Find the change in entrophy when 1.25 kg of steam at 100C condense and cools to 50 C

Answer 1

condensation:
dS = n*q/T. Look up heat vaporization. T will be 373.15
for change in T from 100 C to 50 C:
dS = n*Cp*ln(T2/T1) . Use both T values in kelvin.