IMAT 2011 Q63 [Yield of Copper]

8.0g of copper oxide is reduced to 5.6g of copper using hydrogen gas.

[relative atomic mass: Cu=64, O=16]
{CuO + H_2 → Cu + H_2O}

What is the yield of copper as a percentage of the theoretical maximum?

A. 14.3%
B. 43.9%
C. 56.0%
D. 70.0%
E. 87.5%

This is a basic mole calculation that usually appears on the IMAT, to practice more of this kind of question you can learn the first chapter of Pearson’s chemistry as was suggested in the IMAT Study Planner of 2022 we have on the main website.

The first step is to convert everything into moles.

In our case, with the information provided, we can calculate the moles of both the reactant and the product.

We can see that under ideal conditions we would have 8 / 80 = 0.1 moles of copper. But in reality, we ended up with just 5.6 / 64 = 0.0875 moles of copper.

Using the percentage yield equation we have: actual yield / theoretical yield *100% = 87.5%. Thus the correct answer is E.