Entropy of Phase Change

Constant Temperature

ΔSphase =
   q(reversible)
= ΔH(phase)
T
T phase

Reversible Process if takes place at NBP, NMP or NSP.

Calculate the entropy change of 18.02 g of water when it is condenses at its boiling point.

Calculate the entropy change of 1 mole of ammonia when it melts at one atmosphere, NBP = –330C.