Let us assume that all gases are ideal. So we can use the formula:
PV = nRT
The reaction is:
CH4(g) + H2O(g) → CO(g) + 3H2(g)
First we determine what the limiting reactant is. This can be done by calculating for the number of moles (n) for each reactant.
For CH4:
nCH4 = (734 torr) (25.5 L) / (62.36367 L torr / mol K) (298.15 K)
nCH4 = 1 mol
For H2O:
nH2O = (704 torr) (22.6 L) / (62.36367 L torr / mol K) (398.15 K)
nH2O = 0.64 mol
Therefore H2O is the limiting reactant therefore the theoretical moles of H2 produced is:
nH2(theo) = 0.64 mol * (3 mol H2 / 1 mol H2O) = 1.92 mol
The actual moles of H2 is:
nH2(actual) = (750 torr) (26.4 L) / (62.36367 L torr / mol K) (273.15 K) = 1.16 mol
Therefore the yield is:
% yield = 1.16 / 1.92 * 100%
% yield = 60.42%