Calculate Δ H for C(s) + H₂O(g) → CO(g) + H₂(g) given: C(s) + O₂(g) → CO₂(g), Δ H = -393.5 kJ/mol; CO(g) + (1/2)O₂(g) →
Reverse second: Δ H = 283 kJ. Add third: Δ H = 241.8 kJ. Subtract first: Δ H = 283 + 241.8 - 393.5 = 131.3 kJ/mol.
Ref: NCERT Class 11 Chemistry > Chapter 5: Thermodynamics > Topic: Third Law of Thermodynamics and Applications