A reaction has a theoretical yield of 25 g but only 20 g of product is obtained. The percentage yield is
Correct answer: B. 80 per cent
- A. 125 per cent
- B. 80 per cent
- C. 5 per cent
- D. 20 per cent
Explanation
Percentage yield is actual divided by theoretical multiplied by 100, so 20 divided by 25 multiplied by 100 gives 80 per cent. Dividing the wrong way round gives 125 per cent, which should be recognised as impossible because a reaction cannot produce more than the equation allows. A figure above 100 per cent in real work means the product is still wet or impure.
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About Theoretical and Percentage Yield
Theoretical yield is the maximum product predicted from a balanced equation and the amount of limiting reactant. Work includes identifying the limiting reagent, comparing theoretical and actual yield, and calculating percentage yield using stoichiometric mole relationships.
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