Q.Match the pairs of the following : 'A' a. Boyle's law b. Charles' law 'B' i. at constant pressure and volume ii. at constant temperature iii. at constant pressure

The van der Waals equation, (P + an²/V²)(V − nb) = nRT, modifies the ideal gas law with two correction terms — one for intermolecular attractive forces (a) and one for the finite size of molecules (b).

Real gases deviate from ideal behaviour because (i) gas molecules do occupy a small but finite volume, and (ii) there are weak intermolecular attractive forces between them, both of which the ideal gas equation PV = nRT ignores. Van der Waals introduced two correction terms:

• Pressure correction: an²/V² is added to the observed pressure P, because intermolecular attractions reduce the pressure a gas actually exerts. …

Charles' law states that, at constant pressure, the volume of a fixed amount of gas is directly proportional to its absolute (Kelvin) temperature: V ∝ T.

Jacques Charles found experimentally that when the pressure and amount of a gas are held constant, its volume increases in direct proportion to its absolute temperature. This is expr …