The enthalpy of combustion, ΔH, for benzoic acid, C6H5COOH, is -3226 kJ/mol. When a sample of...

The enthalpy of combustion, ΔH, for benzoic acid, C₆H₅COOH, is -3226 kJ/mol. When a sample of benzoic acid was burned in a calorimeter (at constant pressure), the temperature of the calorimeter and contents rose from 23.20°C to 28.40°C. The heat capacity of the calorimeter and contents was 12.41 kJ/ °C. What mass of benzoic acid was burned?

Expert Solution

heat supplied, Q = C*(Tf-Ti)
=12.41 * (28.4-23.2)
=64.532 KJ

Number of moles of benzoic acid burnt = 64.532 / 3226 = 0.02 mol
Molar mass of benzoic acid = 122 g/mol
Mass of benzoic acid = molar mass * number of moles
= 122 * 0.02
= 2.44 g
Answer: 2.44 g

queen_honey_blossom answered 2 days ago

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