Percentage Yield | Chemistry for Grade 11 (IGCSE) PDF Download

Calculating Percentage Yield 

• Yield refers to the quantity of product obtained from a chemical reaction.
• Achieving 100% yield in a chemical process is not feasible in practical scenarios due to various factors.
• These factors encompass:
  • Residual reactants may remain in the apparatus after the reaction.
  • Reversible reactions impede high yields as products revert to reactants continuously.
  • Loss of products might occur during separation and purification procedures like filtration or distillation.
  • Side reactions may transpire where a substance interacts with ambient gases or impurities within the reactants.
  • Product losses can transpire during the transfer between containers.

Actual & Theoretical Yield

• Actual yield denotes the measured quantity of product acquired from a reaction.
• Theoretical yield represents the anticipated amount of product achievable under ideal practical and chemical circumstances, calculated based on the balanced equation and reactant masses.
• Percentage yield serves as a comparison between the actual yield and the theoretical yield.
• In pursuit of economic efficiency, chemical manufacturing companies aim for a high percentage yield to enhance profits, minimize expenses, and mitigate waste.
• The formula for calculating percentage yield is as follows:
  

Calculating percentage mass 

• Sometimes, you might need to determine the percentage by mass of an element in a compound.
• This involves computing the relative formula mass of the compound.
• The calculation requires using the following equation:
  

Calculating Percentage Purity

• Pure substances contain no other substances mixed with them.
• However, the product you aim to obtain might become tainted with undesirable substances like unreacted reactants, catalysts, or impurities.
• To determine the percentage purity, you use the following equation: