PURPOSE: To illustrate adiabatic cooling by producing dry ice.
DESCRIPTION: Carbon dioxide, leaked slowly out of the fire extinguisher onto a black felt cloth, produces dry ice, which can be easily seen. Adiabatic expansion and cooling occur when the CO2 gas comes out of the nozzle under high pressure and expands in the atmosphere. Enough is produced to pass the cloth around the class so that students can feel that it is actually cold.
This experiment is a bit more complicated than simple adiabatic expansion. The carbon dioxide actually exists in the fire extinguisher as a liquid, so that much of the cooling is due to the evaporation of the liquid CO2 before it is ejected from the nozzle.
REFERENCES: (PIRA 4C20.45)
EQUIPMENT: Carbon dioxide fire extinguisher on cart with black felt cloth dry ice collector.
SETUP TIME: None.
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