Percentage Yield

• Calculating percentage yield for a reaction

  1. Calculate the maximum theoretical mass of product

  2. Calculate the actual mass of product made

  3. Percentage yield = (Actual mass of product / Maximum theoretical mass of product) x 100
• 100% yield means all the reactants have been converted to the expected products
• Reasons why percentage yield may be less than 100%

  • Some product may be lost when separated from the reaction
  • Reactants may react in different ways to the expected reaction
  • Reversible reactions may not go to completion
• Percentage yield cannot be greater than 100%
• If the calculated percentage yield is greater than 100%, it means the calculation has been switched
• Calculating percentage yield for a reaction

  1. Calculate the maximum theoretical mass of product

  2. Calculate the actual mass of product made

  3. Percentage yield = (Actual mass of product / Maximum theoretical mass of product) x 100
• 100% yield means all the reactants have been converted to the expected products
• Reasons why percentage yield may be less than 100%

  • Some product may be lost when separated from the reaction
  • Reactants may react in different ways to the expected reaction
  • Reversible reactions may not go to completion
• Percentage yield cannot be greater than 100%
• If the calculated percentage yield is greater than 100%, it means the calculation has been switched
• Calculating percentage yield for a reaction

  Mass of product actually made / Maximum theoretical mass of product x 100
• We cannot achieve greater than 100% yield as that would mean creating atoms, which is not possible
• Reasons for percentage yield being less than 100%: