Question

For real gases the relation between p, V and T is given by van der Waals equation:

`p + (an^2)/V^2 (V - nb) = nRT`

where ‘a’ and ‘b’ are van der Waals constants, ‘nb’ is approximately equal to the total volume of the molecules of a gas. ‘a’ is the measure of magnitude of intermolecular attraction.

Arrange the following gases in the increasing order of ‘b’. Give reason.

\[\ce{O2, CO2, H2, He}\]

Answer 1

The increasing order of ‘b’ of the given gases is \[\ce{H2 < He < O2 < CO2}\]

Volume of a gas is proportional to the size of the molecule.