Question

A sample of octane (C8H18) that has a mass of 0.750 g is burned in a bomb calorimeter. As a result, the temperature of the calorimeter increases from 21.0°C to 41.0°C. The specific heat of the calorimeter is 1.50 J/(g • °C), and its mass is 1.00 kg. How much heat is released during the combustion of this sample?
Use q equals m C subscript p Delta T..
22.5 kJ
30.0 kJ
31.5 kJ
61.5 kJ

Answer 1

q = m Cp ΔT = (1000 g)(1.50 J/g°C)(41.0 − 21.0 °C) = 1000·1.50·20.0 = 30,000 J = 30.0 kJ.

So 30.0 kJ of heat is released (qcombustion = −30.0 kJ). Answer: 30.0 kJ.