Calculating Percent Yield

Calculating percent yield means first finding the theoretical yield from the limiting reactant, then dividing the reaction's actual, measured yield by that theoretical value and multiplying by 100.

Reacting 32.9 g of CCl4 with excess HF is predicted, from the balanced equation and CCl4's identity as the limiting reactant, to give a theoretical yield of about 25.9 g of the product CF2Cl2. If the reaction actually produces 12.5 g of CF2Cl2 once isolated and weighed, dividing 12.5 g by 25.9 g and multiplying by 100 gives a percent yield of about 48.3%, well below the theoretical ceiling.