This magic milk science experiment is a classic for kids of all ages. Using common, nontoxic kitchen supplies, the kids will create vibrant art while learning about the science behind the swirling colors that truly makes this experiment magical.
Get Ready for the Magic Milk Science Experiment:
This science experiment only requires a few common kitchen supplies:
- Milk (we used whole milk)
- Casserole dish, baking pan, or plate
- Food coloring
- Liquid dish soap (make sure it is NOT antibacterial)
- Magic Milk Printable
Print out a couple of copies of the free printable worksheet available below so the kids could keep track of their results.
Once we gathered our supplies, we sat at the kitchen table to do our science experiment. Pour a thin layer of milk into the dish and then the kids chose a few colors they wanted to use.
The kids then squeezed a couple of drops of food coloring into the milk in their dish.
Then, carefully, they dripped one drop of dish soap right into the middle of the colored milk.
Oh my, were there squeals of delight and surprise as they watched the colors scatter like fireworks!
The milk continued to move and mix and scatter the colors as if by magic. It continued for several seconds before coming to rest.
The kids tried to drip more dish soap into the milk, but guess what? Nothing happened the second time around. Why not?
The Science Behind Magic Milk
There are a couple of things going on that explain what is happening behind the magic of magic milk.
First, all liquids have this effect called surface tension. It basically means that the molecules on the surface of the liquid bead together in a little dome because of their molecular bonds. If you have ever filled a cup of water past the rim of the glass you may have noticed how the water forms a dome on top and somehow stays suspended a little above the rim. This is because of surface tension.
In this magic milk experiment the milk and food coloring form a little dome.
However, when dish soap is poured over the surface, the surface tension is broken because the dish soap breaks those bonds. This causes the colored milk to spread out like a flood over the surface of the milk.
The second effect at work here has to do with the interaction between the fat molecules in the milk and the soap molecules.
Soap is made up of two sides:
- one side loves water (it is hydrophilic)
- the other side loves fat and oil (it is hydrophobic).
Soap works by grabbing oils by its hydrophobic side and bonding with water by its hydrophilic side. When the soap is washed away with water, it takes the oils and fats along with it.
When dish soap is dropped into milk, there is a swirl of activity of soap molecules finding and bonding with fat molecules in the milk. With millions of molecules swirling around looking for mates, the colors in the milk get all mixed up! It looks like the milk is erupting for several seconds.
You may notice if you try this magic milk experiment once with whole milk and once with skim that the whole milk swirls for much longer because of the higher fat content in the milk.
If the kids want to repeat this artistic science experiment (they will) be sure to wash the dish out well with warm water and then pour in fresh milk to do it again. Once the milk is contaminated with soap it loses its “magic”.
More Science Activities and Ideas
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