Find the volume of hydrogen that is formed by the interaction of excess water vapor

Find the volume of hydrogen that is formed by the interaction of excess water vapor with 600 kg of hot coal, if the yield of the reaction product is 80%

Water react with carbon:
H2O + C = H2 + CO.
Carbon is consumed:
600,000 g: 12 g / mol = 50,000 mol. The same amount of hydrogen is released.
Let’s calculate the volume of hydrogen, not forgetting about the incomplete yield of the product:
22.4 l / mol * 5 * 10 ^ 4 mol * (80% / 100%) = 1.12 * 10 ^ 6 * 0.8 = 8.96 * 10 ^ 5 l.