Percentage Yield

Specification Point 1.30:

Calculate Percentage Yield

Percentage Yield: Calculation of the percentage of yield obtained from the theoretical yield. In practice, some product will be lost during the process when purifying the product by filtration or evaporation or when transferring a liquid or when heating.

Equation:

Percentage Yield     =    ( Yield Obtained / Theoretical Yield ) x 100

Example:

In an experiment to displace copper from copper sulfate, 6.5 g of Zinc was added to an excess of copper (II) sulfate solution. The copper was filtered off, washed and dried. The mass of copper obtained was 4.8 g. Calculate the percentage yield of copper.

Equation Of Reaction:    Zn (s)    +    CuSO₄ (aq)     →     ZnSO₄ (aq)    + Cu (s)

Step 1: Calculate the Amount, in Moles of Zinc Reacted

              Moles of Zinc = 6.5 ÷ 65 = 0.10 moles

Step 2: Calculate the Maximum Amount of Copper that could be Formed

              Maximum Moles of Copper = 0.10 moles

Step 3: Calculate the Maximum Mass of Copper that could be Formed

              Maximum Mass of Copper = ( 0.10 x 64 ) = 6.4 g

Step 4: Calculate the Percentage of Yield of Copper

              Percentage Yield = ( 4.8 ÷ 6.4 ) x 100 = 75%

               Percentage Yield of Copper = 75%