Question

Which one of the following should have the lowest boiling point? HCl PH3 H2S C2H6 C3H7OH

Answer 1

Answer:

$C_2H_6$

Explanation:

The boiling point depends on the intermolecular forces between the molecules of the compound.

$HCl,\ H_2S\ and\ PH_3$ have dipole- dipole interactions because there is the difference in electronegativity values of the atoms in the molecules.

$C_3H_7OH$ posses hydrogen bonding.

$C_2H_6$ : The bond in the molecule is C-H, which is non-polar in nature because the carbon and the hydrogen having very similar electronegativity values.

The intermolecular force acting in the molecule are induced the dipole-dipole forces or London Dispersion forces / van der Waals forces which are the weakest intermolecular force.

Hence, it has the weakest bond, so it takes least amount of the energy and hence the lowest boiling point.