Percentage yield
How much product you really made compared with the most you could have made. Yield = actual mass / maximum mass x 100.
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Analogy
A baker plans 100 buns but ends up with 80 good ones. The yield is 80 percent.
Example
Maximum = 40 gActual = 30 gYield = 30 / 40 x 100= 75%
In practice
Yield is below 100 percent because of spills, side reactions and reactions that do not finish.
Practice
Flashcards
- What is the formula for percentage yield?Actual yield / maximum yield x 100.
- Why is the yield of a reaction often below 100 percent?Some product is lost, some reaction is reversible, and side reactions happen.
Questions people ask
Can percentage yield be over 100 percent?
In theory no. The theoretical maximum is the most you can ever make. If you calculate more than 100 percent in an experiment, the product is probably impure, still wet, or contains leftover reactant. It is a sign that something went wrong in the method.
Why do industries care about percentage yield?
A higher yield means more product from the same raw materials, which saves money and reduces waste. Companies adjust temperature, pressure and catalysts to push the yield up. In making ammonia, for example, conditions are chosen to balance yield, speed and cost.