Which of the phase changes below might have a H = 11.6 kJ·mol-1?
a) condensation
b) evaporation
c) deposition
d) freezing
b) evaporation
Answer: As dH is positive, the phase change must be an endothermic process (requiring the input of heat). Of the answer choices, only evaporation takes place when heat is added to the system. The others require the removal of heat.