Pressure is usually measured
in atmospheres or millimeters of mercury; 1 atm = 760 mm of Hg.
As you can see on the previous page, throughout the experiment the
volume is inversely proportional to pressure; or to express matters
another way, the product of pressure and volume is unchanged. This
can be written as
= k - Boyle's law
in which k is a constant that can be evaluated for a particular
temperature from one particular set of pressurevolume conditions.
In the table at the top of the page, this constant k is equal
to 20 liter atmospheres.
If we want to compare two sets of experimental conditions at constant
temperature, designated by subscripts 1 and 2, then Boyle's law
can be written
= P V
Either form of Boyle's law can be used in an actual problem.