Ideal Gases

When examining the behavior of gases under varying conditions of temperature and pressure, it is
most convenient to treat them as ideal gases. An ideal gas represents a hypothetical gas whose
molecules have no intermolecular forces (that is, they do not interact with each other) and occupy
no volume. Although gases in reality deviate from this idealized behavior, at relatively low pressures
(atmospheric pressure) and high temperatures many gases behave in a nearly ideal fashion.
Therefore, the assumptions used for ideal gases can be applied to real gases with reasonable
accuracy.

BOYLE’S LAW

Experimental studies on the relationship between the pressure and the volume of a gas performed
by Robert Boyle in 1660 led to the formulation of Boyle’s law. His work showed that for a given
gaseous sample held at constant temperature (isothermal conditions), the volume of the gas is
inversely proportional to its pressure:

PV  =   k   or  P 1 V 1     =   P 2 V 2

where k is a proportionality constant and the subscripts 1 and 2 represent two different sets of
conditions. A plot of volume versus pressure for an ideal gas is shown below.

Example: Under  isothermal  conditions, what    would   be  the volume  of  a   1   L   sample  of  helium