CH353 - Physical Chemistry I
Spring 2015, Unique 51170

Lecture Summary, 12 February 2015


Entropy of phase transitions: Phase transitions are to a good approximation reversible processes.  Therefore, we can estimate the heat involved in a phase transition, q(trans) = deltaH(trans).  The change in entropy of the system is therefore

  deltaS(trans) = deltaH(trans)/T

Entropy of Mixing:  If two gasses at the same T and P are separated by a partition, and if that partition is removed, the gasses will mix spontaneously.  The change in entropy of the system is

  deltaS(mix) = -n(2)Rln(V2/Vf) + -n(1)Rln(V1/Vf)