1,067 reputation
25
bio website scholar.chem.nyu.edu
location New York, United States
age 81
visits member for 2 years, 4 months
seen Aug 17 '13 at 0:56

I am a retired teacher of chemistry at the university level. My particular fields are thermodynamics and statistical mechanics. From being retired it is possible to infer that I'm one of the over-the-hill gang. One might be right about that, I'm the wrong person to ask.


Jul
2
awarded  Yearling
Aug
17
answered Derivation of Pressure/Kinetic Therory problem involving hole in box
Aug
15
answered Can a liquid shrink as something is dissolved into it?
Jul
2
awarded  Yearling
Jun
17
answered Where did Schrödinger solve the radiating problem of Bohr's model?
Jun
17
comment What is the deal with heat capacity?
I'm sorry, the answer above is incomplete, but I timed out before I could fix it. what it should say is: Well, no. Almost all differentials are "inexact" and they are written with a "d" or a "$\partial$". And Q occurs in a number of thermodynamic equations such as the balance principle in the first law $dE = dQ - pdV$, which you have used above, and the definition of entropy. Further, the general definition of the heat capacity is $\partial Q/\partial T$ with the appropriate quantities held constant.
Jun
17
comment What is the deal with heat capacity?
Well, no. Almost all differentials are "inexact" and they are written with a "d" or a "$\partial$". And Q occurs in a number of thermodynamic equations such as the balance principle in the first law $dE = dQ - pdV$ and the definition of entropy. Further, the general definition of the heat capacity is $
Jun
16
answered What is the deal with heat capacity?
Jun
16
comment Can a object with constant acceleration change its trajectory?
But wasn't the question about constant acceleration?
Jun
6
comment How to reconcile the two definitions of work? (mechanical and thermodynamical)
I do think you are making a mistake. The definition of infinitesimal work is unambiguously the dot product of the force vector and the infinitesimal distance vector. The mistake you are making is that the work is being done on (or done by) the WEIGHTS on the massless piston. I do not know what other definition of work one can use. We are not calculating the work done on or by the piston itself.
Jun
6
comment Schrodinger's cat experiment
The cat is not an observer for all the reasons already given plus the fact that the cat cannot communicate what it observes to us. So the cat can be ignored. But I repeat my statement above involving two sets of observers, one able to see the cat, the other not. For the observers that see the cat, there is no superposition. If the cat dies, a transition between the life and death states is seen. Otherwise the cat continues alive. The conclusion to all this is that the state function reflects the observer's knowledge and NOT necessarily objective reality.
Jun
4
answered Why does the Boltzmann factor $e^{-E/kT}$ seem to imply that lower energies are more likely?
Jun
4
answered How to reconcile the two definitions of work? (mechanical and thermodynamical)
May
21
comment Isothermal Gas Expansion, a Reversible or Irreversible process?
I have an error in the above answer. There should be a minus sign in front of the integral. That said, the physical and thermodynamic definition of work is as I have it in the equation. IF the process is reversible, then and only then can the external pressure be replaced by the internal pressure since the two are the same. As for your point about the Q's, please note that your process is not a cycle.
May
21
answered Question about the proof that heat capacity goes to zero if temperature approaches $0K$
May
20
answered Isothermal Gas Expansion, a Reversible or Irreversible process?
May
10
comment Does the collapse of the wave function increase entropy of the atomic system itself?
Unexplained downvotes ought to be forbidden. The person who answers sticks their necks out but the people who downvote get to be anonymous. Doesn't seem fair.
May
4
answered What counts as “observation” in Schrödinger's Cat, and why are superpositions possible?
Apr
26
comment How is it possible to equate the internal energy at constant volume with the internal energy of an adiabatic process?
@joshphysics is quite right. I add two notes. One is that the resulting formula hold ONLY for ideal gases. The other is that in $w = -pdV$, $p$ is the internal pressure ONLY if the process is reversible, because only then are the internal and external pressures equal.
Apr
25
comment The notion of an adiabatic process in thermodynamics -vs- quantum mechanics
I agree with @joshphysics. In chemistry it is unambiguous that "adiabatic" means "thermally isolated". Thus an explosion, at least in its initial stages, can be and is treated as adiabatic because there is not enough time to exchange much heat with the surroundings. Further, adiabatic processes do NOT have to be at or near equilibrium. Those paths are called "reversible". Adiabatic paths can be reversible but are not mandated to be such.