(1) In 1662, Robert Boyle discovered the first of several relationships among gas variables (P, T, V).
(2) It states that, “For a fixed amount of a gas at constant temperature, the gas volume is inversely proportional to the gas pressure.”
Thus, p ∞ 1/v at constant temperature and mass
or P = K/V (where K is constant)
or PV = K or P1V1 = P2V2 = K (For two or more gases)
(3) Graphical representation of Boyle's law: Graph between P and V at constant temperature is called isotherm and is an equilateral (or rectangular) hyperbola. By plotting P versus 1/V, this hyperbola can be converted to a straight line. Other types of isotherms are also shown below,
(4) At constant mass and temperature density of a gas is directly proportional to its pressure and inversely proportional to its volume.
(5) At altitudes, as P is low d of air is less. That is why mountaineers carry oxygen cylinders.