Actual Yield
Definition and meaning of Actual Yield in chemistry.
Actual yield is the amount of product actually obtained from a chemical reaction under real-world conditions. It is typically less than the theoretical yield due to practical inefficiencies.
In more detail
Stoichiometry allows chemists to calculate the theoretical yield, the maximum amount of product that should form from given reactants. However, real reactions never achieve this ideal result. Side reactions, incomplete conversion of reactants, evaporation, product loss during transfer, and other practical factors reduce the final amount isolated. The actual yield is determined by directly measuring or weighing the isolated product. Comparing actual yield to theoretical yield, expressed as percent yield, reveals how efficiently a reaction proceeded.
Key facts
| Definition | The measured amount of product obtained from a chemical reaction |
|---|---|
| Contrasts with | Theoretical yield (predicted maximum from stoichiometry) |
| Efficiency metric | Percent yield = (actual ÷ theoretical) × 100% |
| Field | General Chemistry |
When 2.0 g of hydrogen gas reacts with excess oxygen to form water, stoichiometry predicts a theoretical yield of 18.0 g of H2O. If the actual isolation yields only 16.2 g of water, the actual yield is 16.2 g, giving a percent yield of 90%.
Frequently asked questions
Why is actual yield usually less than theoretical yield?
Real reactions experience side reactions, incomplete conversion of reactants, product loss during isolation, and other practical inefficiencies that prevent achieving the theoretical maximum.
How do you determine actual yield in the lab?
Actual yield is measured directly by isolating and weighing the solid product or measuring the volume of a liquid product after the reaction is complete and purification steps are finished.