How can you tell how many compounds are required in a reaction?

To determine how many compounds are required in a reaction, start by analyzing the balanced chemical equation, which shows the reactants and products involved. Count the distinct substances on the reactant side; each unique compound corresponds to a required reactant. Additionally, consider the stoichiometry of the reaction, which indicates the molar relationships between reactants and products, providing insight into how many of each compound are needed for the reaction to proceed.