Reactions rarely give as much product as the balanced equation predicts. The theoretical yield is the maximum amount you could make from the limiting reagent; the actual yield is what you really get. Their ratio, as a percentage, is the percent yield.
Use grams for both, or moles for both. A percent yield over 100% usually means the product is still wet or impure.
| Actual yield | 8.5 g |
| Theoretical yield | 10 g |
| Percent yield | 85% |
| Amount not recovered (same unit) | 1.5 |
Getting 8.5 g out of a possible 10 g is a 85% yield.
Try this example →| Actual yield | 5.4 g |
| Theoretical yield | 5 g |
| Percent yield | 108% |
| Amount not recovered (same unit) | 0 |
A yield of 108% means the product is probably not fully dry or pure.
Try this example →Percent yield = (actual yield ÷ theoretical yield) × 100.
Not really. A result over 100% usually means the product is wet or contains impurities.
The maximum mass of product predicted by the balanced equation from the amount of limiting reagent.
It depends on the reaction; in school labs 70–90% is often considered good.