A reaction has a theoretical yield of 25 g but only 20 g of product is obtained. The percentage yield is
- 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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