2.4 g coal is burnt in a bomb calorimeter in excess of oxygen at 298 K and 1 atm pressure. The temperature of the calorimeter rises from 298 K to 300 K. The enthalpy change during the combustion of co

Question

2.4 g coal is burnt in a bomb calorimeter in excess of oxygen at 298 K and 1 atm pressure. The temperature of the calorimeter rises from 298 K to 300 K. The enthalpy change during the combustion of coal is –x kJ mol . The value of x is ______. (Nearest Integer) (Given: Heat capacity of bomb calorimeter 20.0 kJ K . Assume coal to be pure carbon) –1 –1

Prashant Kotian · Accepted Answer

Correct answer: 200. **Step 1: Calculate heat absorbed by the calorimeter** Using q = C × ΔT where C = heat capacity = 20.0 kJ K⁻¹ and ΔT = 300 K – 298 K = 2 K q = 20.0 × 2 = 40 kJ **Step 2: Determine moles of carbon burned** Molar mass of C = 12 g/mol Moles of coal = 2.4 g ÷ 12 g/mol = 0.2 mol **Step 3: Calculate enthalpy change per mole** The heat released during combustion = 40 kJ (for 0.2 mol of C) For 1 mole: ΔH = 40 kJ ÷ 0.2 mol = 200 kJ/mol **Step 4: Apply sign convention** Since combustion is exothermic (releases heat), ΔH is negative. ΔH = –200 kJ/mol **Step 5: Identify x value** Given ΔH = –x kJ/mol, where x = 200 Therefore, the answer is **200**.

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