When one mole of C 6 H 5 COOH ( s ) is burnt completely in sufficient oxygen in closed rigid vessel then it liberate 2 kJ heat at 300 K . Find magnitude of enthalpy change of reaction (in Joules)

Question

When one mole of C 6 ​ H 5 ​ COOH ( s ) is burnt completely in sufficient oxygen in closed rigid vessel then it liberate 2 kJ heat at 300 K . Find magnitude of enthalpy change of reaction (in Joules) at 300 K when 12.2 gm C 6 ​ H 5 ​ COOH ( s ) is reacted with 33.6 L oxygen (at 1 atm & 273 K ) ( R = 8 J / mol − K ).

TestHub · Accepted Answer

For a rigid vessel: q v ​ = Δ U = − 2000 J m o l − 1 Reaction: C 6 ​ H 5 ​ COO H + 2 15 ​ O 2 ​ → 7 C O 2 ​ + 3 H 2 ​ O For 12.2 g benzoic acid: n = 122 12.2 ​ = 0.1 m o l Δ n g ​ = 7 − 7.5 = − 0.5 Δ H = Δ U + Δ n g ​ RT = − 200 + ( − 0.5 ) ( 8 ) ( 300 ) × 0.1 = − 320 J Magnitude: 320 J

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