JEE MainChemistryThermodynamics (C)
A combustible gas is burnt in a bomb calorimeter that consists of a metal bomb surrounded by 800 g of water. The combustion of 0.05 mol of the gas causes the temperature of the system to increase by 5 K . If the specific heat capacity of water is 4.2 J g ⁻¹ K ⁻¹ and the heat capacity of the empty bomb is 840 J K ⁻¹ , the magnitude of the molar internal energy of combustion of the gas is ________ kJ mol ⁻¹ .
Correct answer
420
Step-by-step solution
Heat capacity of water = mass specific heat = 800 g 4.2 J g ⁻¹ K ⁻¹ = 3360 J K ⁻¹ Total heat capacity of the calorimeter system, C_ total = 3360 J K ⁻¹ + 840 J K ⁻¹ = 4200 J K ⁻¹ = 4.2 kJ K ⁻¹ Total heat released during combustion, q = C_ total T q = 4.2 kJ K ⁻¹ 5 K = 21 kJ Magnitude of molar internal energy of combustion = q n = 21 kJ 0.05 mol = 420 kJ mol ⁻¹ Answer: 420