Overview
This lecture explains the concepts of yield in chemical reactions, reasons for reduced yield, and how to calculate percentage yield.
Types of Yield in Chemical Reactions
- The yield is the amount of product obtained from a chemical reaction, measured in grams or moles.
- Actual yield is the amount of product actually obtained in an experiment.
- Theoretical yield is the calculated amount of product expected based on stoichiometry.
Reasons for Lower Actual Yield
- some reactants may not fully react, leaving unreacted materials due to slow reactions or equilibrium in reversible reactions.
- Side reactions can cause reactants to produce unwanted products, reducing the amount of desired product.
- Physical loss of product can occur when products escape as gas or some remain on equipment during transfer or filtration.
Calculating Percentage Yield
- Percentage yield quantifies how much product was actually made compared to the theoretical maximum.
- The formula for percentage yield is:
Percentage yield = (actual yield ÷ theoretical yield) × 100
- Example: If actual yield is 15 g and theoretical yield is 18 g, percentage yield = (15 ÷ 18) × 100 = 83.3%.
Key Terms & Definitions
- Yield — the amount of product generated in a chemical reaction.
- Actual yield — the measured amount of product from a real experiment.
- Theoretical yield — the calculated amount expected based on stoichiometry.
- Percentage yield — the ratio of actual yield to theoretical yield, shown as a percentage.
Action Items / Next Steps
- Practice calculating percentage yield using actual and theoretical yields from sample reactions.