A bomb calorimeter is calibrated by combusting of benzoic acid

CHEMISTRY · Single correct · A Level · Chemistry · Energetics · Energetics

Problem

A bomb calorimeter is calibrated by combusting

0.985\,\text{g}

of benzoic acid, which has an internal energy of combustion of

-26.38\,\text{kJ}\,\text{g}^{-1}

. The temperature of

950\,\text{g}

of water surrounding the bomb rises by

3.86\,^\circ\!\text{C}

. The same calorimeter is then used to burn

1.250\,\text{g}

of an unknown hydrocarbon, causing a temperature rise of

4.47\,^\circ\!\text{C}

. What is the specific internal energy of combustion of the unknown hydrocarbon (in kJ g

^{-1}

)? (a)

30.5\,\text{kJ}\,\text{g}^{-1}

(b)

24.1\,\text{kJ}\,\text{g}^{-1}

(c)

21.0\,\text{kJ}\,\text{g}^{-1}

(d)

18.6\,\text{kJ}\,\text{g}^{-1}