Science Activity: Milk Colouring

We had a late afternoon storm and were stuck inside, so we decided to do some quick fun experiments before dinner.  The kitchen is definitely a great place to find all the goodies you need to play with.

Here one of the experiments we did:

Milk & Colour

Aim:  Harvey loves warm milk so I thought, why don’t we make milk more interesting to him than just a drink…

Apparatus:

  1. Milk
  2. Food colouring
  3. Detergents/dishwashing liquid
  4. Cotton buds/dropper
  5. Paper plates or any kind of large brim container to hold the milk

Method:

  1. Add milk to the plate
  2. Add a few drops of different food colouring at the centre of the plate
  3. Soak the end of a cotton bud with the dishwashing liquid
  4. Take the dishwashing liquid cotton bud and press down to the colour in the milk
  5. Watch what happens

Results/Observation:

Analysis: 

Milk contains:

Soap Molecules:

These molecules have different positive (+ve) and negative (-ve) charges.  Milk fat is non polar (no charge) thus it doesn’t dissolve in water.  When dishwashing liquid is mixed in, the non polar end of the liquid collect the non polar fat milk molecules and reduces the surface tension of milk.   As such, the -ve end of dishwashing liquid line up with +ve end of water  and pushes the food colouring towards the edge of the plate. Hence, due to the higher the fat content in the milk, a cooler explosion of colour is observed 🙂

Conclusion:

Harvey was fascinated by the milk explosion and Milk is no longer just a drink to him 🙂

Picture References:

1. http://academic.brooklyn.cuny.edu/biology/bio4fv/page/polar_c.htm

2. http://www.littlestomaks.com/healthy-fats-for-children/

3. https://moleculesandthings.wordpress.com/

4. http://chemistry.elmhurst.edu/vchembook/554soap.html

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