Answer to Question #132121 in General Chemistry for Van Sung

Question

Why is it possible that the percent recovery could be greater than 100%?

Answer 1

It is impossible to get a recovery above $100\%$ as it violates the rule of law of conservation of mass.

But in certain cases it can be theoretically be above it:

1. Whenever there is an impurity is present in the product or reactant like the product being hygroscopic or adsorbing a particular compound or gas on its surface.
2. If the reaction taking place is in presence of air, some products may lead to disintegrate or react with oxygen present in air producing by products ultimately leading to increase in mass.
3. Inefficiency to remove the excess unreacted material properly. ( In such case the yield should be calculated on the basis of limiting reagent.