Chapter 9 Chemical Quantities in Reactions 9.4 Percent Yield Learning Goal Given the actual quantity of product, determine the percent yield for a reaction. © 2014 Pearson Education, Inc.

Percent yield is the ratio of actual yield to theoretical yield. Theoretical yield is the amount of product we expect, if all the reactants were converted to the desired product. Actual yield is the amount of product obtained when the reaction takes place. Percent yield is the ratio of actual yield to theoretical yield. © 2014 Pearson Education, Inc.

Calculating Percent Yield On a space shuttle, LiOH is used to absorb exhaled CO2 and form LiHCO3. LiOH(s) + CO2(g)  LiHCO3(s) On a space shuttle, the LiOH in the canisters removes Co2 from the air.

Calculating Percent Yield What is the percent yield of LiHCO3 if 50.0 g of LiOH produces 72.8 g of LiHCO3? LiOH(s) + CO2(g)  LiHCO3(s) Step 1 State the given and needed quantities. Given: 50.0 g of LiOH, 72.8 g of LiHCO3 Need: Theoretical yield, LiHCO3 Percent yield, LiHCO3

Calculating Percent Yield LiOH(s) + CO2(g)  LiHCO3(s) 50.0 g 72.8 g Actual yield ? Theoretical yield Step 2 Write a plan to calculate the theoretical and percent yield. grams of LiOH moles of LiOH moles of LiHCO3 grams of LiHCO3 Molar Mass Mole–Mole factor Molar Mass

Calculating Percent Yield LiOH(s) + CO2(g)  LiHCO3(s) 50.0 g 72.8 g Actual yield ? Theoretical yield Step 3 Write the molar mass and mole−mole factors. 1 mole of LiOH = 23.95 g of LiOH

Calculating Percent Yield LiOH(s) + CO2(g)  LiHCO3(s) 50.0 g 72.8 g Actual yield ? Theoretical yield Step 3 Write the molar mass and mole−mole factors. 1 mole of LiHCO3 = 67.96 g of LiHCO3

Calculating Percent Yield LiOH(s) + CO2(g)  LiHCO3(s) 50.0 g 72.8 g Actual yield ? Theoretical yield Step 3 Write the molar mass and mole−mole factors. 1 mole of LiOH = 1 mole of LiHCO3

Calculating Percent Yield LiOH(s) + CO2(g)  LiHCO3(s) 50.0 g 72.8 g Actual yield ? Theoretical yield Step 4 Calculate the percent yield by dividing the actual yield by the theoretical yield and multiplying by 100%. Calculation of theoretical yield:

Calculating Percent Yield LiOH(s) + CO2(g)  LiHCO3(s) 50.0 g 72.8 g Actual yield ? Theoretical yield Step 4 Calculate the percent yield by dividing the actual yield by the theoretical yield and multiplying by 100%. Calculation of theoretical yield:

Learning Check Without proper ventilation and limited oxygen, the reaction of carbon and oxygen produces carbon monoxide. 2C(g) + O2(g)  2CO(g) What is the percent yield if 40.0 g of CO is produced when 30.0 g of O2 is used?

Step 1 Write the given and needed quantities. Solution What is the percent yield if 40.0 g of CO is produced when 30.0 g of O2 is used? 2C(g) + O2(g)  2CO(g) 30.0 g 40.0 g Actual yield ? Theoretical yield Step 1 Write the given and needed quantities. Given: 30.0 g of O2, 40.0 g of CO Need: Theoretical yield, CO Percent yield, CO

Step 2 Write a plan to calculate the theoretical and percent yield. Solution 2C(g) + O2(g)  2CO(g) 30.0 g 40.0 g Actual yield ? Theoretical yield Step 2 Write a plan to calculate the theoretical and percent yield. Molar Mass Molar Mass Mole–Mole factor grams of O2 moles of O2 moles of CO grams of CO

Step 3 Write the molar mass and mole– mole factors. Solution 2C(g) + O2(g)  2CO(g) 30.0 g 40.0 g Actual yield ? Theoretical yield Step 3 Write the molar mass and mole– mole factors. 1 mole of O2 = 32.00 g of O2

Step 3 Write the molar mass and mole– mole factors. Solution 2C(g) + O2(g)  2CO(g) 30.0 g 40.0 g Actual yield ? Theoretical yield Step 3 Write the molar mass and mole– mole factors. 1 mole of CO = 28.01 g of CO

Step 3 Write the molar mass and mole– mole factors. Solution 2C(g) + O2(g)  2CO(g) 30.0 g 40.0 g Actual yield ? Theoretical yield Step 3 Write the molar mass and mole– mole factors. 1 mole of O2 = 2 moles of CO

Solution 2C(g) + O2(g)  2CO(g) 30.0 g 40.0 g Actual yield ? Theoretical yield Step 4 Calculate the percent yield by dividing the actual yield by the theoretical yield and multiplying by 100%. Calculation of theoretical yield:

Solution 2C(g) + O2(g)  2CO(g) 30.0 g 40.0 g Actual yield ? Theoretical yield Step 4 Calculate the percent yield by dividing the actual yield by the theoretical yield and multiplying by 100%. Calculation of theoretical yield: