How much energy comes from burning fuels?
In this experiment you are going to find out how much energy comes from one burning fuel and
compare this with other fuels. You should work in pairs.
Equipment
Spirit burner containing an alcohol
Splints
Calorimeter
Heat shield
100-200 cm3 water
50 cm3 or 100 cm3 measuring cylinder or 50 cm3 pipette
Protective mat
Eye protection
Thermometer reading 0-110 °C in 0.1 °C increments
Access to a balance
Retort stand, boss and clamp.
What you do
Put 100 cm3 of water in the calorimeter.
Record the temperature of the water.
Clamp the calorimeter in position about 10 cm above the protective mat.
Find the mass of a spirit burner containing an alcohol.
Place the burner under the calorimeter and light the wick.
Place the heat shield around the apparatus.
Stir the water with the thermometer.
Stop heating when the temperature has risen by 20 °C.
Replace the cap on the burner.
Reweigh the burner as soon as possible.
Keep noting the temperature – record the highest value reached.
If you can, repeat the experiment with other alcohols.
Try to keep all the factors the same.
Working out the amount of energy released
The energy change that happens when a fuel burns is called the enthalpy change of combustion.
You are going to calculate the enthalpy change of combustion for the alcohols you burned.
1. You need to know:
the mass of alcohol burned
the temperature rise of the water
the mass of the water (if you used 100 cm3 this will be 100 g).
2. Find out the amount of energy transferred to the water.
energy (J) = mass of water x specific heat capacity of water x temperature rise
energy (J) = 100 x 4.2 x temperature rise you measured
