Resource 5: Teacher’s notes for investigating fuels
Teacher resource for planning or adapting to use with pupils
Prompt questions for the investigation and teacher’s notes about the investigation
Questions that you could use to help your students plan an investigation
- Which fuels will you use and where would you obtain the fuels?
- What type of containers would you use to boil the water?
- How much water would you put in the container?
- How will you time how long it takes for water in each container to boil using different fuels?
- How much fuel would you start with?
- How will you measure how much fuel is used?
- What would be the cost of a quarter of a kilogram (250 g) of each fuel?
- How will you make sure the energy from the fuel is not wasted?
- How will you decide which is the best fuel?
Questions you could use to see if your students understand the investigation
- How will you measure the heat produced?
- What measurements will you need to make?
- How will you make sure it is a fair test?
- Why is it important to ensure that it is a fair test?
- How can you make you experiment as accurate as possible?
- How will you record your results?
- How will you decide which fuel gives out the most energy?
- Which fuel do you think will be the best? Why?
You could also get your students to think about where the fuel comes from, is it sustainable and how much pollution is caused by burning that fuel on a large scale?
You need to test at least two fuels, e.g. wood and a liquid like ethanol or methylated spirit or kerosene. If you have spirit burners, put the liquid fuel in those and weigh them before and after the experiment to determine the mass of fuel burnt. If you don’t have spirit burners, use a teat pipette to measure a known volume of liquid fuel (a few millilitres) on to a piece of mineral wool. (You can use the density to calculate the mass). Break the wood into small pieces and burn a known mass on a bottle top or metal tin lid.
Measure 50 cm3 (or less if the containers are small) into a tin can. Measure the temperature of the water. Use the fuel to heat the water. Measure the temperature rise when a certain mass of fuel is burnt. If you don’t have a thermometer, measure the time taken for the water to boil.
The experiment can be made more accurate by preventing draughts, placing the tin can close to the fuel, etc. The aim is to calculate the temperature rise per gram of fuel burnt so you can make a direct comparison.
Wood, ethanol or methylated spirit, tin lids, tin cans, thermometers or stop watch, balance to weigh the fuel.
If you don’t have the equipment necessary to do the experiment, then you can burn fuels on a bottle top instead. For each one, get your students to suggest the features of a good fuel. While they burn, they could note down how easy it was to light, the amount of smoke produced, the amount of ash produced, whether it smells, the relative amount of heat given out (wave your hand above the burning fuel), the cost and any safety issues. This will still highlight the main issue: that there are lots of different fuels available and different ones are better for different jobs.