NEXT: Crestmead

Liquid Sandwich

Image of a person with a glass with layers of liquids

Create layers of liquid and see how not all liquids mix together

Australian Curriculum links

  • Science > Chemical Sciences > Year 6 > ACSSU095

You’ll need

  • A tall glass
  • Food colouring
  • Water
  • Cooking oil
  • Honey
  • Small objects, such as
    • paperclip, marble, wood

Try this

  1. Add a few drops of food colouring to your water.
  2. Pour some water into the glass so it is around one quarter full.
  3. Now pour the same amount of honey into the glass. Does the honey sit above or below the water?
  4. Pour the same amount of oil into the glass. Where does the oil sit?

Further investigation

  • Try gently dropping a range of small objects into the tall glass. Where do you think they will float? Make a prediction and then test it out.
  • What happens if you drop a fizzy tablet, such as aspro clear, into the water? How do the bubbles travel through the different liquids?
  • Legend has it, that you can create a seven layer liquid sandwich- do you think it is possible? Liquids that are used (from most to least dense) are: honey, corn syrup, detergent, water, vegetable oil, rubbing alcohol and lamp oil. To create this you may want to use a pipette to help pour the liquids

What’s happening?

The liquids settle out in different layers because they have different densities. An object’s density describes how much mass a given volume of that object has, or how ‘tightly packed’ the material that makes up the object is. If you have the same volume of two different fluids (eg, oil and honey), the denser fluid (honey) will weigh more. You could investigate this as an extension to this activity using a set of scales. 

Honey is the most dense of the three fluids used. It sits at the bottom of the glass. The next layer is water. Oil is less dense than both honey and water so it sits at the top. If the solid that is placed in the fluid weighs less than the volume of the fluid it displaces (or pushes out of the way), the object will float. You can learn more about the science of floating and sinking by reading the ‘can you make a submarine that floats and sinks?’ activity.

Real world links

While differing liquid densities may be used industrially, we probably see them most often in fancy drinks! A tropical sunrise (or tequila sunrise if you’re over 18), layers orange juice on top of red grenadine syrup to create a beautiful sunrise effect.