Oct 4, 2015

By the addition of subscripts, (s), (l), (g), that identify the state of reactant or product; by the addition of thermodynamic parameters.

Explanation:

Quite clearly, inclusion of the physical states of reactants and products is desirable. So too is the inclusion of thermodynamic parameters, $\Delta H$, $\Delta S$, ${K}_{e q}$, etc. Balanced equations (LHS = RHS) are absolutely essential.