Energy is released during which phase changes?

There are two phase changes where the heat energy is released: Condensation: When gas condenses to liquid the quantity of energy converted from chemical to heat is called the Heat of Vaporization or Δ Hvap .

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.