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.
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