Cub Scout Lava Lamp

Items Needed:

• An inexpensive bottle of cooking oil
• Empty Cup
• Cup of Water
• Food Coloring (you can choose any color)
• Effervescent Antacid Tablets

How To:

• Remove 1/4 of oil from the bottle into an empty cup
• Place about 3-5 drops of food coloring into the cup of water and mix
• Pour the water / food coloring mixture into the oil bottle leaving about 1/2 inch of air. (you may need to use a funnel)
• Break up the Effervescent Antacid Tables and drop one piece in at a time.
• Make sure to never place the lid on the oil bottle as the tablets are dissolving. It will explode and get oil/water everywhere. 

Whats Happening?
You will find that the oil and water will never mix together. The oil naturally will float on top of the water due to the oil having a lower density than the water. The Effervescent antacid tablets release carbon dioxide gas and take some of the water along for the ride as it rises up to the top. The gas escapes as it reaches the top and the water droplets detach and fall back to the bottom. The reason the tablet fizzes in such a way is because it contains citric acid and baking soda (sodium bicarbonate), the two react with water to form sodium citrate and carbon dioxide gas (those are the bubbles that carry the colored water to the top of the bottle). Place the lid on the bottle for storing.

Try This
With the lid attached tightly; Tip the bottle form side to side and see what happens.