When 1.2 g of graphite is burnt in a constant volume bomb calorimeter, the temperature of the calorimeter increases by 1.5 K . If the heat capacity of the calorimeter is 20 kJ K ⁻¹ , the magnitude of the molar internal energy of combustion of graphite is ________ kJ mol ⁻¹ . (Given: Molar mass of carbon = 12 g mol ⁻¹ )

Step-by-step solution

Moles of graphite burnt = 1.2 12 = 0.1 mol Heat absorbed by the calorimeter, q = C T q = 20 kJ K ⁻¹ 1.5 K = 30 kJ Since the process occurs at constant volume, the heat released is equal to the magnitude of the change in internal energy. Magnitude of molar internal energy of combustion = q n = 30 kJ 0.1 mol = 300 kJ mol ⁻¹ Answer: 300