This experiment is simple and kids love it, and it forms a nice bridge between our class about chemistry mixtures where we study how oil and water don’t mix, and our chemical reactions class.

The experiment uses vinegar, baking soda, and oil, and requires just a bit of advance prep.

Prep baking soda ice cubes: Use water, baking soda to make a thin paste. (You can add blue food coloring if desired.) Freeze in ice cube trays.

Activity: 

• Take a jar. Pour in ~one inch of white vinegar, ~two inches of vegetable oil. Point out that the oil and vinegar don’t mix.
• Then add a few drops of yellow or red food coloring. Show how the food coloring goes through the oil without mixing, then mixes into the vinegar.
• Then drop in a baking soda ice cube. Sit back and observe. The bubbles will last quite a while.
• As the baking soda and vinegar react, they release lots of bubbles that rise up through the oil, pop and sink back down. It looks sort of like molten lava bubbling. When the reaction stops, add more vinegar and another ice cube, or start a new jar.