1. Stoichiometry and the Math of Equations Part 4: Percent Yield 1

2. Objectives Explain that the final answer to an excess-limiting problem is the theoretical amount of product made Use this knowledge and experimental data to calculate the percentage yield of a reaction 2

3. Percent Yield The final answer to ANY excess-limiting problem is the theoretical yield of product- the amount of product predicted from the amounts of the reactants given –Represents the maximum amount of product that can be made Reality: –The theoretical yield is rarely obtained in a real laboratory setting –Side reactions consume some of the reactants or products 3

4. Percent Yield Percent yield - the actual yield, the amount actually obtained, is often compared to the theoretical yield as a percentage 4

5. Percent Yield 68.5 g of CO is reacted with 8.60 g of H 2 gas to produce methanol (CH 3 OH). If 55.7 g of methanol is actually produced, calculate the % yield of the methanol The formula for calculating percent yield is: –Actual = What you got (experimental) –Theoretical = What you should have gotten in theory (expected) 5

6. 68.5 g of CO is reacted with 8.60 g of H 2 gas to produce methanol (CH 3 OH). If 55.7 g of methanol is actually produced, calculate the % yield of the methanol First – find the theoretical yield (do an excess-limiting problem) 68.5 g 8.60 g ? g CO + 2 H 2 → CH 3 OH 1 mole 2 mole 1 mole 6

7. 68.5 g of CO is reacted with 8.60 g of H 2 gas to produce methanol (CH 3 OH). If 55.7 g of methanol is actually produced, calculate the % yield of the methanol Find out which one is limiting: 68.5g CO x1 mol CO x 2 mol H 2 x 2.02g H 2 1 28.0g CO 1 mol CO 1 mol H 2 = 9.88 g H 2 so H 2 is limiting 8.60g H 2 x 1 mol H 2 x 1 mol CH 3 OH x 32.0g CH 3 OH = 1 2.02g H 2 2 mol H 2 1 mol CH 3 OH = 68.1 g CH 3 OH 7

8. 68.5 g of CO is reacted with 8.60 g of H 2 gas to produce methanol (CH 3 OH). If 55.7 g of methanol is actually produced, calculate the % yield of the methanol Next, find the percent yield: What we got (given in problem) What we should have gotten 8

9. Objectives Explain that the final answer to an excess-limiting problem is the theoretical amount of product made Use this knowledge and experimental data to calculate the percentage yield of a reaction 9