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Description

Science presenter Jon Chase demonstrates that a large piece of expanded polystyrene will dissolve in a very small volume of propanone. He defines the terms solute, solvent and solution.

By dissolving sugar into cups of tea, Jon demonstrates that solutions can become saturated. When one of the cups is then cooled down, some of the sugar recrystallises, demonstrating that the solubility of most solids increases with temperature. But most gases become less soluble at higher temperature, and Jon demonstrates how to use this principle to make clear ice cubes.
This clip is from:
First broadcast:
11 May 2012

Classroom Ideas

Following the clip, students could investigate the solubility of different solutes, with some groups changing the solute, some groups changing the solvent and other groups changing the temperature. Note that not all solutes increase in solubility as the temperature rises. For example, try sodium sulfate. Students could prepare saturated solutions and then grow crystals in them as they cool down. Relate the topic to the solubility of fertilisers.