Water augmentation

After a while, the water in the bottle begins to rise and a kind of water cap forms. As it heats up further, the water begins to run down the side of the bottle.

The bottle is filled to the brim with water. You then enclose the bottle with both hands and start to warm it up.

• 1 bottle,
• water,

The greater the temperature differences, the better the experiment works.

What is technically behind the experiment

The hands not only heat the bottle, but also the water inside. Due to the heating, the water tends to expand. This means that the volume of the water increases. It tries to escape and always looks for the easiest way out. In this experiment, this is upwards, as the material of the bottle cannot expand with it. The surface tension of the water is still high enough at the beginning to create a real little cap. If you continue to heat the bottle with your hands, the tension becomes too great and small drops run down the edge of the bottle.

What the experiment has to do with everyday life

Liquid thermometers work according to this principle.

Which experiments go well with this

1. heating with hot water instead of using your hands:

Place the bottle of cold water in a container of hot water (heated with an immersion heater) and you will see the water rise faster than in the first experiment.

2. thermal expansion of different liquids:

Since different liquids of the same volume expand differently, you could, for example, place milk, oil and water, which are in 3 Erlenmeyer flasks of the same size, in a container with warm water and observe the different volume expansion constants.

Sinje Geer