Question

48. The value of van der Waals' constant'a' for gases O2,N2.
NH3 and CH4 are 1.360, 1.390, 4.170 and 2.253 litre2-atm
mol-2 respectively. The gas which can be most easily
liquefied is:
(a) O2
(b) N2
(c) NH;
(d) CH4​

Answer 1

Explanation:

Sol. The ease of liquification of a gas depends on their intermolecular force of attraction which in turn is measured in terms of van der Waals’ constant ‘a’. Hence, higher the value of ‘a’, greater the intermolecular force of attraction, easier the liquification. In the present case, NH3 has highest ‘a’, can most easily be liquefied.

ease of liquification is directly proportional to ‘a’.If the value of ‘a’ is more then if we apply even less pressure also the gas can be liquified,so in order to liquify easily we should have more ‘a’. so more ‘a’ =more easily liqification.

As NH3 has higher *a value, it can be easily liquifiable. Such that [rate of liquification is directly proportional to a value]