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Description

Water pepper and washing up liquid experiment

Resources

? **What You Need**

* A **bowl of water**
* Some **ground black pepper**
* A little **dish soap**
* A **cotton bud (or your finger)**

Instructions

Add pepper to a bowl of water, put a drop of washing up liquid on your finger and put your finger in the water, watch the pepper run away from your finger.
? What To Do

1. Pour some **clean water** into the bowl.
2. **Sprinkle pepper** evenly over the surface — it will float on top.
3. **Touch the surface** gently with a **clean finger** — nothing happens; the pepper just stays there.
4. Now **dip your finger (or cotton bud) in dish soap**, then **touch the water again**.

? What Happens - The pepper **instantly shoots away** from your finger, racing to the sides of the bowl!
? Why It Happens (The Science Bit) - Water molecules stick together because of **surface tension** — a kind of invisible “skin” on the water’s surface.

* The pepper floats because it’s very light and can rest on that surface tension.
* When you add **soap**, it **breaks the surface tension**.
* The water molecules move away from the soapy spot to areas where the tension is still strong, dragging the pepper with them.

What It Teaches
* Surface tension keeps light things floating.
* Soap reduces surface tension — that’s how it helps clean grease and break up oils too.

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