My Year 9 science students always enjoy the famous pop test for hydrogen. If you make it competitive, looking for the loudest bang as the gas explodes, they enjoy it more. It serves to reinforce all their prejudices about mad scientists. The hydrogen explosions lead naturally to a class discussion about energy and fossil fuels. Ask questions about the safety of hydrocarbon fuels, such as petrol. If they had been invented last week, would they get safety clearance? Is hydrogen too dangerous to use?
Year 9 students will know about airship disasters such as the Hindenburg or the R101. Tell them that a high-velocity bullet fired through containers of petrol and hydrogen ignited only the former. Are they sure now about the safety issues? There is a lot of material on the internet about hydrogen as a fuel.
The topic of using hydrogen or other alternative fuels for cars is ideal to encourage key stage 3 pupils to use their imaginations. Ask them to describe or draw a car, to be ready for their 50th birthday when all the oil has run out.
One highly altruistic student designed a muscle-powered car, an updated version of that driven by Fred Flintstone. Most students opted for hydrogen power, emphasising the environmentally benign nature of the steam exhaust.
They were vague about the problem of refuelling or carrying sufficient hydrogen for a trip - Jbut auto engineers have yet to sort this out. The most improbable design came from a student who had been studying food labels, especially their energy content. The car was powered by chocolate cakes, an admirable idea if only the combustion problems can be solved.
Ray Oliver
Science teacher, St Albans Girls’ School, Hertfordshire
