Standard enthalpies of formation (kJ mol⁻¹) at 298 K:
H₂(g) 0 CH₄(g) −74.8 C₂H₄(g) +52.3 CO₂(g) −393.5 H₂O(l) −285.8 O₂(g) 0
Consider the complete combustion of the following fuels.
Fuel I: H₂(g) H₂ + ½ O₂ → H₂O(l)
Fuel II: CH₄(g) CH₄ + 2 O₂ → CO₂ + 2 H₂O(l)
Fuel III: C₂H₄(g) C₂H₄ + 3 O₂ → 2 CO₂ + 2 H₂O(l)
Which fuel releases the greatest amount of energy per gram of fuel burned under standard conditions?
a) Fuel II
b) Fuel I
c) Fuel III
d) It cannot be determined from the information provided