\(m_{Fe_2O_3}=80\%.50=40\left(g\right)\Rightarrow n_{Fe_2O_3}=0,25\left(mol\right)\\ m_{CuO}=50-40=10\left(g\right)\Rightarrow n_{CuO}=0,125\left(mol\right)\\Fe_2O_3+3H_2-^{t^o}\rightarrow 2Fe+3H_2O\\ CuO+H_2-^{t^o}\rightarrow Cu+H_2O\\ \Sigma n_{H_2}=0,25.3+0,125=0,875\left(mol\right)\\ \Rightarrow V_{H_2}=0,875.22,4=19,6\left(l\right)\)