NTA Abhyas JEE Main2020ChemistryThermodynamics (C)Practice
Calculate the heat produced (in kJ ) when 224 gm of CaO is completely converted to CaCO 3 by reaction with CO 2 at 27 o C in a container of fixed volume. Given : ΔH f o [ CaCO 3 ( s ) ] = − 1207 kJ/mol ; Δ H f o [ CaO ( s ) ] = − 635 kJ/mol Δ H f ∘ CO 2 , g = - 394 kJ/mol ; Use R = 8.3 K -1 mol -1
Options
- A-702 .04   kJ
- B721 .96   kJ
- C712   kJ
- D721   kJ
Correct answer
A. -702 .04   kJ
Step-by-step solution
CaO s + CO 2 g → CaCO 3 s Δ r H ∘ = Δ H f ∘ CaCO 3 - Δ H f ∘ CaO - Δ H f ∘ CO 2 = - 1 2 0 7 - - 6 3 5 - - 3 9 4 = - 178 kJ/mol ∴ Δ E r ∘ = Δ H r ∘ - Δ n g RT Δ E r ∘ = - 1 7 8 - - 1 × 8.3 × 3 0 0 1 0 0 0 = - 175.51 kJ n CaO = 2 2 4 5 6 = 4 ∴ q v = n · Δ r E = 4 × - 175.51 = - 702.04 kJ