Quick reference for common balanced equations.
The law of conservation of mass requires that the same number of each type of atom appears on both sides of a chemical equation. Balancing uses coefficients (not subscripts) to equalize atoms. Steps: (1) Write the unbalanced equation, (2) Count atoms of each element on both sides, (3) Add coefficients starting with the most complex molecule, (4) Balance metals first, then nonmetals, then hydrogen and oxygen last, (5) Verify all atoms balance and coefficients are in the lowest whole-number ratio. For redox reactions, use the half-reaction method: separate into oxidation and reduction half-reactions, balance each for mass and charge, then combine. The coefficient in a balanced equation directly gives the mole ratio used in stoichiometric calculations.