Question

During an endothermic phase change, what happens to the potential energy and the kinetic energy?

Answer 1

Nothing, if held constant. The interaction would imply an increase in potential energy and either an increase or decrease in kinetic energy, depending on the direction of the phase change.

Explanation:

Those are three different ways of indicating a particular energy state of an object. They do not necessarily affect each other.

"Potential Energy" is a relative term indicating a possible release of energy to the surroundings. If we take its baseline as the overall energy state of a compound, then an endothermic phase change would imply an increase in "potential" as energy is being added to the compound by the system.

A phase change will exhibit an increase in the kinetic energy whenever the compound is changing from a more dense to a less dense phase. The kinetic energy will decrease whenever the compound is changing from a less dense to a more dense phase.