Question

Freezing involves a chemical reaction

Answer 1

The two main chemical reactions that are involved in the change of state are exothermic reaction and endothermic.
Just as their name suggests, endothermic is when heat is ‘taken in’ and exothermic when heat is ‘given out’.
Freezing is not a CHEMICAL CHANGE, but indeed a physical one because it goes through change of state.
So in freezing a liquid converts to a solid.
For this change to happen, temperatures need to be lower and molecules in the liquid require less energy to join together, so it releases energy in the form of heat.
This reaction will be known as EXOTHERMIC REACTION.

Answer 2

The same argument can be made for the process of freezing: energy is put into a liquid during melting, so freezing the liquid into a solid again returns that energy to the surroundings. Like phase changes, chemical reactions can occur with the application or release of heat.