COLOUR CHANGING MILK EXPERIMENT
Everyone knows that the entire universe – from huge planets to your glass of milk – is made up of chemicals in some form or another. And although we may be too naive to study the universe, we surely can try to decipher the chemicals that lay beneath the white exterior of milk. So have you ever wondered what milk contains? Here’s a fun hands-on experiment you can try to learn more about the main components of milk.
What you will need:
• A shallow dish
• Food colouring
• Dishwashing soap
• A cotton ear bud
Pour the milk in a shallow dish and put a few drops of food colouring at the centre. Coat the tip of the cotton ear bud in dishwashing soap and gently dip it in the milk. As soon as the ear bud touches the surface of the milk, the food colouring starts swirling around on the surface and moves towards the edge of the dish. Want you know why this happens?
The main constituents of milk are water, fat, proteins, lactose and minerals. Apart form these, it also contains small amounts of pigments, enzymes, vitamins, phospholipids and gases. Of all these, proteins and fats are sensitive to the changes in the milk and react when anything is added to it. When the cotton ear bud covered in dishwashing soap touches the surface of the milk it triggers a chemical reaction. The soap combines with the fat and pushes out the water in the milk, which carries the food colouring with it. This results in the appearance of different patterns on the surface.
If you use more than one colour of food colouring the effect is even more intriguing. While moving around the different colours combine and make a rainbow-like pattern on the surface of the milk. The patterns keep moving around until the dishwashing soap gets evenly mixed with the fat in the milk. If more dishwashing soap is introduced, the colours keep moving around until all the fat in the milk has been separated and has combined with the soap.
This fun experiment serves two purposes, the moving colours on the surface of the milk are a treat to look at as they create a number of abstract patterns, and it also serves as a medium to educate children about the composition of milk and the chemistry behind the experiment. You can also try this with different types of milk, like skim or soy milk, to observe the different results dishwashing soap has on it.
If you also want to find out whether the milk you consume is adulterated or pure, there is a simple way. Just pour a drop of milk on a polished vertical surface and if it stops or moves slowly leaving a white trail behind, the milk is pure. However, if it flows down immediately, it has been a mixed with water.