In this lesson our instructor talks about stoichiometry. First, he discusses mole to mole ratios and mass to mass conversion. Then he talks about limiting reactants and percent yields. He ends the lesson with a summary and three helpful sample problems. Stoichiometry I Stoichiometry uses coefficients from a balanced chemical equation as a conversion factor to relate any (2) reactants and/or products. Mole to mole ratios are central to any stoichiometry problem. The limiting reagent or reactant dictates how much product is expected to form (known as the theoretical yield). Molarity expresses solution concentration, and can be used as a conversion factor. Acid-base titrations are used to determine (or standardize) the concentration of an unknown solution.