperature

I saw the plot of Arrhenius Equation Here It is a concave upwards graph, but acc to the equation $k= A e^\frac{-E_a}{RT},$ it is evident that the graph is of the form $y= e^\frac{-1}{x}.$ I ...
3
votes
1answer
115 views

Kinetics of Interstellar Chemistry — Applying steady state to formation of H₂

I am trying to solve problem 2 from the 2009 International Chemistry Olympiad (IChO), which is as follows: If two atoms collide in interstellar space the energy of the resulting molecule is so ...
4
votes
1answer
48 views

Why are solids and liquids not included in the equilibrium constant? What about in a reaction rate calculation?

Take for instance the rection $$\ce{H2(g) + I2(s) -> 2HI(g)}$$ The equilibrium constant would not include the solid $\ce{I2}$, but why is this? I have read that its concentration is a constant, ...
0
votes
1answer
34 views

Solar still and how it works

I use a solar still that holds 182 cubic feet of water. Here is how it works: There is an insulator on both sides of the metal bowl. On the outside it covers the whole thing. on the inside it covers ...
1
vote
1answer
40 views

Units for dissociation constant and relationship to Gibbs Free Energy

How does one "convert" between an equilibrium constant calculated from the Gibbs free energy for a dissociation reaction and experimentally determined dissociation constants? $$ \Delta ...
0
votes
1answer
45 views

Why does the lone pair of phosphine not contribute to its dipole moment?

Unlike ammonia,the lone pair of phosphorous does not add to the dipole moment of phosphine. My textbook says this is due to the presence of lone pair of phosphorous in $PH_3$ in $s$ orbital. I ...
4
votes
2answers
83 views

How does lone pair of a central atom affect the dipole moment?

Dipole moment is the degree of polarity ie. seperation of positive and negative charges. But I am not getting the intuition why and how lone pair affects the polarity and dipole moment.I cannot ...
1
vote
1answer
18 views

How can we calculate enthalpy change in a closed tank containing methanol adsorbed by activated carbon?

Here's the problem in the simplest way: I have a closed box containing methanol adsorbed by activated carbon. The box is made from copper. A pipe is connected to that box, which has condenser on the ...
0
votes
0answers
12 views

Simulating enzymatic change rates of Carbonic anhydrase

I'm trying to simulate effects of carbonic anhydrase on cellular pH as caused by changes in bicarbonate. I assume a bicarbonate homeostatic mechanisms which replenishes intracellular conenctrations ...
0
votes
1answer
30 views

Can a clay brick waste in a soil be a source of minerals for plants?

Clay brick is made by heating them so their clay structure changes. What i understand is ultimately all materials have one or another base minerals in it particularly here this brick still it remains ...
0
votes
2answers
54 views

Does the distance increase as the polarity increases?

According to the dipole moment's definition, as polarity increases the distance between the centres of positive charge & negative charge increases.In the ionic bond ,as the polarity is maximum, ...
0
votes
1answer
28 views

Is there a possible effect of low frequency mechanical vibration on the stability of organic molecules

Is there a possible theoretical effect of mechanical vibration on the stability of organic molecules. E.g. some medicines degrade if they are not stored in a fridge, is there a theoretical ...
1
vote
2answers
38 views

Finding the initial concentration

The solubility product of $\ce{AgBr}$ is $7.7 \cdot 10^{-13}\:\mathrm{mol^2/L^2}$. What was the initial concentration of $\ce{AgNO3}$ solution, if the precipitation of $\ce{AgBr}$ appears after the ...
0
votes
0answers
37 views

production rate from chemical reaction [closed]

I have the following reactions (1)$\ce{NaOH+CO2+M=NaHCO3+M}$, K1 (2)$\ce{NaHCO3+H=Na+H2CO3}$, K2 (3)$\ce{2NaHCO3+M=(NaHCO3)2+M}$, K3 ki's are the rate constants. Suppose $\ce{NaHCO3}$ is a ...
0
votes
2answers
49 views

Calculate the molality and molarity of this simple solution [on hold]

Concentrated hydrochloric acid contains 37% (by mass) $\ce{HCl}$. The density of its solution is $\mathrm{1.18 g/ml}$. Calculate the molarity and molality of the solution.
0
votes
0answers
18 views

What is relationship between molecular weight distribution of PE and its strength?

I'm trying to figure out the relationship between the molecular weight distribution of a polyethylene plastic and its strength and heat sealability. (The molecular weight distribution is described ...
0
votes
1answer
42 views

What is defined by part by weight in the definition of equivalent weight?

