Use the standard reaction enthalpies given below to determine ΔH°rxn for the following reaction: P4(g) + 10Cl2(g) → 4PCl5(s).

ΔH°rxn = ?
Given:
PCl5(s) → PCl3(g) + Cl2(g), ΔH°rxn = 157 kJ
P4(g) + 6Cl2(g) → 4PCl3(g), ΔH°rxn = -1207 kJ

a) -1318 kJ
b) -1038 kJ
c) +1318 kJ
d) +1038 kJ