We know that the law of conservation of mass states that mass can neither be created nor destroyed. thus, in chemical reaction , the total mass of the reactants should be equal to the total mass of the products. this means that the total number of atoms of each element should be equal on both side of a chemical equation. such an equation is called a balanced chemical equation, and the method by which it is obtained is called balancing of chemical equations. Hence, an equation having an equal number of atoms of each elements on both the sides is called a balanced chemical equation.
for example :- Zn+2 H CL = Zn Cl₂+H₂