Compare with zero order reaction and second order reaction . The sum of concentration exponents in the rate law for a first order reaction is one. Many radioactive decays are first order reactions. The half life of a reaction is the time required for the amount of reactant to drop to one half its initial value. A highly reactive substance that forms and then reacts further during the conversion of reactants to products in a chemical reaction.
Intermediates never appear as products in the chemical equation for a net chemical reaction .
The order of a reaction is the sum of concentration exponents in the rate law for the reaction. Noninteger orders are possible. Rate constants are independent of concentration but depend on other factors, most notably temperature. A rate law or rate equation relates reaction rate with the concentrations of reactants, catalysts, and inhibitors. A list of all elementary reactions that occur in the course of an overall chemical reaction .