Study of macroscopic and microscopic phenomena in chemical systems in terms of physical laws and concepts [thermodynamics, statistical mechanics, kinetic theory, quantum mechanics...].
1
vote
0answers
57 views
Chemical Equilibrium - Why does changing the temperature shift the equilibrium? [migrated]
I know that raising the temperature in a reversible chemical reaction causes the equilibrium to shift to the endothermic side.
I know that $\Delta G = \Delta H - T \Delta S$ but I don't know how to ...
2
votes
2answers
69 views
How to estimate the physical size of a molecule?
I'm reading some chemistry-related papers that employ concepts of droplet evaporation. Since I am no chemist, I am wondering:
How can I estimate the actual size of a molecule, say succinic acid?
An ...
1
vote
2answers
41 views
Vaporizing ethanol from liquid
What is going on here http://youtu.be/LQFmKPA-iAg
Is ethanol leaving the liquid? If so, why?
Does the pressure add energy to the ethanol molecules causing them to gasify and move rapidly near border ...
-3
votes
0answers
20 views
Vapor Deposition Chamber : Ship of Theseus [closed]
I would like to know if anybody here might be in the position to allow me to send you my pen's push cap (CARAN d'ACHE), and then have some aluminum vapor-deposited on to it. I tried making a vapor ...
-3
votes
0answers
52 views
If air contains oxygen and nitrogen, why won't these two elements form water? [closed]
If air contains oxygen and nitrogen, why won't these two elements form water?
Shouldn't these two elements react and form water? Why do they stay seperated?
1
vote
0answers
20 views
Solution of multiple materials
Introduction
I'm trying to make some strawberry liqueur. The recipe I got says I should put alcohol, strawberries and sugar in a bowl and leave it soaking for 4-5 weeks. I read that making liqueur is ...
-2
votes
2answers
97 views
what is the density of natural gas at 293K and 700 kPa? [closed]
I am trying to calculate the density of natural gas to define the amount of natural gas flow through an orifice. I am coming up with 5.45 kg/m3 Is this correct?
0
votes
2answers
39 views
A question on lewis model [closed]
Electron affinity of chlorine = -349 kJ per mole. And, first ionization energy of sodium = 496 kJ per mole while energy required for combining= 147 kJ per mole.
Isn't it a contradiction against ...
0
votes
1answer
63 views
What is tricritical point？
Critical point is the transition temperature of a second order phase transition. But what does tricritical point mean? WIki says that a tricritical point is a point in the phase diagram of a system at ...
0
votes
1answer
77 views
How fair is it to say that all chemistry arises from failures of the ideal gas law?
I was reading here about how the ideal gas law assumes point masses and non-interaction. Is it fair to say that all chemistry arises from failures of that?
Of course, such a sweeping generalization ...
6
votes
1answer
107 views
How much Bicarbonate of Soda and Vinegar would I need to reach space?
So here is my problem - as part of my job I present some science demonstrations to children and one of the tricks I regularly use is the bicarb/acetic acid rocket. I thought the other day that a ...
-4
votes
1answer
88 views
How fast will I get if I burn a comet? [closed]
Assuming I have a spacecraft which is $30,000\,\mathrm{kg}$ (roughly the size of the Apollo spacecraft).
If I take a comet and (theoretically) electrolize it perfectly to hydrogen and oxygen. I know ...
5
votes
2answers
110 views
Solidification by the application of heat
When you add heat to a liquid (or a fluid), can it be solidified? If not, why in the world does an egg's stuffs become solid (or at least no more a liquid) when you 'boil' it in water?
0
votes
2answers
54 views
What is “species” in the context of an electrochemical cell?
From the Wikipedia entry on Electrochemical cell (http://en.wikipedia.org/wiki/Electrochemical_cell):
An electrochemical cell consists of two half-cells. Each half-cell
consists of an electrode, ...
0
votes
1answer
97 views
Difference between Non-Polar and Dipole moment $\vec\mu$=0
Is there any difference between a molecule having $\vec\mu=0$ and being Non-Polar?
2
votes
1answer
51 views
Reason behind cohesive and adhesive force
What is the real cause behind the cohesive and adhesive forces?
0
votes
2answers
84 views
Carbon in the form of graphite a conductor?
