Speedboat matchsticks

You will require:
• Water
• Bowl
• Dishwashing liquid
• Matchsticks

Procedure:
1. Fill the bowl with water.
2. Gently float a few matchsticks in the water.
3. Drop smalls amount of dishwashing liquid into the centre of the bowl. (It is easiest to do this with another matchstick.) Note what happens.

What is happening?
You notice that as soon as you drop the dishwashing liquid on the water, the matches shoot across the surface of the water like power boats, away from the dishwashing liquid.

This is because, water molecules are strongly attracted to each other and stick  together.

This creates a strong but flexible ‚skin‘ on the water‘s surface, called surface tension. Surface tension allows the matchstick to float on the water.

Adding soap disrupts the arrangement of the water molecules.

The water molecules near the dishwashing liquid are attracted to the molecules in the dishwashing liquid as well as to other water molecules, so the surface tension is broken.

As a result, water molecules move from that area of low surface tension (where the dishwashing liquid was dropped) to areas of high surface tension (away from the dishwashing liquid). The matchstick is pulled towards the areas of high surface tension by the water in front of it, hence the shooting motion.