Let’s observe chemical changes: An explosion of colours


Did you know that we come across chemical changes every day? Many of them appear in our kitchen. And that‘s because cooking involves chemical reactions that result in the flavours, aromas and textures of our foods. And it’s not just that… when we wash our plates, pots and pans, we also set off chemical reactions. The kitchen is an out and out science lab!

With the experiment that we propose today, an explosion of colours, you will discover the behaviour of liquid soap on fat. All you need are 4 things and wanting to have a good time.


  • A deep plate or dish
  • Food colourings (at least 3 different colours)
  • Whole milk
  • Washing up liquid

Follow these steps:

  1. Pour the milk into the plate. Use enough to cover only the bottom part.
  2. Now add drops of the different food colourings to the milk, leaving a space between them.
  3. Next, place a drop of washing up liquid on top of each drop of food colouring.

Carefully observe what happens. You will notice that the food colouring reacts by sinking under the liquid soap only to emerge to the surface again later.

But… do you know why this happens?

This chemical reaction takes place because the main function of dishwashing liquids is to eliminate fat. Milk is an emulsion, which means that it is made up for the most part of water, but it also contains vitamins, minerals, proteins and small droplets of suspended fat.

When we drop the liquid soap into the plate, it breaks up the fat in the milk and this action makes the colours disperse and intermingle in a rainbow of bewitching colours.

Amazing, isn’t it?


Discovery magazine

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