Percent Yield Calculator
A percent yield calculator determines how efficiently a chemical reaction produces a desired product by comparing the actual yield with the theoretical yield. It is commonly used in chemistry, laboratory experiments, and reaction analysis.
What Is Percent Yield?
Percent yield shows how much product was actually obtained compared with the maximum amount that could theoretically be produced.
Percent Yield Formula
The formula is:
Percent Yield = (Actual Yield Γ· Theoretical Yield) Γ 100
The actual yield is the amount of product obtained from the experiment, while the theoretical yield is the maximum amount predicted by stoichiometric calculations.
How to Calculate Percent Yield
Suppose a reaction has a theoretical yield of 25 g, but the experiment produces 20 g of product.
Substitute the values:
Percent Yield = (20 Γ· 25) Γ 100
Percent Yield = 80%
Therefore, the reaction has a percent yield of 80%.
Actual Yield vs. Theoretical Yield
| Term | Meaning |
|---|---|
| Actual yield | The amount of product actually obtained from the experiment. |
| Theoretical yield | The maximum amount of product predicted by stoichiometry. |
| Percent yield | The actual yield expressed as a percentage of the theoretical yield. |
Why Is Percent Yield Less Than 100%?
In many real experiments, the percent yield is below 100% because some product may be lost during transfers, filtration, purification, or other laboratory steps. Reactions may also be incomplete or produce unwanted side products.
A result above 100% can indicate impurities, leftover solvent or moisture, measurement errors, or an incorrect theoretical-yield calculation.
Percent Yield Example
If the theoretical yield is 50 g and the actual yield is 42 g:
Percent Yield = (42 Γ· 50) Γ 100 = 84%
The experiment therefore achieved an 84% yield.
Using Percent Yield in Stoichiometry
Percent yield is normally calculated after determining the theoretical yield from a balanced chemical equation. Theoretical yield depends on the available reactants and the stoichiometric ratio of the reaction.
If the actual yield and percent yield are known, the theoretical yield can also be found by rearranging the formula:
Theoretical Yield = Actual Yield Γ· (Percent Yield Γ· 100)
Common Mistakes to Avoid
Use the same units for actual and theoretical yield before performing the calculation. For example, do not divide a yield in grams by a theoretical yield in kilograms without converting the units first.
Also make sure the theoretical yield is based on the correctly balanced chemical equation and the limiting reactant.
Quick Summary
Percent yield compares the actual amount of product obtained with the theoretical maximum. Use Percent Yield = (Actual Yield Γ· Theoretical Yield) Γ 100. A higher percentage generally indicates that the experimental process produced an amount closer to the theoretical prediction.