Magic Milk experiment is very popular on Pinterest. I came across this a few months back, but didn’t want to waste milk at home. A couple of weeks back we had some milk past best before date, hence tried this. This is a simple activity to discuss about chemical reactions.
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What you need
- 2% or whole milk (i used whole milk)
- food coloring
- dishwashing liquid
- cotton swab (Q-tips)
- Bowl or plate
- Pour enough milk onto a bowl or plate to cover the bottom.
- Add few drops of food color to it. We used red and yellow.
- Dip a cotton swab in dishwashing liquid.
- Dip the coated swab in the milk.
- The colors will swirl as soon as the dishwahing liquid contacts the milk.
This was very interesting to observe. Miss A(3.5) & Miss D(2.5) thoroughly enjoyed watching the colors swirl. They kept doing it until the milk no longer reacted with the dishwashing liquid. At one point A poured in all the dishwashing liquid into the milk to see what happened. They wanted to do this again and again, so we repeated it once more. 😀 I explained to them, that the swirls created is actually a chemical rection between the dishwashing liquid and the fat in milk, but they didn’t really seem to care. The swirls were too mesmerizing. This experiment is something you have to do to see and enjoy the results.
The science behind it
Milk consists of a lot of different types of molecules, including fat, protein, sugars, vitamins, and minerals. If you had just touched a clean cotton swab to the milk (try it!), not much would have happened. The cotton is absorbent, so you would have created a current in the milk, but you wouldn’t have seen anything especially dramatic happen.
When you introduce detergent to the milk, several things happen at once. The detergent lowers the surface tension of the liquid so that the food coloring is free to flow throughout the milk. The detergent reacts with the protein in the milk, altering the shape of those molecules and setting them in motion.
The reaction between the detergent and the fat forms micelles, which is how detergent helps to lift grease off of dirty dishes. As the micelles form, the pigments in the food coloring get pushed around. Eventually. equilibrium is reached, but the swirling of the colors continues for quite a while before stopping.