Temperature and The Density of Water science experiment : Fizzics Education


Temperature and The Density of Water

Temperature and The Density of Water

Follow FizzicsEd 150 Science Experiments:

You will need:

One Kettle

Oven mitts

A Funnel

One ice bath

Two identical plastic jars with plastic screw-top lids

Something to make a whole with. E.g. A nail or a drill

Red and blue food colouring.

Adult supervision and help


Simulate ocean currents experiment - materials needed
1 Simulate ocean currents experiment - pushing a nail through a plastic lid

Carefully bore two holes on opposite areas of each of the plastic lids. The larger the hole, the
faster the result of the experiment.

SAFETY: If children are to do this, please ensure that hand drills used are not electrically. Alternatively,
hand drill the lids prior to children commencing the experiment, or use stretched balloons with holes


Fill the 5 litre container with 3 litres of room temperature water.

3 Simulate ocean currents experiment - blue bottle in an ice bath

Fill one of the plastic jars with water, add blue food colouring, screw on the lid and stand it in the ice bath for five minutes.

4 Simulate ocean currents experiment - adding hot water around the red bottle

SAFETY: Adults only. Boil the kettle and allow to cool briefly. Carefully pour the hot water into the other plastic jar and add red food colouring. Screw the lid on whilst wearing the oven mitts for your safety.

5 Simulate ocean currents experiment - cold and hot bottles in the water

Gently lower both jars to the bottom of the 5 litre container, making sure that each jar has the holes in the same vertical position as each other.


Allow the coloured water to seep into the surrounding water. You can speed the process by gently squeezing the sides of the jars. However, be careful not to disturb the main body of water.

7 A television screen showing a distance educator running science experiment with a bell jar, vacuum pump and a cup of water. There is an inset of a remote class on the screen and a video conference camera on top of the television.
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Why Does This Happen?

Warm water will float above cold layers of water because it is less dense.

In still bodies of water such as lakes and dams, very distinct layers of warm and cold water form. This phenomenon is called thermal stratification and has a profound influence on the variety of life found within the lakes and reservoirs. The warmer layer, the epilimnion, typically circulates within itself due to solar-driven convection. The colder layer, the hypolimnion, tends to remain much more still, with the size of the temperature layers changing over the changing seasons.

This is why it’s often more comfortable to swim along the surface of a lake rather than dive down to the colder depths. Find out more about a thermocline, also known as a metalimnion. This is the area whereby the rapid change in water temperature occurs.

Whilst in polar regions there are complex movements of currents disturbing the thermal stratification, warmer water will still float above colder water and produce sharp changes in temperature as the depth changes. Coldwater has more dissolved oxygen and is thereby more conducive to life.

Variables to test

More on variables here

  • What happens if you use salty water?
  • Change the size of the opening of the bottle.
  • Does it matter about which type of liquid that you use?

Learn more!


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