Question -
Answer -
Enthalpy change for a reaction (ΔH) is given by theexpression,
ΔH = ΔU + ΔngRT
Where,
ΔU = change in internalenergy
Δng = change in numberof moles
For the given reaction,
Δng = ∑ng (products) – ∑ng (reactants)
= (2 – 1.5) moles
Δng = 0.5 moles
And,
ΔU = –742.7 kJ mol–1
T = 298 K
R = 8.314 × 10–3 kJ mol–1 K–1
Substituting the values in the expression ofΔH:
ΔH = (–742.7 kJ mol–1) + (0.5 mol) (298 K)(8.314 × 10–3 kJ mol–1 K–1)
= –742.7 + 1.2
ΔH = –741.5 kJ mol–1