Acc. to my book,equivalent weight is defined as the 'number of parts by weight' of an element that interacts with $1.008$ parts by weight of hydrogen.It is dimensionless while gram equivalent weight ...
3
votes
1answer
58 views

Finding overall order of reaction

Recently I've been going through an exercise of Chemical Kinetics and Nuclear Chemistry and right now I am stuck to one. Question was previously asked in JEE(Advanced)-2013. The question says, In ...
1
vote
1answer
55 views

Why does the solubility of Group II hydroxides increase and the solubility of sulphates decrease down the group?

I know that, solubility of alkaline earth metal hydroxides increases down the group and solubility of alkaline earth metal sulfates decreases down the group. Would you please explain me the reason ...
3
votes
2answers
65 views

Explanation for the reactions in a saltwater battery with zinc and copper electrodes

I am a physicist, not a chemist. I'm trying to get a basic understanding of the reactions taking place in a battery using a saltwater electrolyte with copper and zinc terminals. I'm writing a general ...
1
vote
0answers
9 views

Atmospheric Humidity Effects on Non-water Evaporation

Does evaporation of non-water liquids into the atmosphere vary with atmospheric humidity?
0
votes
1answer
18 views

Empirical and Molecular Formulae

I'm not a chemist, and nor do I study chemistry so please try to be gentle. Glucose has the molecular formula $\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6$ and the empirical formula ...
0
votes
3answers
45 views

Reduce sizing of molecule - Oxygen

Can the size of molecule oxygen reduce smaller? If yes, how is that possible? Is it related to proton and electron surrounding the nucleus?
2
votes
0answers
35 views

Specific Heat of Water Solution

If we add an ionic solute to water, will the specific heat of the water be increased or decreased? I understand that the specific heat is a measure of how much energy we must add to water for the ...
0
votes
3answers
19 views

Hess Cycle, determining enthalpy change of formation

I am asked to find the enthalpy change of formation of the following: $$\ce{N2 + 1/2O2 -> N2O}$$ I am given the following enthalpies of reaction: $$1:\:\ce{C + N2O -> CO + N2} \:\:\:\Delta H_f ...
0
votes
1answer
33 views

Finding out the number of atoms in the sun.

This is the question from the text book: This is what I did, since it worked with all the previous questions (similar to this). $$ \frac{\frac{4}{3}\pi(7*10^8)^3*1.4}{1.008} * 6.022*10^{23} $$ ...
2
votes
1answer
27 views

Number of collisions of particles in a box (or a sphere)

Imagine you randomly spread in a cubic space of volume $m^3$ (or in a sphere of volume $V_s$, as you prefer), $n_A$ particles $A$ and $n_B$ particles $B$. Particles $A$ are spheres of volume $V_A$ and ...
0
votes
0answers
18 views

Graph theory, isomer enumeration and chemical graph theory

Where could we find a good description of graph theory applied to the general problem of isomer enumeration and chemical graph theory?
1
vote
0answers
28 views

Making a reasonable slab of alpha quartz

I want to perform a molecular dynamics simulation with alpha-quartz as my mineral surface. I want to study adsorption of water on alpha-quartz. The most dominant error that I came up with is the ...
9
votes
3answers
3k views

Why doesn't a table sublimate, while ice does?

A table does not sublimate, and nor does a spoon. Ice does, however. What is the fundamental difference?
0
votes
1answer
58 views

How to calculate the number of moles present in a litre of saturated solution?

The solubility product of a salt having same molecular formula as $\ce{Ca_3(PO_4)_2}$ is $1.08\cdot10^{-28}$. Then find the number of moles of ions present in the saturated solution. My approach: I ...
8
votes
2answers
120 views

Relationship between magnitudes of forward and reverse kinetic rate constants

Consider the reversible unimolecular reaction: $A \overset{k_{1}}{\underset{k_{2}}{\rightleftharpoons}} B$ We know that the forward reaction is often considerably more thermodynamically favourable ...
3
votes
1answer
40 views

What attributes cause a substance to be nonconductive or conductive

I understand what causes elements to be conductive or nonconductive. But what causes a substance say rubber to be nonconductive at a molecular level?
2
votes
2answers
59 views

Semi-Infinite Potential Square Well: Negative Potential

I am having trouble with a problem involving a Semi-infinite potential square well: I have written down some notes that I added to the post. I have problems understanding the physical situation. See ...
0
votes
1answer
41 views

pH of a solution of acetic acid and ammonium acetate

After studying ionic equilibrium, I was just making some wild questions and I was unable to calculate the $\ce{pH}$ of this solution. Assume, 1 mole of each was added to $1L$ solution of water. My ...