Design and make a device to lift as heavy an object as possible, at least 10 cm higher
As an energy source, the reaction between 1 level teaspoon of bicarbonate of soda (sodium hydrogencarbonate) and 3 level teaspoons of citric acid. Once lifted, the object must stay there.
This session could take around two hours and 30 minutes, or can be used for homework over a number of weeks.
- Eye protection
- Top-pan balance
- Standard masses (10 g & 100 g slotted masses, and 1 kg masses for the ambitious)
- Metre or half metre ruler
- Identical teaspoons (can be plastic)
- Sodium hydrogencarbonate (maximum amount = 3 level teaspoons)
- Citric acid (maximum amount = 9 level teaspoons)
Health, safety and technical notes
- Read our standard health and safety guidance here.
- Wear eye protection.
- Wear clothing protection if desired.
- Citric acid is an eye irritant, see CLEAPSS Hazcard HC036c
- This is an open-ended problem-solving activity, so the guidance given here is necessarily incomplete.
Perhaps guidance needed for younger age groups to say that water is needed for the reaction. The reaction might be used to do the lifting, or it could be used to start the lifting, eg to trigger movement of a counterbalance.
To increase the chemical content, the task could be extended by prior (or subsequent) experimentation, to select the best choice of gases/chemicals.
- Experiment | PDF, Size 17.08 kb
The resources were originally published in the book In Search of Solution P. Borrows, K. Davies and R. Lewin, Royal Society of Chemistry, 1990.
This experiment was based on an idea contributed by P. Borrows.