Question

Chlorine is more easily liquefied than ethane because ("a” and "b" are van der waals constants for gases).

• A. a and b for Cl₂ < a and b for C₂H₆
• B. a for Cl₂ <a for C₂H₆ but b for Cl₂ > a for C₂H₆
• C. a for Cl₂ > a for C₂H₆ but b for Cl₂ < a for C₂H₆
• D. a and b for Cl₂ >a and b for C₂H₆

Answer 1

The correct option is C

a for Cl₂ > a for C₂H₆ but b for Cl₂ < a for C₂H₆

$C{l}_2$ is more easily liquefied.

⇒ “ a” for $C{l}_2$ > “a” for $C_2{H}_6$.

This is obvious from theory of compressibility. Greater means more appreciable attractive forces. This initially adds compression and thus liquefaction. Since liquefaction of $C{l}_2$ is easier.

$\Rightarrow$compression at higher pressure are not impeded. The tendency to repel (between individual atoms) at high pressure is lower.

$\Rightarrow$ Excluded volume is lesser for $C{l}_2$ than $C_2{H}_6$. So,” a” for $C{l}_2$ >” a” for $C_2{H}_6$ and “ b” for $C{l}_2$ < “b” for $C_2{H}_6$ .

In other words, Liquefaction $\propto \frac{a}{b}$.