Mini-geyser with Liquid Nitrogen

Dropping a thick-walled straw into liquid nitrogen will produce a geyser effect. This shows a short straw placed into a film cannister filled with liquid nitrogen. Dropping a long straw into a dewar flask of liquid nitrogen can produce a geyser about 50 cm high.

The room-temperature straw is very hot compared to the nitrogen's temperature of 77 K, so that the liquid nitrogen in the straw is quickly heated far above its boiling temperature. It is more-or-less the same phenomenon at the coffee percolator. The walls of the straw must be quite thick to be effective - a typical thin drinking straw does not have sufficient heat capacity to be effective. The straw section used here is actually a stiff plastic tube designed to be used to hold a balloon.

More dramatic geysers can be produced by using longer plastic tubes in a vacuum flask of liquid nitrogen.