Glossary of Words

Summary and Key Ideas

Reaction Stoichiometry

A balanced chemical equation may be used to describe a reaction’s stoichiometry (the relationships between amounts of reactants and products). Coefficients from the equation are used to derive stoichiometric factors that subsequently may be used for computations relating reactant and product masses, molar amounts, and other quantitative properties.

Reaction Yields

When reactions are carried out using less-than-stoichiometric quantities of reactants, the amount of product generated will be determined by the limiting reactant. The amount of product generated by a chemical reaction is its actual yield.

This yield is often less than the amount of product predicted by the stoichiometry of the balanced chemical equation representing the reaction (its theoretical yield). The extent to which a reaction generates the theoretical amount of product is expressed as its percent yield.

Key Equations

  • \(\text{percent yield} = \left ( \cfrac{\text{actual yield}}{\text{theoretical yield}} \right ) × 100\)


Actual yield

amount of product formed in a reaction

Excess reactant

reactant present in an amount greater than required by the reaction stoichiometry

Limiting reactant

reactant present in an amount lower than required by the reaction stoichiometry, thus limiting the amount of product generated

Percent yield

measure of the efficiency of a reaction, expressed as a percentage of the theoretical yield

Stoichiometric factor

ratio of coefficients in a balanced chemical equation, used in computations relating amounts of reactants and products


relationships between the amounts of reactants and products of a chemical reaction

Theoretical yield

amount of product that may be produced from a given amount of reactant(s) according to the reaction stoichiometry

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