Condensation of Butane Gas Under Pressure

Problem Students are probably aware of butane lighters and call the butane liquid gas - although they have observed the liquid butane and the gaseous 

Material Gas liquefying pump (see picture) butane (from the cartridge of a butane burner). 

Procedure Open and fill a gas liquefying pump with butane from the cartridge through replacement of the air. Attach the piston, press strongly into the pressure-resistant test tube and lock it in place. Release the lock again and observe the piston. If one touches the tube with evaporating liquid butane, one can feel a cooling effect. Repeat this procedure several times. 

Observation A large drop of liquid is formed during the compression of the gas liquid butane. When the lock is released, the piston moves out of the tube and the liquid drop turns completely into gaseous butane, the same gas volume as before is to be seen. During evaporation is observed a cooling effect, the temperature of the liquid butane decreases. 

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