The percentage yield shows how much product is obtained compared to the maximum possible mass. The atom economy of a reaction gives the percentage of atoms in reactants that form a desired product.
An actual yield is the mass of a product actually obtained from the reaction. It is usually less than the theoretical yield. The reasons for this include:
The percentage yield is calculated using this equation:
\[percentage\ yield\ =\ \frac{actual\ yield}{theoretical\ yield}\ \times\ 100\]
Worked example
Copper oxide reacts with sulfuric acid to make copper sulfate and water. In an experiment, 1.6 g of dry copper sulfate crystals are made. If the theoretical yield is 2.0 g, calculate the percentage yield of copper sulfate.
actual yield = 1.6 g
\[percentage\ yield\ =\ \frac{1.6}{2.0}\ \times\ 100\]
percentage yield = 80%
In an experiment, the theoretical yield is 3.2 g but the actual yield is only 2.4 g. Calculate the percentage yield.
\[percentage\ yield\ =\ \frac{2.4}{3.2}\ \times\ 100\]
percentage yield = 75%