Chemical reaction is a process of transformation of one chemical compound to another compound. It includes exothermic and endothermic reaction. There are total five types of chemical reaction. First Synthesis means one or two simpler compound reacts to form a more complicated compound. Second is Combustion where oxygen reacts with compound to form water and carbon dioxide. In this reaction heat is generated so it is called as exothermic reaction. Third decomposition means a complex molecule breaks down in a single compound where energy is required to break down the molecule so it is called as endothermic reaction. Forth single displacement means one element replaces by another in a compound. Last Double displacement means two different molecules switch places to form two entirely different compounds.

In Chemical reaction, the concentration of reactant and products shows no net change over the time is called as chemical equilibrium. At this stage the rate of forward reaction is similar to rate of backward reaction. There is no net change in the concentration of reactants and products and called as equilibrium state. The measurement of equilibrium concentration is expressed as equilibrium constant. At equilibrium the rates of the forward and reverse processes are identical, but the rate constants are generally different. If there is a change in pressure, temperature or number of moles of components, then the net results of reaction changes, which is called as Le Châtelier principle.