The theoretical yield of a reaction is determined only by the amount of the limiting reactant because this reactant is the one that will be completely consumed in the reaction. The other reactants will be present in excess, meaning that there is more of them than is needed to react with the limiting reactant.

The limiting reactant is the one that is present in the smallest mole ratio compared to the other reactants. This can be determined by dividing the moles of each reactant by its stoichiometric coefficient in the balanced chemical equation. The reactant with the smallest mole ratio is the limiting reactant.

Once the limiting reactant has been identified, the theoretical yield can be calculated by multiplying the moles of the limiting reactant by the stoichiometric coefficient of the product in the balanced chemical equation. This will give the maximum amount of product that can be formed in the reaction.

The actual yield of a reaction is usually less than the theoretical yield due to factors such as side reactions, incomplete reactions, and losses during purification. However, the theoretical yield provides a useful reference point for evaluating the efficiency of a reaction.