Question

The boiling points for the homonuclear diatomic molecules in the halogen family are 85 K, 238 K, 332 K, 457 K and 610 K. Which species would you expect to have the boiling point of 238 K?

Answer 1

Answer:

$Cl_{2}$ has boiling point of 238 K

Explanation:

Boiling point depends on different intermolecular force such as molecular wight, dipole-dipole attraction force, hydrogen bonding, ionic attraction force.

Homonuclear diatomic molecules are covalent non-polar molecules and thereby free from dipole-dipole attraction force, hydrogen bonding and ionic interaction forces.

Hence, boiling point of homonuclear diatomic molecules depends solely on molecular weight.

We know, higher the molecular weight of a molecule, higher will be its boiling point. This phenomenon can be realized in terms of increasing london dispersion force with increase in molecular weight.

Decreasing order of molecular weight of halogen molecules :

$I_{2}$ > $Br_{2}$ > $Cl_{2}$ > $F_{2}$

So, decresing order of boiling point of halogen molecules:

$I_{2}$ > $Br_{2}$ > $Cl_{2}$ > $F_{2}$

Hence $Cl_{2}$ has boiling point of 238 K