Percent Yield: worked example
| Actual yield | 8.2 |
|---|---|
| Theoretical yield | 10 |
| Percent yield | 82.0% |
| Amount lost | 1.8 |
Common error: Comparing an actual mass with a theoretical number of moles. Both must be in the same unit, and the theoretical yield comes from the limiting reagent.
Percent Yield: formula
The theoretical yield depends on correct stoichiometry and identification of the limiting reactant. Impure or wet products distort the result. Reversible reactions may never reach 100%.
A high percent yield does not show the purity of the product.
Enter the actual yield, the amount of product you obtained, and the theoretical yield, the maximum amount predicted by stoichiometry from the limiting reactant. Use the same units for both, usually grams or moles. The theoretical yield comes from the balanced equation and the amount of the limiting reactant.
Weigh the product dry and pure, since impurities and solvent inflate the actual yield.
Percent Yield: changing Actual yield
| Actual yield | Percent yield | Amount lost |
|---|---|---|
| 6.6 | 66.0% | 3.4 |
| 7.4 | 74.0% | 2.6 |
| 8.2 (example) | 82.0% | 1.8 |
| 9 | 90.0% | 1 |
| 9.8 | 98.0% | 0.2 |
Percent Yield: compare input ranges
| Input | Tested from | To | Percent yield: low input | Percent yield: high input | Swing |
|---|---|---|---|---|---|
| Theoretical yield | 9 | 11 | 91.1% | 74.5% | 16.6% (20%) |
| Actual yield | 7.4 | 9 | 74.0% | 90.0% | 16.0% (20%) |
Percent Yield: individual input comparisons
| Input | Value | Percent yield | Amount lost |
|---|---|---|---|
| Actual yield | 6.6 | 66.0% | 3.4 |
| 7.4 | 74.0% | 2.6 | |
| 8.2 | 82.0% | 1.8 | |
| 9 | 90.0% | 1 | |
| 9.8 | 98.0% | 0.2 | |
| Theoretical yield | 8 | 102.5% | -0.2 |
| 9 | 91.1% | 0.8 | |
| 10 | 82.0% | 1.8 | |
| 11 | 74.5% | 2.8 | |
| 12 | 68.3% | 3.8 |
Percent Yield: combined input changes
| Actual yield / Theoretical yield | 8 | 10 | 12 |
|---|---|---|---|
| 6.6 | 82.5% | 66.0% | 55.0% |
| 7.4 | 92.5% | 74.0% | 61.7% |
| 8.2 | 102.5% | 82.0% | 68.3% |
| 9 | 112.5% | 90.0% | 75.0% |
| 9.8 | 122.5% | 98.0% | 81.7% |
Percent Yield: which assumptions move the result?
Percent Yield: values and definitions
| Quantity and definition | Value used |
|---|---|
| Actual yield | 8.2 |
| Theoretical yield — In the same unit as the actual yield. | 10 |
| Percent yield | 82.0% |
| Amount lost | 1.8 |
Percent Yield: half and double Theoretical yield
| Theoretical yield | Percent yield |
|---|---|
| 5 | 164.0% |
| 10 | 82.0% |
| 20 | 41.0% |
Science & Electronics calculators: PPM Concentration Calculator, Ohm's Law Calculator, Density Calculator, Molarity Calculator, Voltage Drop Calculator, Dilution Calculator.
Percent yield compares what a reaction made with the most it could make on paper. An actual 8.2 grams out of a theoretical 10.0 is 82 percent, and the missing 1.8 grams went to side reactions, transfers and losses in purification. Yields near 100 percent are rare in work.
A yield above 100 percent is a warning that the product is wet or impure.
An assumed 10 grams of wet product containing 2 grams of retained solvent contains only 8 grams of product. Against a 12-gram theoretical yield, the uncorrected mass gives 83.33%, while the dry-product mass gives 66.67%. The solvent is not reaction product.
Impurities or retained liquid change the numerator without increasing the target substance obtained.
Compute concentrations on the molarity and ppm calculators, dilutions on the dilution page, and percent error on the percent error calculator. The density, pH and half-life pages cover other lab quantities, and the percentage and proportion calculators help with ratios.
What is percent yield?
The actual amount of product you obtained divided by the theoretical maximum the reaction could give, expressed as a percentage.
Why is percent yield usually below 100%?
Reactions may be incomplete, side products form and some product is lost during separation and purification.
What does a yield over 100% mean?
Usually an error, such as wet or impure product, since a reaction cannot create more product than the reactants allow.