Chemistry

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Video

Materials

• 1 coin
• 1 pipette (or something else you can drop water from)
• Water

Explanation

Water consists of water molecules that attract each other quite strongly. This means that water holds together, like in raindrops or like in a large mass on top of a coin.

However, gravity from Earth constantly counteract the "stack" of water from growing. This means that the water eventually flows over the edges of the coin causing a lot of bonds between water molecules break.

One often talks about the surface tension of water. This refers to how the surface of water holds together, again because of how water molecules attract each other.

Experiment

You can turn this demonstration into an experiment. This will make it a better science project. To do that, try answering one of the following questions. The answer to the question will be your hypothesis. Then test the hypothesis by doing the experiment.

• What happens if you add some dish soap to the water?
• What happens if you use another liquid, such as milk?
• What happens if you use another coin?

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