The
rate of reaction can be calculated from the change in concentration of a reactant or product with time.
The
differential rate law for a reaction is the mathematical relationship between reaction rate and the concentration of substances, upon which rate depends.
General form of differential rate law:
rate = k[A]x[B]y.x and y are experimentally determined.
k, the rate constant, is constant for a reaction at a temperature.
The unit of k depends on the powers of concentrations in the rate law.
If the differential rate law is known
the rate of reaction at a particular temperature can be calculated for given concentrations provided the rate constant at the temperature is known.
it is possible to predict how the rate changes when concentrations of substances appearing in the rate law are changed.
For example, for the reaction that has the rate law: rate = k[CH3Br][OH–] doubling [OH–] doubles the rate.