Water droplet affected by Leidenfrost Effect: Image by Hullernuc
The Leidenfrost Effect is also known as “film boiling.” This one effect makes water dance on a frying pan, flow uphill, and protects a sausage from burning in hot lead!
Public Safety Message for Testing the Leidenfrost Effect
The Leidenfrost Effect deals with steam and heat. These experiments involve hot objects. Carelessness can lead to personal injury from burns or scalding, or even fires.
Do not perform these experiments while impaired by alcohol, drugs or sleep deprivation. Minors must have parental permission and supervision.
If the heat source has an open flame, be sure that your clothes won’t brush past the flames. Long flowing hair, long loose sleeves, or scarves are all hazards to be eliminated before starting these experiments.
Some types of frying pans will scorch or burn if you heat them with nothing in the pan, so use an old skillet that is no longer the household favorite for this experiment. A heavier frying pan will heat or cool more slowly than a lighter one of the same metal.
Simple Leidenfrost Experiments in a Frying Pan
The minimum lab equipment for this home science experiment is:
- A skillet or frying pan
- A stove top or other heat source
- Clean water at about room temperature
Optional equipment includes:
- An eyedropper to apply the water to the skillet
- A stopwatch to time the effects
- Note-taking supplies, such as a pen or pencil and notebook
- A thermocouple to check the temperature of the skillet
Cool Water and Cool Skillet
Leidenfrost droplet: Image by OgreBot
Set up the dry frying pan on a cold stove. Add a drop of water, from a low height of about two centimetres.
Does the water form a drop and remain in a small puddle? Is the puddle moving anywhere? Did any tiny droplets splash away? It is unlikely anything else of great interest will happen.
Turn Up the Heat
Add enough heat that the water starts to boil; watch for a wisp of steam, or for the droplet’s puddle to shrink.
Remove the skillet from the heat for a moment. Add another drop of water from the same height. Does it sit fairly quietly?
If so, this is experiment number 2. Record the temperature of the skillet (if you have a thermocouple). Use the stopwatch to check how long a new drop of water lasts before it evaporates. Log the results.
More Heat for the Skillet
Keep heating the skillet, and add another drop of water. Watch for the first drop that shows bubbles, but does not “dance around” on the frying pan.
Again, remove the skillet from the heat, check the temperature, and time how long a new drop of water takes to fully evaporate if it bubbles as soon as it lands.
Droplet on a Hot Skillet
Resume heating the skillet, checking with an occasional drop of water until one starts “dancing” when it lands. Do you hear any sounds?
Repeat the “remove from heat and time how long a dancing droplet lasts” test.
The Final Heat of the Race
The final condition is to have the frying pan even hotter. The effects on the drop of water should be louder and more intense than before. Again, record the time.
Clean Up and Cool Down
Unless you plan to fry something, the only responsible action is to cool down the frying pan and ensure no-one comes near the apparatus while anything is hot.
Even if you cook, take care with that frying pan, and allow it to cool somewhat before adding anything to the pan. A wet vegetable or piece of meat might jump out of the frying pan and into the fire, or cooking oil might spatter or heat to its smoking or flash points, if added while the pan is too hot.
Read on To Discover The Expected Results Of This Experiment >>
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