Observe the separation of an emulsion in this simple experiment.
Things Required:
1/4 cup of liquid oil
1/2 cup of water
Blue food colouring
1-quart glass jar with a lid
Directions:
Pour the water into the jar. Add five drops of the food colouring and stir. Slowly, add the liquid oil. Secure the lid and shake the jar vigorously for ten times. Put the jar on a table and observe what happens.
This Is What Happens:
At first, it appears that the liquids have dissolved, but in only seconds three layers start to form. In only minutes two layers are present. Liquid bubbles are present in all the layers.
Science Behind It:
Oil and water are immiscible, meaning they do not mix. A combination of immiscible liquids is called an emulsion. Shaking the jar causes the oil and water to be mixed together, but they immediately start to separate. The heavier water sinks to the bottom carrying with it the trapped bubbles of oil. The centre layer has an even distribution of oil and water, making it heavier than the oil but lighter than water. The top layer is mostly oil with the trapped bubbles of water in it. It takes about eight hours for all of the oil to rise and all of the water to sink. Since only the water is coloured, the food colouring has to be water-soluble.
