What's this Science Bite about?
Make your very own own lava lamp with this fun science experiment you can try at home or in school.
Find out about different types of molecules and why oil and water just won't mix!
Always remember to ask a parent or guardian to help you.
What you'll need
- Clear Plastic/Glass Bottle
- Vegetable oil
- Food Colouring (any colour apart from yellow)
How to do this experiment
Follow the instructions in the video below.
Can't see the video above? Watch it on Youtube.
Rinse out your bottle with clean water and remove the label. Now with the help of an adult fill your bottle about ¼ fill with water.
Add a few drops of food colouring and swirl it around to mix it.
With the help of an adult fill the rest of the bottle with oil, leaving a couple of inches space at the top. Cheap supermarket brand vegetable oil works just as well as more expensive brands. Leave the oil and water to separate.
Now drop a few Alka-Seltzer tablets (break them up if they don’t fit) in the bottle and watch as the lava-lamp comes to life!
The Lava-Lamp looks even cooler if you hold a torch behind or underneath it in the dark!
Once the lava-lamp has stopped bubbling you can put a lid on it and save it for when you next want to use it by simply adding more Alka-Seltzer tablets.
Find out more...
Oil and Water are made of different types of molecules that are far too small to be seen. These molecules in a liquid will be close together, they will stick together but able to move about.
Water molecules and oil molecules are held together by different forces. This is complicated but the water molecules are polar (they have very small electrical charges) this is what helps hold them together. Oil is not polar so they do not mix. Oil is less dense than water (light for the same size) so it floats on top of the water.
Why does it bubble?
The Alka-Seltzer reacts with the water and releases a gas called carbon dioxide. The carbon dioxide bubbles stick to water droplets making them less dense than the oil This causes the bubbles and the water to rise through the oil. When they reach the surface of the oil the carbon dioxide is released, the droplets of water then sink again as they are more dense than oil
Properties and uses of materials