Just by merely looking at the two sides(Reactant and Product sides), the balancing of the elements can be done. This is suitable for simple equations. $$Example 1: \hspace{1cm} CaCO_3 + H_2SO_4 \rightarrow CaSO_4 + CO_2 + H_2O$$ Looking to the two sides, we find that the equation is already balanced. The numbers atoms of all the elements are already equal on the two sides. So nothing more is to be done. $$Example 2: \hspace{1cm} FeCl_3 + NaOH \rightarrow Fe(OH)_3 + NaCl \hspace{1cm} (unbalanced equation)$$ Looking to LHS and RHS, we find that Fe and Na elements are already balanced. Only Cl and OH are not. Both will be balanced together if we make the coefficients of both NaOH a NaCl equal to 3. $$FeCl_3 + 3NaOH \rightarrow Fe(OH)_3 + 3NaCl \hspace{1cm} (balanced equation)$$ $$Example 3: \hspace{1cm} Pb(NO_3)_2 \rightarrow PbO + NO_2 + O_2 \hspace{1cm} (unbalanced equation)$$ On inspection, we find that Pb is