Question

why does phase change occur

Answer 1

Answer:

A phase change is when matter changes to from one state (solid, liquid, gas, plasma) to another. (see figure 1). These changes occur when sufficient energy is supplied to the system (or a sufficient amount is lost), and also occur when the pressure on the system is changed.

Answer 2

Answer:

Phase changes require either the addition of heat energy (melting, evaporation, and sublimation) or subtraction of heat energy <condensation and freezing>.

Explanation:

Changing the amount of heat energy usually causes a temperature change.