Well, it happens a I have a glucose test strip (One Touch Ultra) which has three electrodes (Counter, Working and Reference) and I'm guessing this electrodes are made from graphite mixed with a ...
1
vote
0answers
63 views
What's the underlying particle physics of endothermic reactions?
I don't just mean reactions that require heat to proceed, storing surplus energy in chemical bonds. I wonder about strongly endothermic reactions that suck heat out of environment.
You take some ...
0
votes
1answer
122 views
Chemical Equilibrium - Why do changes in pressure cause a shift in the ratio of products and reactants?
I understand Le Chatelier's principle and how every change to an equilibrium system causes an opposing reaction from the system. I also understand how, when pressure is increased, the equilibrium ...
0
votes
1answer
92 views
What's the vapor pressure and evaporation enthalpy of a saline solution?
Suppose you dissolve an amount of salt in water. Because of the attraction between the ions and the water molecules, you'd expect lower vapor pressure and higher enthalpie, both depending on the ...
6
votes
2answers
2k views
Why does a salt solution conduct electrical current?
How does e.g. sodium chloride (aq) conduct electricity? By accepting electrons (unlikely since they already have a full outer shell)? But they can't be hopping around themselves, can they? I mean, if ...
4
votes
3answers
145 views
Do electrons in multi-electron atoms really have definite angular momenta?
Since the mutual repulsion term between electrons orbiting the same nucleus does not commute with either electron's angular momentum operator (but only with their sum), I'd assume that the electrons ...
1
vote
3answers
140 views
Can endergonic reactions occur outside of living organisms?
If the Gibbs free energy equation is defined as:
∆G = ∆H - T∆S
And the amount of energy/work released from a reaction is:
...
2
votes
3answers
824 views
is it possible to flow current in open circuit?
First , i don't know much about chemistry and physics. I'm just a graphic designer but i have this question in my mind. I'm sorry if this question is too basic and use 'generic' language.
As i know ...
1
vote
0answers
28 views
Half-Life Question [duplicate]
Possible Duplicate:
How do we know that some radioactive materials have a half life of millions or even billions of years?
I understand how to calculate decay, but it seems to me that the ...
1
vote
0answers
336 views
Is there any reproducible tested evidence for Ni-H cold fusion?
The main replications of cold fusion, the ones that are beyond reproach, used Pd/d as the system. But commercial developers have often claim to use Ni-H to achieve similar effects. The claims include ...
1
vote
0answers
65 views
Are metal modes mixed with molecular modes during surface enhanced Raman effect?
This question is dedicated to Martin Fleischmann (1927-2012).
When a molecule is adsorbed on a metal surface, the Raman scattering amplitude from the molecule is enhanced. According to Wikipedia, the ...
1
vote
2answers
160 views
Where does Computer Science background students fit in Theoretical Physics [closed]
I am basically an Electronics student - background in computer science (that's where I want to work). I applied for an internship in USA in a research institute where the group is focused in ...
3
votes
2answers
1k views
Widom-Larsen Theory
Does the Widom-Larsen theory pose a credible underpinning for Low Energy Nuclear Reactions, often incorrectly referred to as "Cold Fusion"?
http://arxiv.org/abs/cond-mat/0505026
1
vote
0answers
40 views
Why the dangling bonds at the edge terminated by hydrogen atoms give no contribution to the electronic states near the Fermi level
How about changing H atom to other kinds of atoms?
0
votes
2answers
259 views
How does one calculate the volume of a nucleus and the volume of an atom (in this case hydrogen)?
The hydrogen atom contains 1 proton and 1 electron. The radius of the proton is approximately 1.0 fm (femtometers), and the radius of the hydrogen atom is approximately 53 pm (picometers).
0
votes
0answers
18 views
What exponential time dependiciens depends also on temperature?
Are there any laws in nature, which shows exponential decay (or growth) and which also depends on temperature?
For example, don't any chemical transformations demonstrate exponential law? I think ...
0
votes
1answer
49 views
Action on Lard Oil
If water is mixed with lard oil and heated (creating some super-critical liquid with water), how does this affect the volatility of the mixture in comparison with its purity..?
So, My question is: ...
1
vote
0answers
63 views
Chemical reaction as state transition?
