Answer:
According the law of conservation of mass, the mass of the reactant should be equal to the products in an chemical reaction. so we go far balancing the chemical reactions.
1) [tex]S +O_2 \rightarrow SO_2[/tex]
2) [tex]2Na + O_2 \rightarrow Na_2O_2[/tex]
3) [tex]2Hg + O_2 \rightarrow 2HgO[/tex]
4) [tex]2Ag_2O \rightarrow 4Ag + O_2[/tex]
5) [tex]Ba(OH)_2 + H_3PO_4 \rightarrow BaHPO_4+ 2H_2O[/tex]
6) [tex]2NaOH + H_3PO_4 \rightarrow Na_2HPO_4 +2H_2O[/tex]
7) [tex]C_4H_8 + 6O_2\rightarrow 4CO_2+4H_2O[/tex]
8) [tex]C_3H_8 + 5O_2\rightarrow3CO_2+4H_2O[/tex]
9) [tex]2Fe + 3Cl_2\rightarrow 2FeCl_3[/tex]
10) [tex]2Al+6HCl \rightarrow2 AlCl_3 +3H_2[/tex]
11) [tex]2H_2 +O_2 \rightarrow 2H_2O[/tex]
12) [tex]N_2 + 3H_2 \rightarrow 2NH_3[/tex]
