1 Percent Yield

2 Theoretical, Actual, and Percent Yield Theoretical yield The maximum amount of product calculated using the balanced equation. Actual yield The amount of product obtained when the reaction takes place. Percent yield The ratio of actual yield to theoretical yield. percent yield = actual yield (g) x 100 theoretical yield (g)

3 To calculate the percent yield, the actual yield and theoretical yield are needed. Theoretical yield 60 cookies possible (5 dozen) Actual yield 48 cookies to eat Percent yield 48 cookies x 100 = 80% yield 60 cookies Calculating Percent Yield

4 Typical question Without proper ventilation and limited oxygen, the reaction of carbon and oxygen produces carbon monoxide. 2C(g) + O 2 (g) 2CO(g) What is the percent yield if 40.0 g CO are produced when 30.0 g O 2 are used? 1) 25.0% 2) 75.0% 3) 76.2%

5 Write the balance equation Calculate the theoretical yield Identify the actual yield

6 Learning Check Without proper ventilation and limited oxygen, the reaction of carbon and oxygen produces carbon monoxide. 2C(g) + O 2 (g) 2CO(g) What is the percent yield if 40.0 g CO are produced when 30.0 g O 2 are used? 1) 25.0% 2) 75.0% 3) 76.2%

7 Solution 3) 76.2 % yield theoretical yield of CO 30.0 g O 2 x 1 mol O 2 x 2 mol CO x g CO g O 2 1 mol O 2 1 mol CO = 52.5 g CO (theoretical) percent yield 40.0 g CO (actual) x 100 = 76.2 % yield 52.5 g CO (theoretical)

8 Learning Check When N 2 and 5.00 g H 2 are mixed, the reaction produces 16.0 g NH 3. What is the percent yield for the reaction? N 2 (g) + 3H 2 (g) 2NH 3 (g) 1) 31.3 % 2) 56.5 % 3) 80.0 %

9 Solution 2) 56.5 % N 2 (g) + 3H 2 (g) 2NH 3 (g) 5.00 g H 2 x 1 mol H 2 x 2 mol NH 3 x g NH g H 2 3 mol H 2 1 mol NH 3 = 28.2 g NH 3 (theoretical) Percent yield = 16.0 g NH 3 x 100 = 56.7 % 28.2 g NH 3

Percent Yield and Limiting Reactants

A. Percent Yield calculated on paper measured in lab or given in question

Limiting Reactant Steps (version 2) Step 1 Write a balanced equation Step 2 Split the question Step 3 Solve both questions Step 4 Lowest is limiting