There are potions all throughout the Harry Potter books. The one doesn’t connect to any specific potion from the series, but it’s a fun one that bubbles and moves in a way that seems almost magical. 

Here is what to do, 

  1. Gather your supplies
    • Vegetable oil
    • Water
    • Food coloring
    • Jar, bottle, glass, or flask
    • Spoon or stir stick 
    • Alka-seltzer tablets
  2. Prepare your mixture in the jar or bottle – pour about twice as much vegetable oil into the jar as water. (This doesn’t have to be exact, but something like 1 cup oil and ½ cup water, for example). 
  3. Add food coloring and stir or shake it up – pause after this to let the layers settle
  4. Drop in the Alka-seltzer tablet and observe 

There are a few different things going on with this potion. First, we are seeing some solubility effects. Solubility is how things mix with each other (or don’t). The water and oil don’t mix with each other because they aren’t soluble. The food coloring is water based so it is only soluble with the water layer and only mixes into that layer. We are also seeing some density effects – the more dense layer is on the bottom and the less dense layer is on the top. Then, we are seeing the impacts of a chemical reaction that forms a gas. When we add the Alka-seltzer tablet, it starts to dissolve in the water and release bubbles. As the bubbles rise to the top of the jar (because they are less dense), they carry water with them. The water drops don’t mix in with the oil as they move through that layer because they still aren’t soluble with the oil. Eventually the bubbles reach the top and the water drops fall back to the bottom based on density.

Watch here: