Fireworks in a Jar

Have your very own firework display inside your own home! … Its noise free, but just as colourful!

You will need

  • Tall drinking glass
  • Water
  • Cooking oil
  • Food colouring
  • Fork
  • Small bowl or ramekin

Method

  1. Fill your tall glass ¾ full of water
  2. In a small bowl or ramekin, measure 3 tablespoons of cooking oil
  3. Add a few drops of food colouring (2 or 3 colours) to the oil and mix with a fork to break apart the droplets a bit
  4. Pour all of the oil onto the water and wait for your firework display to start

Investigation

  • Try repeating this experiment with warm water, or ice-cold water. Does it make a difference?
  • What happens if you don’t break apart your droplets of food colouring?

Science

Oil and water do not mix. This is because oil is hydrophobic, which means it is water hating. Oil is also less dense than water, which means it is lighter and will float on top of water.

Food colouring is water based, so oil also doesn’t mix with it. When we add food colouring to oil it will form droplets, and we break these droplets up into smaller droplets with our fork.

When we add the oil and food colouring mix to the glass of water two things start to happen. Firstly we notice that the oil floats and doesn’t mix with water – because it is less dense (lighter) and hydrophobic. But also the food colouring will start to sink towards the water. When the food colouring hits the water it dissolves and produces our ‘firework display’.

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