Percent Yield Notes

New Vocabulary

• Theoretical yield: Maximum product from reactant amount.
• Actual yield: Product obtained in an experiment.
• Percent yield: Ratio of actual to theoretical yield, expressed as a percentage.

How Much Product?

• Reactions rarely produce the predicted product amount due to:
  • Adherence to container surfaces or evaporation.
  • Competing reactions.
  • Loss during purification or on filter paper.

Theoretical vs. Actual Yield

• Theoretical yield: Maximum product from reactant amount.
• Actual yield: Product obtained experimentally.
• Percent yield: $\frac{Actual Yield}{Theoretical Yield} × 100$%

Percent Yield Example

• Reaction: $2AgNO<em>3(aq) + K</em>2CrO<em>4(aq) \rightarrow Ag</em>2CrO<em>4(s) + 2KNO</em>3(aq)$
• Problem: 0.500 g $AgNO<em>3$ yields 0.455 g $Ag</em>2CrO_4$.
• Convert grams of $AgNO_3$ to moles: $0.500 g \times \frac{1 mol}{169.9 g} = 2.94 × 10^{-3} mol$
• Convert moles of $AgNO<em>3$ to moles of $Ag</em>2CrO<em>4$: $2.94 × 10^{-3} mol \times \frac{1 mol Ag</em>2CrO<em>4}{2 mol AgNO</em>3} = 1.47 × 10^{-3} mol$
• Calculate theoretical yield of $Ag<em>2CrO</em>4$: $1.47 × 10^{-3} mol \times \frac{331.7 g}{1 mol} = 0.488 g$
• Calculate percent yield: $\frac{0.455 g}{0.488 g} = 93.2$%

Marketplace Importance

• Percent yield impacts cost-effectiveness in industrial processes.
• Industry aims for high yield, speed, and low cost.