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KS2 Science at Home: Week 3

Key Stage 2 Experiment of the week - Food colouring Fireworks!

How does it work?

Food colouring dissolves in water, but not in oil. So when you pour in your food colouring/oil mixture the oil will float at the top of the water because it is less dense, and the food colouring will begin to dissolve once they sink through the oil and into the water.

DSC 5182a

Materials you need

  • Water
  • Oil
  • Food Colouring (Any colour of your choosing)
  • 16 oz clear glass (just under 1 pint)
  • Another 16 oz clear glass
  • A Fork

Instructions

  1. Fill the tall glass almost to the top with room-temperature water.
  1.  Pour 2 tablespoons of oil into the other glass.
  1. Add 2 drops of food colouring to the glass with the oil.
  1. Stir the oil into the food colouring using a fork. Stop once you break the food colouring into smaller drops.
  1. Pour the oil and colouring mixture into the tall glass.
  1. Now watch! The food colouring will slowly sink in the glass, with each droplet expanding outwards as it falls. Looks like fireworks! Right?

Questions to think about

  1. Try using red and blue as you food colouring, and do one drop of blue and one drop of red when you start to mix the oil and food colouring together.
  2. Try doing it without the oil and observe and record how the results are different.
  3. Try using a larger glass, does it change the results?

Some Research for next week: What is the freezing temperature of water? Does this change if you add salt to the water?
We will answer this question with next week’s science experiment!