Which factor does not affect the theoretical yield of a reaction?

The stoichiometry of a reaction refers to the quantitative relationship between the reactants and products in a chemical reaction, based on the balanced chemical equation. It dictates how much of each reactant is required to produce a certain amount of product, thereby establishing the theoretical yield.

Theoretical yield is calculated from the initial amounts of the reactants and their molar ratios derived from the balanced equation. Therefore, while factors like purity of starting materials, temperature, and the presence of a catalyst may influence the actual yield or the rate of the reaction, they do not change the theoretical yield as defined by stoichiometric principles. In other words, the stoichiometry remains constant, regardless of the efficiency or conditions of the reaction, thus it does not affect the theoretical yield.