Colourful melting ice
THIS experiment examines how quickly ( or slowly) you can melt ice using salt and some watercolours.
It is a great fun learning activity for preschool- aged children to perform on a hot day.
Children will not only learn science, they will also practise their reasoning and motor skills. Make sure to ask questions and discuss what is happening to the ice as the experiment progresses.
What you need:
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• Cake tin Water Salt Watercolours or food colouring Paint brushes Small spoons Large baking dish ( optional)
Prepare ahead of time:
Freeze water in the cake tin. Remove the block of ice from the tin for the experiment. Fill an ice tray with water. Mix in different food colourings/ water colours to create a range
• of colours. Mix in some salt with each batch of coloured water. Place the block of ice on any surface or in a baking dish to contain the melting water.
What to do:
Pour some salt directly onto the block of ice; it will pop and crack. Why does this happen? Paint the block of ice with the watercolours. Does this speed up the melting? Continue painting and sprinkling salt onto the ice. Cracks will form, into which the watercolours will seep. Talk about what is happening and how it looks.
How it works:
Salt lowers the freezing point of ice – where water usually freezes at 0 C, it will now freeze at - 6 C ( with a 10% salt solution).
This means that as the salt dissolves into the water, it lowers its freezing and melting temperature, causing the ice to melt more quickly than usual.