What is Density?

Science Sparks are very excited to share another fun science activity today, this time it’s a super simple demonstration of density.

What is density?

We’ve made a rainbow glass before, but today we are doing a much more simple version and adding a bit of LEGO. This is a really cool demonstration to explain the concept of density.

What you need

Vegetable oil

Water

LEGO or other small objects.

Density Jar Instructions

Pour some water carefully into a glass or jar.

Very carefully add about the same volume of cooking oil on top.

Then drop a couple of small objects into the mixture and observe what happens. Can you find something to float on each layer?

What happens if you shake it?

What is density?

Each of the liquids have a different mass of molecules or different numbers of parts squashed into the same volume of liquid, this makes them have different densities and therefore one can sit on top of the other – the more dense a liquid is the heavier it is.

Objects and liquids float on liquids of a higher density and sink through liquids of lower density. The LEGO brick  sinks through the oil but floats on the water, while the coin sinks through both. The coin is therefore more dense than both the oil and the water. The plastic bug floating on the oil is less dense than both.

More density experiments

Making your own lava lamp is another great example of oil and water not mixing.

Show your friends a science magic trick which is also a fantastic density demonstration.