By Ashley K. Ezell • Updated Aug 30, 2022

In laboratory chemistry, the percent yield quantifies how effectively a reaction produces the desired product. It compares the actual mass of product obtained to the theoretical maximum predicted by stoichiometry, expressed as a percentage.

Sample Yields

Imagine immersing a 25‑gram copper sample in an aqueous silver nitrate solution—a classic displacement reaction that should generate silver metal. The stoichiometry of the reaction predicts a theoretical yield of 85 g of silver. After filtration and weighing, the recovered silver weighs only 82 g—this is the actual yield.

Sample Calculation

Percent yield is calculated with the formula:
Percent yield = (Actual yield ÷ Theoretical yield) × 100

Applying the numbers from our example: 82 g ÷ 85 g × 100 = 96 % This 96 % figure indicates that the reaction proceeded with high efficiency; values closer to 100 % reflect fewer side reactions, better purification, and minimal product loss.

Why Percent Yield Matters

Monitoring percent yield helps chemists:

• Identify inefficiencies or impurities in a procedure.
• Optimize reaction conditions to maximize product recovery.
• Benchmark reproducibility across different runs or laboratories.

References

• Glencoe Chemistry: Matter and Change; Laurel Dingrando, et al.