Consider the atomization of Br 2 (g) according to the reaction : Br 2 g ⇌ 2 Br g Given antiloge(-7.02)=9x10-4 If the heat of atomization of bromine gas is 82 KJ/mol ; standard molar entropies of Br(g) and Br 2 (g) are 175 and 245.4 JK -1 respectively, calculate degree of dissociation when the total pressure is 40 atm at 500 K. (assume α <<1 in your calculation)

Step-by-step solution

For Br 2 g ⇌ 2 Br g Δ S reac ∘ = 2 × 1 7 5 - 2 4 4 · 4 = 105.6 J K - 1 Δ H reac ∘ = 8 2 KJ m - 1 Δ G reac ∘ = Δ H reac ∘ - T Δ S ∘ = 8 2 0 0 0 - 5 0 0 × 105.6 = 2 9 · 2 × 1 0 3 J = - RT ln K P ln K P = - 2 9 7 0 0 8 · 3 1 4 × 5 0 0 = - 7.02 ∴ K P = 9 × 10 − 4 K P = 4 α 2 P 1 − α 2 as α < < 1 ∴ 1 − α 2 = 1 ∴ K P = 4 × α 2 P ∵ P = 40 ∴ 9 × 10 − 4 = 4 ⋅ α 2 ⋅ 40 ∴ α 2 = 9 160 × 10 − 4 = 9 16 × 10 − 5 = 2.37 × 10 − 3