A gas (Molar mass = 280 g mol ) was burnt in excess O in a constant volume calorimeter and during combustion the temperature of calorimeter increased from 298.0 K to 298.45 K. If the heat capacity of

Question

A gas (Molar mass = 280 g mol ) was burnt in excess O in a constant volume calorimeter and during combustion the temperature of calorimeter increased from 298.0 K to 298.45 K. If the heat capacity of calorimeter is 2.5 kJ K and enthalpy of combustion of gas is 9 kJ mol then amount of gas burnt is_______ g. (Nearest Integer) –1 2 –1 –1

Prashant Kotian · Accepted Answer

Correct answer: 35.00. # Solution **Step 1: Calculate heat released in the calorimeter** Use the formula: q = C × ΔT Where: - C = heat capacity = 2.5 kJ K⁻¹ - ΔT = 298.45 - 298.0 = 0.45 K q = 2.5 × 0.45 = 1.125 kJ **Step 2: Relate heat released to enthalpy of combustion** The heat released equals the enthalpy of combustion multiplied by moles of gas burnt: q = ΔH_combustion × n Where: - ΔH_combustion = -9 kJ mol⁻¹ (negative for combustion) - Using absolute value: 1.125 = 9 × n **Step 3: Calculate moles of gas burnt** n = 1.125 ÷ 9 = 0.125 mol **Step 4: Convert moles to mass** Use the formula: mass = n × M Where: - n = 0.125 mol - M = 280 g mol⁻¹ mass = 0.125 × 280 = 35 g Therefore, the answer is **35.00**.

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