“Chemical Kinetics is the branch of chemistry that deals with the study of the rates of chemical reactions and with the elucidation of the mechanisms by which they proceed.
The velocity or rate is expressed in terms of change in concentration of one of the reactants or products per unit of time. Examples are:
Reactions involving ions are instantaneous: The neutralization of a strong acid and a strong base.
The detonation of glyceryl trinitrate, an explosive occurs within a millionth of a second.
The decomposition of dinitrogen pentoxide (N2O5) to NO2 and O2 is as follows:
2N2O5 → 4NO2 + O2
Let the concentration of N2O5 be at an instant: 5 mol/litre, which become 2.6 mol/litre after ½ hour.