Frozen fun with sorbet
'Ice' to meet you
This activity helps girls learn about freezing points. As the fruit juice has less and less heat energy, it starts to freeze, making sorbet.
- Give each girl a large plastic zipper bag.
- Ask girls to put ½ cup water, ½ cup salt and 1 cup of ice in their bags.
- Give each girl a small plastic zipper bag half filled with fruit juice to put inside her large bag. Ensure that all the bags are completely closed. They should then shake their bags as hard as they can. After a while, the juice will begin to turn into sorbet. Keep checking to see when this happens.
- Girls can squeeze their sorbet into a bowl or eat it directly out of the small plastic bag.
The science behind it
When you add the salt to the ice it lowers the temperature at which the water becomes a solid inside the bag. This is called the freezing point. The ice begins to melt because it is no longer cold enough in the bag for it to stay frozen.
As the ice changes state from a solid to a liquid it uses heat energy from the fruit juice to melt. This means that the fruit juice has gradually less and less heat energy and becomes colder and colder until it starts to freeze. Voila! A slushy sorbet.
There are lots of hazards in the kitchen. Make sure you supervise girls carefully to ensure they don't come to harm.
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How many adults are needed?
Use this calculator to find out the ratio of girls to adults that is required for this activity