Question

For real gases, the relation between $P$, $V$ and $T$ is given by van der Waals equation, $\left(P+\frac{an^{2}}{V^{2}}\right) \left(V-nb\right)=nRT$. For the following gases $CH_4$, $CO_2$, $O_2$ $H_2$ which gas will have (i) highest value of $a$ (ii) lowest value of $b$ ?

• A. $\left(i\right) CO_{2}$, $\left(ii\right) H_{2}$
• B. $\left(i\right) CH_{4}$, $\left(ii\right) CO_{2}$
• C. $\left(i\right) H_{2}$, $\left(ii\right) CO_{2}$
• D. $\left(i\right) O_{2}$, $\left(ii\right) H_{2}$

Answer 1

Answer: (A)

$\left(i\right) CO_{2}$, $\left(ii\right) H_{2}$

Answer 2

(i) Order of intermolecular attraction is $CO_{2}$ > $CH_{4}$ > $O_{2}$ >$H_{2}$ In $CO_{2}$ intermolecular forces increases with number of electrons in a molecule. (ii) Size increases in order of $H_{2}