Gas/Liquid Compression

Squeeze that fluid.

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Purpose -

An interesting way to demonstrate the difference in compressibility between gasses and liquids  

Nature - 

Demonstration

Materials - 

two large syringes, a length of aquarium air tubing. 

Method - 

· Join the two syringes to a length of tubing as shown the figure.

· While full of air push strongly on both syringes (a student helper or two may be of assistance) and note the air inside is able to be compressed to a great degree.

· Fill the apparatus with water and try again.  It should be noted that the water is not compressible to any real degree.

Safety -

Nil.

Explanation -

Because of the large amount of space between the molecules of a gas they are able to be compressed into a smaller space than that which they would like to fill.  Liquids do not have these spaces so they cannot be compressed. 

Notes -

Make sure that the whole apparatus is tight fitting or you may find that one of the junctions between syringe and tube gives way spaying water everywhere.

The ability to compress gasses is what makes SCUBA diving possible, as well as all other gases that are compressed into cylinders.