Use the standard reaction enthalpies given below to determine ΔH°_rxn for the following reaction: P₄(g) + 10 Cl₂(g) → 4 PCl₅(s) ΔH°_rxn= ?
Given:
PCl₅(s) → PCl₃(g) + Cl₂(g) ΔH°_rxn= +157 kJ
P₄(g) + 6 Cl₂(g) → 4 PCl₃(g) ΔH°_rxn = -1207 kJ

Question

Quizplus · Accepted Answer

To find ΔH°_rxn for the given reaction, use Hess's Law. Reverse the first reaction and multiply by 4: 4(PCl₃(g) + Cl₂(g) → PCl₅(s)) ΔH° = -4(157 kJ). Add this to the second reaction: P₄(g) + 6 Cl₂(g) → 4 PCl₃(g) ΔH° = -1207 kJ. The total ΔH°_rxn = -4(157 kJ) - 1207 kJ = -1835 kJ.

Use the Standard Reaction Enthalpies Given Below to Determine ΔH°rxn

Use the Standard Reaction Enthalpies Given Below to Determine ΔH°_rxn