Question

The bomb calorimeter is tested with a fuel of unknown energy content, and the following observations were recorded:

Mass of fuel burnt = 1.25g
Mass of water in the calorimeter = 2.75 kg
Water temperature before firing = 18.5 degree Celcius.
Water temperarure after firing = 21.8 degree Celcius.

Determine the energy content of the fuel.

Answer 1

Let the specific heat capacity of water = 4200 J / kg °C

Mass of water = 2.75 kg.

Mass of fuel = 1.25g = 1.25/1000 kg = 0.00125 kg.


Heat from Energy content of fuel = Heat gained by water.

Mass of fuel * Energy content of fuel = mcΔθ

0.00125 kg * Energy content of fuel = 2.75 * 4200 * (21.8 - 18.5)

0.00125 kg * Energy Content of fuel = 38.115 J

Energy content of fuel = 38.115 J / 0.00125 kg

Energy content of fuel = 30 492 J/kg = 30.492 kJ/kg