Challenge pupils to balance sinking against floating, with a toy submarine concept
Design and make a device (with final dimensions NOT exceeding 15 cm × 15 cm × 15 cm) which will sink in water, and then after a reasonable length of time, rise to the surface.
This session could take around two hours and 30 minutes, or can be used for homework over a number of weeks.
- A selection of junk materials
- Plastic beakers, 100 cm3
- Stop clocks
- Masses, 10g
- Rubber bands
- Rubber tubing (1 metre)
- Sticky tape or masking tape
- Identical teaspoons (plastic can be used)
- Ruler, 30 cm
- Plastic buckets for ‘test runs’
For students who have studied neutralisation reactions:
- Hydrochloric acid, 0.5 mol dm-3
- Marble chips
- Tartaric acid
Selection of chemicals:
- ‘Alka Seltzer’ tablets
- Andrews’ liver salts, or a mixture of solid sodium hydrogencarbonate/citric acid (1 teaspoon of sodium hydrogencarbonate to 3 teaspoons of citric acid).
- Access to water.
Health, safety and technical notes
- Read our standard health and safety guidance here.
- Wear eye and/or clothing protection if desired.
- This is an open-ended problem-solving activity, so the guidance given here is necessarily incomplete.
- Citric acid is an eye irritant, wear eye protection, see CLEAPSS Hazcard HC036c
Generating a gas which causes a container to become buoyant; weighting a container with soluble material and allowing water to dissolve it so that the container then rises to the surface. (The sinking or floating/rising aspects could be investigated separately.)
Increasing the complexity of the behaviour required in terms of time limits and depth limits. Extend to actual lifting of a submerged object.
The ups and downs of chemistryExperiment | PDF, Size 17.46 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 Sussex SATRO.
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