When considering diffusion of chemicals, the reaction part is business of chemical kinetics, where the relevant characteristics of different substances come from collision theory together with some ...
1
vote
1answer
91 views
What's the common consensus on the meaning of “physical change”?
I'm doing a textbook problem that shows a "molecular level" view of some matter, little colored balls, before and after, and there are, among the four questions, two that say: 1) Did a physical change ...
11
votes
2answers
2k views
Why do grapes in a microwave produce plasma?
Some of you may know this experience (Grape + Microwave = Plasma video link):
take a grape that you almost split in two parts, letting just a tiny piece of skin making a link between each half-part.
...
0
votes
1answer
108 views
Electrical Resistance and chemistry
Can some one describe or explain what happens when too much current is passed through lets say a copper wire, I am looking for an explanation to do with physics and chemistry.
For instance we have ...
2
votes
2answers
78 views
Driving a solution of optical isomer molecules with the resonant frequency
What happens when we drive a solution of optical isomer molecules (enantiomers) with a microwave radiation in resonance with the tunneling frequency of the molecules (the frequency of the transition ...
3
votes
1answer
152 views
Why do hydrogen atoms attract?
That is, why is the potential energy with the orbitals overlapping less than with the Hydrogen atoms 'independent'.
Similarly, why is a noble gas configuration stabler than if an electron were to be ...
1
vote
2answers
76 views
Atomic layer deposition applications?
What unexplored areas (known unknowns) are there in atomic layer deposition (ALD)? What unexplored applications of ALD are there? It seems like people use it a lot for coatings of either insulators or ...
4
votes
0answers
87 views
Handling halogen lamps
When consulting manuals, electricians, online sources, etc., they always instruct you to handle halogen light bulbs with gloves.
The "explanation" that usually accompanies this statement is that oils ...
0
votes
1answer
41 views
Is it possible to make use of paper/bill permeate by chemical compound to became a paper-made bullet-proof vest?
Is it possible to make use of paper/bill permeate by chemical compound to became a paper-made bullet-proof vest?
This is inspired by Greece and Italy tend to have more riot than rest of the Europe ...
1
vote
2answers
477 views
How do I integrate the Poisson equation to determine the electric potential along a particular direction (e.g., $z$)?
This question is a sequel of sorts to my earlier (resolved) question about a recent paper. In the paper, the authors performed molecular dynamics (MD) simulations of parallel-plate supercapacitors, ...
0
votes
2answers
236 views
What's up in this SPAWAR video?
Here is a video presentation of infrared recordings of anomalous heating in a deuterium palladium cell: ( youtube video) (see also this presentation if you want more detail, and have time). There are ...
0
votes
1answer
104 views
How to measure electrical resistance?
Is it possible to theoretically measure the resistance of passing of electrical current through liquid electrolyte (distilled water + NaOH) ?
1
vote
1answer
555 views
Why does burning magnesium explode when sprinkled with water?
Magnesium powder burns extremely well and reaches temperatures of 2500°C. However, attempts to extinguish such a magnesium fire with conventional water (e.g. from a garden hose) only make it worse: ...
3
votes
2answers
178 views
What physical forces give rise to the peculiar bond angle of hydrogen peroxide?
In one of the Periodic Table videos, Prof. Poliakoff shows a model of a hydrogen peroxide molecule and claims that the H-O bonds will always be at right angles to each other. I have a rudimentary ...
1
vote
2answers
1k views
What is the approximate electrical conductivity $\sigma$ of graphene in S/m or S/cm?
I am trying to find an approximate value of the electrical conductivity $\sigma$ of graphene in units of S/m or S/cm. This table on Wikipedia gives $\sigma$ values for a variety of materials ...
5
votes
2answers
227 views
In condensed matter simulations, how is particle number density computed in practice?
I have been reading a recent paper. In it, the authors performed molecular dynamics (MD) simulations of parallel-plate supercapacitors, in which liquid resides between the parallel-plate electrodes. ...
4
votes
3answers
908 views
Why is the canonical ($NVT$) ensemble often used for (classical) molecular dynamics (MD) simulations?
Molecular dynamics (MD) simulation is a common approach to the (classical) many-body problem. It relies on integration of Newton's equations of motion to simulate the trajectories of many (e.g., ...
