1. Chapter 12 Stoichiometry Part 3

2. PERCENT YIELD Most reactions never succeed in producing the predicted amount of product. So in order to determine the success of a reaction, the percent yield is calculated.

3. Comparing the actual quantitative results of a chemical rxn to the theoretical (calculated) maximum. Why? * to determine if a method of manufacturing a product is profitable or another method works better

4. Usually the % yield is less than 100 b/c product is lost somewhere along the way or the reaction wasnt complete. Occasionally the % yield is above 100 if the product is contaminated or if moisture is absorbed b/c of high humidity.

5. % yield = actual yield x 100 theoretical yield theoretical maximum amount of product that can be produced from a given amount of reactant in a chemical equation actual the amount of product actually produced when the chemical reaction is carried out in an experiment

6. Examples When 24.8g of calcium carbonate is decomposed by heating, 13.1g of calcium oxide forms along with some CO 2. What is the % yield of this rxn?

7. Example What is the percent yield if 3.74g of copper are produced when 1.87g of Al are reacted with an excess of copper II sulfate? 2Al + 3CuSO 4 Al 2 (SO 4 ) 3 + 3Cu

8. Example What is the percent yield if 56.15g of Na reacts with an excess of Cl 2 and yields 136.2g of sodium chloride?

9. Example If the decomposition of magnesium chlorate is 92.3% efficient, how many grams of magnesium chlorate are needed to produce 428.4 g of magnesium chloride?