Unbalanced chemical equation of synthesizing cryolite:
Al₂O₃ + NaOH + HF → Na₃AlF₆ + H₂O.
Balanced chemical equation:
Al₂O₃ + 6NaOH + 12HF → 2Na₃AlF₆ + 9H₂O.
According to principle of mass conservation, number of atoms must be equal on both side of balanced chemical reaction.
There are two aluminium atoms (Al), six sodium atoms (Na), eighteen hydrogen atoms (H), nine oxygen atoms (O) and twelve fluorine atoms (F) on both side of balanced chemical reaction.