Percentage yield calculations

Percentage yield is one of many deciding factors in determining whether or not a reaction is economically viable. It compares the experimental or actual mass of product made in a chemical reaction with the theoretical maximum mass possible – obviously, the higher the better!

Practice questions

1. Calculate the % yield of the production of iron from iron oxide if 0.30 tonnes of iron are produced from 5.0 tonnes of iron oxide.

Fe₂O₃   +  3CO    ⇾   2Fe   +   3CO₂

2. Calculate the % yield of copper oxide produced from the decomposition of  1.3 tonnes of copper carbonate, given that 0.45 tonnes of copper oxide are produced.

CuCO₃     ⇾     CuO   +    CO₂

Answers

1. 5.0 tonnes of Fe₂O₃ is 0.0313mol; 1:2 ratio; 0.0627 mol of Fe is 3.50 tonnes (which is how much we should have made);  % yield = 8.6%

2. 1.3 tonnes of CuCO₃ is 0.0105mol; 1:1 ratio; 0.0105 mol of CuO is 0.837 tonnes;  % yield = 53.8%