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The Leidenfrost Effect: Making Water Dance on the Surface of a Hot Pan

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Author: TaniaDakka

You know water boils at 100º C (212º F). But did you know that you can make water dance too? You can! It’s called the Leidenfrost Effect. By adding a water droplet to a pan of boiling water, you can set the stage for H2O to get grooving. Let’s look at the amount of water you need to add to make the Leidenfrost Effect most effective, and get the party started!

Problem

How does the size of the water droplet affect the movement of the water on the surface of a hot pan?

Materials

  • 1 Hot plate or stove
  • 1 Pan
  • 1 Bowl of water at room temperature
  • 1 Bottle of water at room temperature
  • Safety goggles
  • Heat resistant gloves
  • 1 Adult lab assistant
  • 1 Eye dropper
  • 1 Turkey baster
  • Pen and paper to record observations

Procedure

  1. Put on your safety gear (Be careful! You’ll be dealing with steam and heat in this experiment!).
  2. Place the cold pan on the cold stove or hot plate.
  3. Using your droplet, add a drop of water from a low height (about 2 cm).
  4. Observe and record what you saw. What did the droplet do when it hit the pan?
  5. Turn on the burner of the stove or hot plate.
  6. Add enough heat for the water droplet in the pan to boil.
  7. Once the drop has evaporated, drop an eye dropper of water into the pan again.
  8. Remove the pan from the heat for a moment. 
  9. Record what you observed about the water droplet’s behavior (How long does the drop dance on the surface? In what direction?).
  10. When the previous drop evaporates, use the turkey baster to add a bigger drop of water to the surface of the pan.
  11. Observe and record again.
  12. Let the water evaporate.
  13. Pour a few drops of water from the water bottle into the pan.
  14. Record your final observations .

Results

The drops of water dance in a star-like pattern. The larger the drops of water are, the longer it takes for the water to stop floating on the surface of the pan and evaporate.

Why?

The Leidenfrost Effect says that when the temperature of the pan gets hotter than the boiling point of water, as the water droplets hit the surface, the “bottom” of the droplet vaporizes so quickly that the vapor insulates the rest of the droplet and makes it float on the hot surface of the pan. This insulation and floating causes the dancing effect.

Digging Deeper

If you want to take this experiment further, try testing different temperatures. Try it with pans made of different materials like copper, aluminum and cast iron to see which ones demonstrate the Leidenfrost Effect better. There are loads of ways to try this—just be sure to only change one variable at a time for maximum accuracy of your experiment!

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