How does stoichiometry relate the amounts of reactants and products?

Stoichiometry is the branch of chemistry that determines the proportions in which elements or compounds react with one another. It provides the quantitative relationship between the amounts of reactants consumed and the products formed in a chemical reaction.13

These relationships are governed by the law of conservation of mass, which dictates that matter cannot be created or destroyed during a reaction. Consequently, chemical equations must be balanced to ensure the same number of atoms of each element appears on both sides.123

The coefficients in a balanced equation serve as stoichiometric factors, indicating the specific ratio of molecules required for the reaction. Because matter is conserved, chemists use these ratios alongside the concept of the mole to calculate the precise mass relationships between substances. If the amount of one reactant is changed, stoichiometry allows for the determination of how much of another reactant is needed or how much product will be generated, accounting for the limiting reagent that restricts the total yield.23