JEE Main · 2022 · 26 Jul 2022 · Shift 1 · Chemical Thermodynamics

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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^{- 1}

. The value of x is ______. (Nearest Integer)
(Given : Heat capacity of bomb calorimeter 20.0 kJ

K^{- 1}

. Assume coal to be pure carbon)

Answer: 200

Solution

Heat released Q = C × ΔT = 20 kJ/K × (300 - 298) K = 40 kJ. This is for 2.4 g of carbon. Moles of carbon = 2.4/12 = 0.2 mol. Heat per mole = 40/0.2 = 200 kJ/mol. Therefore, x = 200.

JEE Main · 2022 · 26 Jul 2022 · Shift 1 · Integer answer

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