Colour Changing Milk

Report Copyright Infringement View in OSM UK

Description

Colour changing milk experiment is an explosion of colours


Resources

Whole milk (This is important)
red, yellow, blue and green food colours
dish
washing up liquid
cotton buds

Instructions

1) pour about 1cm of milk in a dish - allow to settle
2) add I drop of each food colouring close to each other in the middle of the dish of milk
3) put the end of a cotton bud in the centre of the milk. Do not mix.
4) put a drop of washing up liquid on another cotton bud an put in the centre of the milk again, leave it here for 10-15 seconds, see what happens
5) add another drop of washing up liquid to the cotton bud and watch the colours burst try the cotton bud in other areas of the milk

6) Try setting the same experiment up with water. Is it the same?

GROUP DISCUSSION:
What did the milk look like when you added the dye? Why do you think that is?
What happens when you add the soap? Why did the “dyed milk” disappear? Where do you
think it went?
Why did the colours return after the experiment has been running for a while?

SCIENCE STUFF
Surface tension is an interesting concept, like molecules like to stick together.
Milk has surface tension, just like water, but unlike water, it is high in fat and is solid
coloured. As the dye is less dense (solid/thick), it does not mix into the milk unless stirred.
It remains separate. Washing up liquid breaks down the fat of the milk and decreases the
surface tension in milk. The molecules of fat bend, roll, twist, and contort in all directions as the soap molecules race around to join up with the fat molecules. During all of this fat molecule gymnastics, the food coloring molecules are bumped and shoved everywhere, providing an easy way to observe all the invisible activity. As the soap becomes evenly mixed with the milk, the action slows down and eventually stops.

https://www.youtube.com/watch?v=Hr6dZ6aWpF4


Tags

  • experiment
  • indoors
  • scientist
  • the great indoors

Badge Links

  • Experiment - Experiment
  • Scientist - Experiment
  • Scientist - Other