Question

What is a chemical equation ? Why it is necessary to balance it.

Answer 1

A chemical equation is a symbolic representation of a chemical reaction. Here we use symbols and formulas of the substance involved in the reaction.
According to law of conservation of mass, "matter can neither be created nor be destroyed in a chemical reaction.This is possible only, if total number of atoms on the reactants side is equals to total number of atoms on products side. Thus, a chemical reaction should be always balanced.