Collision Theory and Concentration

Concentration is defined as the number of molecules of reactants per unit volume. The more the concentration of reactant molecules, more is the probability of collision due to their sheer number.

Increasing the concentration of reactant molecules may or may not increase the rate of chemical reaction. It depends on the particular chemical reaction.
Therefore, collision theory explains the affect of increasing concentration on the rate of a reaction by:

• at higher concentrations there are more particles moving in a confined area, this increased movement will increase the number of collision that can occur