The phase of a reactant or a product are often indicated in parentheses according to the abbreviations presented in the chart below.
Below is a recipe for balancing a reaction.
(1) Choose some reactant or product as a 'base' and set its coefficient to 1. Avoid choosing a base that contains any element that appears in multiple species on the opposite side of the reaction.
(2) On the opposite side of the reaction, adjust the coefficient of the species containing elements appearing only in those species and in the base.
(3) Balance other species which contain elements which appear only once on each side of the reaction.