Water Surface Tension Experiment

Instructions:

Watch the black pepper scatter as you break down the water surface tension using soap.


Materials:

  • cereal bowl

  • water

  • ground black pepper

  • liquid soap

  • a toothpick


Directions:

  1. Fill a bowl with water

  2. Shake the black pepper onto the surface of the water (Notice how it stays afloat on the water? That is the surface tension holding the layer up)

  3. Take a toothpick and put the end into soap so that it coats the end

  4. Gently touch the surface of the water with the toothpick

  5. Did you see how the pepper shoots back in all directions? What must the soap be doing to the surface tension?

  6. Soap is something that actually breaks down the cohesive powers of water, making it have less surface tension.

  7. If you mix some soap with water and make a water droplet on your counter again, what do you think the shape would look like? Give it a try!