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Run Pepper Run

Experiments | 7-14 yrs | Learning Pod

Black Pepper and Dish Soap Experiment

I hate black pepper powder. Black Pepper powder makes me go achoo! Black pepper powder makes food spicy! I want to break the friendship of the black peppers; as they make me cry in front of my friends. How do I do that?

Take a shallow bowl of clear water. Sprinkle some of that irritating black pepper powder in it, all over the surface of the water. The pepper should not sink.

What do you observe? The pepper powder stays together, tightly bound; unnerved by the immersion in water. Darn it!

Now gently immerse your index finger into a dishwashing liquid; take it out; and carefully dip it into the bowl filled with water and pepper. Whoa! Those pesky peppers scatter hither and thither; and their years of friendship have been broken. The soap particles from your finger darted towards the peppers; and the peppers got scared and ran away as fast as they could, wherever their tiny bodies could take them.

Water molecules are very tightly glued to each other. Pepper molecules are hydrophobic, so water is not attracted to them. The water molecules pull their own surface molecules strongly, inward.

Since there is no other outer force attracting the water molecules on the top, the surface of the water is firm. This is surface tension. Soap molecules have the capability of breaking up this surface tension of water.

The water molecules fight back, and even though their surface tension reduces; they still manage to drag those pepper molecules away from the soap molecules, and towards the sides of the bowl.

For more such science experiments and articles, visit Science for Kids.