The United States gets 95% of its hydrogen gas by "steam reforming" methane, CH4(g).
Another option is the “partial oxidation” of hydrocarbons to make carbon monoxide and hydrogen gas. For octane, that reaction would be
C8H18(l) + 4O2(g) → 8CO(g) + 9H2(g)
We know ΔH° for the combustion of octane
C8H18(l) + 25/2 O2(g) → 8CO2(g) + 9H2O(l) ΔH° = -5500 kJ/mol
Assume the arbitrary values below for the combustion reactions of carbon monoxide and hydrogen:
CO(g) + 1/2 O2(g) → CO2(g) ΔH° = “-290 kJ/mol”
H2(g) + 1 /2O2(g) → H2O(l) ΔH° = “-285 kJ/mol”
A. Do you expect the magnitude of ΔH° for the partial oxidation of octane, to be greater or less than the magnitude of ΔH° for the combustion of octane? Explain.
B. Now, determine ΔH° for the partial oxidation of octane with those assigned values. Choose from the choices below
C. Do you think the hydrogen produced provides more or less energy than you would get from the combustion of octane? Explain.
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