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Description

Make slime that changes colour in different temperatures

Resources

Per person -

1 cup of PVA Glue
1 teaspoon Bicarbonate of Soda
1-2 teaspoons of thermochromic powder
1 tablespoon contact lens solution (containing boric acid)
Bowl, spoon

Optional - complementary coloured food colouring
Cling film/pot or similar to wrap the slime in at the end

Instructions

Instructions for slime recipe
Tip 1 cup of the PVA glue into a clean bowl.
Then add 1 teaspoon of bicarbonate of soda (baking soda.)
Mix them together.
Add the thermochromic powder.
Next add 1 tablespoon of contact lens solution.
Mix with a spoon until it starts to become stringy, coming away from the edges of the bowl (almost like when you’re cooking eggs.)

Change the experiment
Add a drop of complementary food colour to the mixture and see what happens. (g.g., if the powder is a green colour, add yellow food colouring)

How it works:

What makes slime so thick and stretchy?
The glue has long flexible molecules in it called polymers. These polymer molecules slide past each other as a liquid.

Borax in water forms an ion called the borate ion. When the borax solution is added to the glue solution, the borate ions help link the long polymer molecules to each other so they cannot move and flow as easily.

When enough polymer molecules get hooked together in the right way, the glue solution changes from being very liquidy to a rubbery kind of stuff that we call slime!

What makes the colour change?
Thermochromic paints use liquid crystals or leuco dye technology. After absorbing a certain amount of light or heat, the crystallic or molecular structure of the pigment reversibly changes in such a way that it absorbs and emits light at a different wavelength than at lower temperatures.

Tags

• science
• slime

Badge Links

• Scientist - Experiment