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When a catalyst is involved in the collision between the reactant molecules, less energy is required for the chemical change to take place, and hence more collisions have sufficient energy for reaction to occur. The reaction rate therefore increases.Collision theory is closely related to chemical kinetics.hen a catalyst is involved in the collision between the reactant molecules, less energy is required for the chemical change to take place, and hence more collisions have sufficient energy for reaction to occur. The reaction rate therefore increases. Collision theory is closely related to chemical kinetics.
1 A physical change, such as a state change or dissolving, does not create a new substance, but a chemical change does. 2  In a chemical reaction, the atoms and molecules that interact with each other are called reactants. 3  In a chemical reaction, the atoms and molecules produced by the reaction are called products.xplain that in most chemical reactions, two or more substances, called reactants, interact to create different substances called products. Tell students that burning a candle is an example of a chemical reaction.