Tagged Questions
3
votes
1answer
158 views
Why is (von Neumann) entropy maximized for an ensemble in thermal equilibrium?
Consider a quantum system in thermal equilibrium with a heat bath. In determining the density operator of the system, the usual procedure is to maximize the von Neumann entropy subject to the ...
1
vote
0answers
38 views
Any new texts directly on second law of thermodynamics? [duplicate]
Possible Duplicate:
Recommendations for Statistical Mechanics book
Is anyone aware of any recent text that summarises the research and arguments on second law of thermodynamics and also on ...
11
votes
5answers
675 views
Why does the nature always prefer low energy and maximum entropy?
Why does the nature always prefer low energy and maximum entropy?
I've just learned electrostatics and I still have no idea why like charges repel each other.
...
0
votes
1answer
69 views
Evolution of Gibbs energy change of reaction with temperature
The Gibbs energy change of reaction is given by $$\Delta G^0_{rx}=\Delta H^0_{rx}-T\Delta S^0_{rx}$$
From the look of it seems the direction of variation of equlibrium with $T$ is given by the sign ...
3
votes
2answers
259 views
Time to establish saturated vapour pressure above liquid
Thought experiment - a liquid is in a closed container in equilibrium with its vapour, and then suddenly all the vapour is pumped away. Switch off the pump so that instantaneosuly there is no vapour ...
3
votes
3answers
160 views
What are some creative illustrations of the nature of dissipative forces?
I'm teaching a conceptual introduction to physics for American 13-15 year old students this summer.
One of the main ideas I want to hit on is the relationship between energy conservation, ...
11
votes
3answers
863 views
Prove that negative absolute temperatures are actually hotter than positive absolute temperatures
Could someone provide me with a mathematical proof of why, a system with an absolute negative Kelvin temperature (such that of a spin system) is hotter than any system with a positive temperature (in ...
3
votes
2answers
172 views
When do thermal and chemical equilibrium not coincide?
What is an example for a system, which is in chemical equilibrium, but not in thermodynamical equilibrium?
And what about the other way around?
It seems to me, that as long as Parameters like ...
5
votes
3answers
2k views
Why does maximal entropy imply equilibrium?
From a purely thermodynamical point of view, why does that entropy have to be a maximum at equilibrium? Say there is equilibrium, i.e. no net heat flow, why can the entropy not be sitting at a ...
8
votes
3answers
180 views
Is “equilibrium state” equivalent to “well-defined state variables”?
Follow up to
Intuitively, why is a reversible process one in which the system is always at equilibrium?
and
How slow is a reversible adiabatic expansion of an ideal gas?
Suppose you have a ...
2
votes
2answers
168 views
why egg cooks slowly in mountains?
A quick Google tells me "Because water boils at a lower temperature at high altitudes". But I am not being able to understand this answer and fill-in the gap. Like, how does an egg cook in the first ...
7
votes
5answers
852 views
How do we perceive hotness or coldness of an object?
Some objects, especially metallic ones, feel cold on touching and others like wood, etc. feel warm on touching. Both are exposed to same environment and are in their stable state, so some kind of ...
4
votes
1answer
140 views
Boltzman distribution for chemical potentials
I read that if we have a system with two co-existing phases with chemical potentials respectively $\mu_1$ and $\mu_2$ then, at the equilibrium, the concentrations $X_1$ and $X_2$ are related by the ...
