 Product Yields in Chemical Reactions The amount of material produced in a chemical reaction, called the yield of the reaction, depends on both the quantities of the reactants chemicals used and whether the reaction goes to completion. The theoretical yield, the maximum amount of product that can be produced, is predicted from the amount of reactants used and the mole ratio of products to reactants shown by the balanced equation. The actual yield, which is the amount of product isolated, is usually less than the theoretical yield. The percent yield is calculated using the following equation. Here's an example. 15.6 grams of benzene react with excess nitric acid to produce 18 grams of nitrobenzene. Calculate the percent yield. The balanced equation is shown below. Step 1. Calculate the theoretical yield of nitrobenzene based upon the limiting reagent benzene. We take the 15.6 grams of benzene from the question, convert to moles, convert substances, and convert to grams. Step 2. Calculate the percent yield of nitrobenzene. Our percent yield is 73.2 percent. Here's a question. Which is the best definition of actual yield? A. The weight of product produced. B. The weight of reactant used. Or C. The weight of product predicted. The answer is A. The weight of product produced. The actual yield is the quantity of product produced by a chemical reaction. Let's try a few more questions. Question of 2.85 grams of ethane with excess chlorine produces 12.5 grams of 1-1-2-2 tetrachloroethane. What is the actual yield in grams? If you said 12.5 grams, that's correct. What is the number of moles of ethane used to three significant figures? If you said 0.102 mole, that's correct. Here's another question. Which is the best definition of theoretical yield? A. The weight of product produced. B. The numbers of moles of product produced. Or C. The weight of product predicted. If you said C, that's correct. The theoretical yield is the weight of the product predicted. What is the theoretical number of moles of 1-1-2-2 tetrachloroethane produced to three significant figures? If you said 0.102 mole, that's correct. What is the theoretical yield of 1-1-2-2 tetrachloroethane produced in grams to three significant figures? 17.3 grams, that's correct. What is the percent yield? 72.3 percent. Congratulations! You have completed this activity. Product yields in chemical reactions.