This week I found a very fun way to teach children at my STEAM class about different densities and chemical reaction of neutralization between acids and bases. We made a glowing lava lamp.
Materials needed: Vegetable oil, Food coloring, Small cup, Baking soda, Vinegar, Long Bottle/cup, Spoon, Flashlight, Dark Room
Procedure:
Take out your long bottle or tall cup and add three table spoons to the bottom of it and make sure it covers the entire bottom of the bottle/cup.
Now in the same long bottle/tall cup fill two thirds of the container with vegetable oil, however this also works with olive oil.
In your SMALL cup, fill about half the cup with vinegar and add your food coloring. This will be the floating bubbles inside your mixture.
Now add drops of the vinegar solution into your large bottle/tall cup.
To make your lava lamp glow, step into a dark room and turn on a flashlight to put under the bottle. Your lava lamp should start to glow.
Here is a video to watch that can show you the procedure and the finished project: https://www.youtube.com/watch?time_continue=228&v=EdSZRmIj4gA&feature=emb_title
Science behind the Lava Lamp: The oil and vinegar have different densities. Vinegar is more dense than vegetable oil, which is why the vinegar droplets sink to the bottom of the tall container. Once the vinegar droplets reach the bottom of the container, it begins to react with the baking soda. The chemical reaction between the vinegar (CH3COOH) and baking soda (NaHCO3) creates sodium acetate (CH3COONa), water (H2O) and the carbon dioxide (CO2). Carbon dioxide creates the bubbles that you will notice in your own lava lamp.This reaction is between acid (acetic acid in vinegar) and base (sodium bicarbonate in baking soda) that creates new components: the salt-sodium acetate, water and carbon dioxide. In chemistry, acids and bases neutralize each other and general formula for the reaction is acid+base=salt+water. That what happened in our lava lamp with addition of carbon dioxide that made the bubbles.
Just a quick suggestion: If you are using olive oil I have found that making a darker blue vinegar mixture looks very cool. WARNING: DO NOT CAP THE BOTTLE THAT IS YOUR LAVA LAMP.