Thermodynamics, Statistical Physics, and Quantum Mechanics

It can be easily seen that thepressure becomes so

135

and

Let us show that isalways nonnegative. This isequivalent to the

condition

Chemical Potential of Ideal Gas (Stony Brook)

The expressionfor the Helmholtzfreeenergy was derived in Problem4.38:

Since all the molecules are in theground state, the sumonly includes one
term, whichwe can take as an energy zero, Then(S.4.39.1)becomes

where we took into account a degeneracy of the ground state TheGibbs
freeenergyGis then

which is alwaystrue. At whichmakesperfect
sense.

4.39

THERMODYNAMICS AND STATISTICAL PHYSICS