👉 In chemistry, a stoichiometry is a quantitative measure of the number of particles or molecules that must be added to an initial amount of reactant in order to produce a desired final product. This measurement is used to determine the ratio of the quantities of each reactant and the products produced in a balanced chemical reaction. For example, consider the following reaction: 2H2 + O2 → 2H2O In this equation, we have two reactants (H2 and O2