A chemical equation is a symbolic representation of a chemical reaction, illustrating the substances that participate in a chemical change and the resulting products. It uses chemical formulas and state symbols to denote the reactants and products involved. According to the law of conservation of mass, any accurate chemical equation must be balanced, meaning the total number of atoms for every element must be equal on both the reactant and product sides. This balancing is achieved by placing numerical coefficients before the chemical formulas, which provide a stoichiometric ratio defining the quantitative relationship between the amounts of substances consumed and produced during the reaction.