How much hydrogen is needed to reduce copper from 40 g of copper oxide (2) containing 25% impurities?

1. Let’s compose a chemical equation, not forgetting to put down the coefficients:

CuO + H2 = Cu + H2O.

2. Let’s find the mass fraction of copper oxide:

ω (CuO) = 100% – 25% = 75% (0.75).

3. Find the mass of copper oxide:

m (CuO) = 40g * 0.75 = 30g.

4. Find the amount of copper oxide substance:

n (CuO) = 30g / 80 g / mol = 0.375 mol.

5. According to the chemical equation we see:

n (CuO) = n (H2).

6. Find the volume of hydrogen:

V (H2) = n * Vm = 0.375 * 22.4 = 8.4 liters.

Answer: V (H2) = 8.4 liters.