Chemistry · Quantitative chemistry. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
The theoretical yield is the maximum mass of product that the balanced equation says can be made. The mass actually obtained is usually less. Percentage yield compares the two.
The yield is below 100% because the reaction may be reversible and not go to completion, some product is lost when it is separated from the mixture, or some reactants react in other ways.
Atom economy is different. It is worked out from the equation only and shows what percentage of the mass of the reactants ends up in the product you want. A high atom economy means less waste, so the process is more sustainable and usually cheaper.
Students mix up the two ideas. Percentage yield uses the mass measured in the experiment; atom economy uses only the Mr values in the balanced equation.
Answer: Percentage yield = 75%
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