Fun Chemistry

Impress your friends this summer with fun chemistry activities!

Messy Ooze – Is it a Liquid or a Solid?

 

You will need

• • Newspaper
  • Measuring cups
  • 1 cup of cornflour
  • Large bowl to make your mixture
  • Food colouring
  • 1/2 cup of water

Method

1. Protect your worktop with newspaper
2. Put the cornflour in the bowl, and add any food colouring
3. Add the water slowly and mix with your fingers – enjoy!
4. Add water slowly until the ooze feels like a liquid
5. This is where the fun starts! Try grabbing the ooze slowly with your fingers, what does it feel like?
6. Tap the ooze quickly with a spoon, how different does it feel?
7. Pick a handful, squeeze it, and then stop squeezing, what happens?
8. Take a blob, roll it between your hands quickly and then stop, what do you notice?

 

The science behind it

The mixture is made of tiny solid particles suspended in water – what chemists call a colloid which behave very strangely. If you try to stir the colloid with your hand quickly, it will resist the movement; if you try to stir gently, it will flow easily. Your hand applies a sideways shearing force as it tries to move through the mixture. The water will shear (move out of the way) and it will always flow in the same way. The ooze will flow differently depending on the shearing force applied.

Quicksand behaves similarly to your ooze, so if you ever find yourself sinking in a pool of quicksand, what would you do to get out more easily?