In this question, we have the following reaction:
CuO + H2 -> Cu + H2O, which is already balanced
We have to find the total amount of grams of copper produced from 5.60 Liters of H2 at STP (Standard Temperature and Pressure), and at these conditions, we have 1 mol = 22.4 Liters of volume, therefore we need to find the number of moles of H2 in 5.60 liters of volume:
22.4 L = 1 mol
5.60 L = x moles
x = 0.25 moles of H2 in 5.60 Liters
Now according to the molar ratio between Hydrogen gas and Cu being 1:1, which means we need 1 mol of H2 in order to produce 1 mol of Cu, if we have 0.25 moles of H2, we will also have 0.25 moles of Cu being produced
With the number of moles of Cu, 0.25 moles, and its molar mass, 63.55g/mol, we can find the final mass produced:
63.55g = 1 mol
x grams = 0.25 moles
x 15.9 grams of Copper is produced with 5.60 Liters of H2 gas