Stoichiometry and Yield Calculations in Chemistry

Theoretical Yield

• Definition: The theoretical yield is the maximum amount of product that can be produced from a given amount of reactants, assuming perfect conversion.
• Assumptions: Every molecule of reactant is flawlessly converted into products, representing the highest possible yield.

Actual Yield

• Definition: The actual yield is the amount of product actually obtained from a chemical reaction.
• Comparison: It is typically less than the theoretical yield due to various practical factors.

Percent Yield

• Definition: The ratio of the actual yield to the theoretical yield, expressed as a percentage.
• Formula: [ \text{Percent Yield} = \left( \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \right) \times 100 ]
• Purpose: Indicates the efficiency of a chemical reaction.

Example Calculation

• Reaction: Copper sulfate (CuSO4) and zinc metal (Zn) react to produce copper metal (Cu) and zinc sulfate (ZnSO4).
• Given: 1.2745 N2 G of copper metal.
• Theoretical Yield Calculation:
  • Convert mass of copper sulfate to moles.
  • Use stoichiometric ratio (1:1) to determine moles of copper metal expected.
  • Convert moles of copper to mass using molar mass.
  • Expected Theoretical Yield: 0.507 g of copper metal.
• Actual Yield: 0.392 g of copper metal was measured.
• Percent Yield Calculation:
  • [ \text{Percent Yield} = \left( \frac{0.392}{0.507} \right) \times 100 = 77.3% ]

Goal in Chemistry

• Aim for a percent yield as close to 100% as possible to maximize efficiency and reduce waste.
• A 77.3% yield indicates good efficiency but suggests potential improvements in the process.