Leidenfrost Phenomenon

Purpose

To demonstrate the Leidenfrost effect.
 

Equipment

Aluminum sheet on hot plate with squeeze jar of green water.

 

Images

i2-26

Description

Turn on the hot plate to high for about two minutes to pre-heat the aluminum sheet/skillet. Then squirt a few large drops of water (with green food coloring to make it visible) onto the aluminum skillet. The water forms drops which skitter around on the hot plate for an unexpectedly long duration, because of an insulating layer of water vapor (steam). Big drops can be created which will persist for a minute or longer, while executing interesting oscillations. This is known as the Leidenfrost phenomenon.
 

References

Owen F. Gaede, A Thought-Provoking Demonstratio in Heat, TPT 15, 487-488, (1977). Jearl Walker, Drops of Water Dance on a Hot Skillet and The Experimenter Walks on Hot Coals, The Amateur Scientist, ?,126-131, (?). G. Guido Lavalle, P. Carrica, V. Garea, and M. Jaime, A boiling heat transfer paradox, AJP 60, 593-597 (1992).