The reaction rate constant k is calculated by the formula v = k [c (a)] n [c (b)] m. In chemical kinetics, the reaction rate constant is also called the rate constant k, which is a quantitative expression of the chemical reaction rate. Exponents m and n are called reaction order and depend on the reaction mechanism. It can be determined by experiments.

Reaction rate is the speed of chemical reaction, and the unit is mole/(L s) or mole/(L min). It is expressed by the decrease of reactant concentration or the increase of product concentration per unit time. Chemical reactions do not proceed at a uniform speed: the reaction rate can be divided into average rate (average reaction rate in a certain time interval) and instantaneous rate (reaction rate at a given moment), which can be determined by experiments.