Lava Lamps

Ingredients

• 1 bottle with a lid

• 5-10 drops of food colouring

• 1 funnel

• 100 ml of water

• Canola oil

• 2 Alka-seltzer tablets

Instructions

1. Add 5 – 10 drops of food colouring to the bottle

2. Place the funnel into the bottle

3. Pour 100 ml of water through the funnel

4. Swirl the bottle to mix the food colouring and water

5. Pour oil into the bottle through the funnel so the bottle is full until about 1 inch from the top

6. Add a quarter of an alka seltzer tablet into the bottle and watch what happens

7. Wait until the bubbling slows down before adding another piece

8. Continue adding this way until you run out of pieces

9. When it stops bubbling you can cap it and repeat later

10. Enjoy! 

What’s Happening?

The alka-seltzer reacts with the water to produce carbon dioxide (CO2) gas bubbles. Alka-Seltzer is both acidic and basic. The tablets contain sodium bicarbonate (a base) and citric acid (an acid) which, when mixed with water, react with each other and produce bubbling carbon dioxide. This creates the bubbles you see in the liquid in the bottle. These stick to the water droplets. The water/gas combo is less dense than the oil, so they rise to the top of the bottle.