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Invisible Soda

Your pop disappears when you add milk, but what makes the coke vanish?

Milk goes great with a lot of things: cereal, cookies, cake, and pie. You know what's even more incredible to mix with milk? A big ol' bottle of soda! We know what you're thinking, “Soda and milk would be disgusting, together!” You're absolutely correct, but you aren't supposed to drink the mixture! Instead, watch the magic happen when you mix the two.

Experiment Materials

  • 20 oz. bottle of regular (brown) soda
  • 2% milk

Experiment

  1. Open a fresh, new bottle of brown-colored soda. Coke works great, but any brand of regular cola will do.
  2. Carefully pour 2% milk into the bottle with the soda until the bottle is completely full.
  3. Replace the bottle cap and screw it on tightly.
  4. Now, you'll need to exercise some patience. Observe the milk and soda mixture in regular intervals like every half-hour or hour.
  5. What's happening?!? Slowly, but surely, the milk settles at the bottom and the soda becomes invisible. Holy guacamole!

How Does It Work?

Invisible soda? What in the world?!?!

The separation happens because of a reaction between phosphoric acid and milk. Phosphoric acid molecules attach to the molecules of milk, increasing the density and separating them from the rest of the liquid. The remaining liquids, having less density than the phosphoric acid and milk molecules, floats on top.