Supercool

What you need

• Bottled or distilled water (not tap water)
• Freezer

Instructions

1. Put the bottle of water in to the freezer
2. Leave it alone for two to three hours. You’ll need to experiment with the exact timing as all freezers are different
3. Check regularly that the water is still liquid – but don’t move the bottle! While the water is still liquid, take the bottle out of the freezer carefully, then tap it suddenly on the edge of a table

Results and Explanation

The water will freeze! Water can stay liquid for several degrees below 0°C if there are no impurities or disturbances to start ice crystals forming. Tapping the bottle disturbs the ‘supercooled’ water and kicks off freezing.

These experiments have not been specifically safety tested for home use but we believe them to be safe if the instructions are followed. Adult supervision or direction is recommended as appropriate. All experiments are carried out at your own risk.