Use the standard reaction enthalpies given below to determine _DrH° for the following reaction: 4SO₃(g) → 4S(s) + 6O₂(g) _DrH°= ?
Given:
SO₂(g) → S(s) + O₂(g) _DrH°= +296.8 kJ
2SO₂(g) + O₂(g) → 2SO₃(g) _DrH°= -197.8 kJ

Question

Quizplus · Accepted Answer

To find the reaction enthalpy for 4SO₃(g) → 4S(s) + 6O₂(g), reverse the second given reaction and multiply it by 2: 4SO₃(g) → 4SO₂(g) + 2O₂(g), ΔH° = 2 * 197.8 kJ = 395.6 kJ. Then, multiply the first reaction by 4: 4SO₂(g) → 4S(s) + 4O₂(g), ΔH° = 4 * 296.8 kJ = 1187.2 kJ. Add these enthalpies: 395.6 kJ + 1187.2 kJ = 1582.8 kJ, which rounds to 1583 kJ.

Use the Standard Reaction Enthalpies Given Below to Determine DrH°

Use the Standard Reaction Enthalpies Given Below to Determine _DrH°