Question

Substance	ΔHf°gas (kJ/mol)	ΔHf°liquid (kJ/mol)	ΔHc° (calculated) (kJ/mol)	ΔHc° (from NIST) (kJ/mol)
Carbon dioxide	-393.52
water	-241.83 ± .040	-285.83 ± .040
methane	-74.87		-890.31	-890.35
ethane	-83.8 ± 0.3		-1560.73	-1560.7 ± 0.3
propane	-104.7 ± 0.50		-2219.18	-2219.2 ± 0.46
2,2,4-trimethylpentane	-224.1 ± 1.3	-259.3 ± 1.3	-5461.33	(from liquid) -5461.3 ± 1.3

Which of the potential fuels (hydrogen, methane, ethane, propane, 2,2,4-trimethylpentane) is the most efficient? Explain your answer with the calculated enthalpies of combustion.

Answer 1