Have you ever seen a lava lamp? Well… in this awesome experiment you can make your own!
You will need
- Tall / large clear glass or plastic cup
- Food colouring
- Fizzy tablet (vitamin C or Alkazeltzor tablets work well)
- Fill the glass a third with tap water.
- Add food colouring of your choice and mix.
- Fill the glass two thirds with oil carefully. Wait for the 2 liquids to settle.
- Add your fizzy tablet.
- What happens if you add more fizzy tablets? Does the reaction happen again?
- What happens if you break your tablet into quarters and drop them all in? Does the reaction go quicker or slower or not change?
- Using warm water at the bottom of your glass. Does this effect the reaction speed?
When the tablet is added to the water there is a reaction which produces carbon dioxide gas. Bubbles of gas are less dense (lighter) than water so they begin to rise to the top. The bubbles of gas drag balls of water through the oil as they rise up. When they reach the top the carbon dioxide bubbles burst leaving a water droplet in the oil. Water is denser (heavier) than the oil so it quickly returns down to the water layer. This produces the up and down movement of water droplets that we see reminding us of lava lamps.