Heat applied to reactant causes a faster chemical reaction. Heat is considered as ACTIVATION ENERGY.
Activation energy is the minimum amount of energy which reactants must possess in order to undergo a chemical reaction. When heat is applied to a particular set of reactants, the heat increases the kinetic energy of the reacting particles, thus enabling them to move around more rapidly. This increases the rate of collision among the reacting particles and empower the reacting particles to overcome the energy barriers and to form the products.