The temperature, pressure, volume and the amount (moles) of substance of a gas are the factors that affect the behaviour of a gas.The ideal gas equation can be described as a relationship of the above four variables regarding a gas.

PV = nRT                                        The constant R = 8.314 J K^-1 mol^-1                                                                • Any gas which obeys the above relationship under any given temperature and pressure is referred as an ideal gas.

Derivation of Boyle law from the ideal gas equation PV= nRT

For a fixed mass of gas at constant temperature the product nT is constant. As R is constant                           nRT = k (a constant)

  PV = k

That is the pressure of a fixed mass of gas at constant temperature is inversely proportional to the volume of the gas (Boyle Law).

Derivation of Charles law from the ideal gas equation

Derivation of Avogadro’s law from the ideal gas equation

• Molar volume

The molar volume of a gas is the volume of one mole of gas. Molar volume of a gas varies with temperature and pressure. Volume of one mole of a gas at 0 °C and 1 atm is defined as the molar volume of a gas at standard temperature and pressure.

Alternative forms of ideal gas equation

PV = nRT

PV = (w/M)RT

PM = (w/V) RT                                                                                                                                                             PM = dRT                     where d- density

P = (n/V)RT                                                                                                                                                                   P = cRT