A rocket fuel would be useless if its oxidation were not spontaneous. Although rockets operate under conditions that are far from standard, an initial estimation of the potential of a rocket fuel might assess whether its oxidation at the high temperatures reached in a rocket is spontaneous. A chemist exploring potential fuels for use in space considered using vaporized aluminum chloride in a reaction for which the skeletal equation is

Balance this equation. Th en use the following data (which are for 2000 K) to decide whether the fuel is worth further investigation: ΔG_f° (AlCl₃, g) = –467 kJ · mol^–1, ΔG_f° (Al₂O₃, s) = –1034 kJ · mol^–1, ΔG_f° (ClO, g) = +75 kJ · mol^–1.

AlCl3 (g) + O(g) AlO3 (s) + ClO(g)