DIY Chemistry: Coca-Cola and Milk

Mixing different liquids together to see what they taste like seems like a part of human nature. But have you ever mixed your favorite drinks together just to see if a chemical reaction will occur? This is an experiment that you can easily DIY, but we do not recommend drinking it. All you need is a bottle of coke and a bit of whole milk.

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Pour the the milk into the full bottle of coke to top it off and then put the cap back on. Mix gently and then keep an eye on it for about an hour.


There is a chemical reaction that occurs between the Phosphoric Acid in the coca-cola and the calcium in the milk.

3Ca + 2H3PO4 ///\\\ Ca3(PO4)2 + 3H2

The reaction creates a precipitate, or solid matter, that is more dense than the liquids, therefore sinking to the bottom of the bottle. This precipitate is mostly just milk that has curdled, or become a solid.

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Now that you have separated the liquid and precipitate, try mixing them back together. A simple way to do this is by simply removing the bottle cap. There was a build of pressure in the bottle due to the chemical reactions. Once the bottle cap is removed the change in pressure allows the mixture to recombine. Enjoy!

Written By: Mimi Garai


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