Did you know you can make your own lava lamp using simple household items? You’ll also learn some science on the way.  It’s easy, safe and looks very cool.

What You Do:

  1. Fill an empty glass or flask with some water.
  2. Add some drops of food colouring and mix. We found that we like the patterns produced by red colouring, although we encourage you to try other colours as well. Since food colouring is water-based, it will mix well with the water.
  3. Add some oil. You will notice that it doesn’t mix with the water and stays clearly separated as a top layer. Oil and water just don’t mix.
  4. Break an effervescent tablet into a few small pieces, and drop them in the glass one at a time.
  5. Enjoy the show as the reaction in your lava lamp gets going! Once it slows down, simply add more tablets.

 

What Happened:

Two different scientific principles are at play here: density and polarity.

 

Density shows you how much stuff can fit in a certain amount of space. The scientific equation is density = mass/volume.

 

Water is denser than oil. Since there is more mass in the same volume of water than there is in oil, water will be heavier and be at the bottom. If you first pour the oil in the glass and then add the water, you will see that the water will sink at the bottom.

 

Polarity prevents some types of liquids from mixing. For example, oil and water never mix.

It all has to do with the electrical charge of molecules. Some molecules have their electrical charges distributed in a way to have one end as a negative charge and the other end as a positive charge, just like a magnet. These molecules are called “polar.” Water is one example. One end attracts the other.

Other types of molecules don’t have a positive or negative charge and are called “non-polar.” These will not be attracted to polar molecules. Oil is one example of such molecules.

 

 

This is why oil and water don’t mix.

 

Your lava lamp uses a mixture of polar and non-polar liquids that have different densities; water and oil.

One last thing we need to power up your lava display is an energy source to generate the movement you see in the glass. Real lava lamps use the heat generated from the light. For our experiment, we use effervescent tablets. These produce carbon dioxide gas bubbles, which will stick to the water droplets making them less dense, so they rise to the top of the glass. At the top, the gas bubbles pop and escape into the air, allowing the dense water to sink back to the bottom again until new gas bubbles pick the water back up to the glass once more. This cycle will continue until there are no more carbon dioxide gas bubbles formed by the tablet, in which case, you just have to add a new one.

 

Enjoy the show!

 

PS: Note that real lava lamps use different liquids than water and oil, some which might be hazardous. Also, lava lamps use another scientific principle where some liquids expand as they are heated up, making them lighter.

 

By Tinkerer Science Team