Question

What is the strongest type of intermolecular force between solute and solvent in each solution?

1. ${\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{14}}\left(\mathbf{l}\right){\mathbf{inC}}_{\mathbf{8}}{\mathbf{H}}_{\mathbf{18}}\left(\mathbf{l}\right)$
   
2. ${\mathbf{H}}_{\mathbf{2}}\mathbf{C}\mathbf{=}\mathbf{O}\left(\mathbf{g}\right){\mathbf{inCH}}_{\mathbf{3}}\mathbf{OH}\left(\mathbf{l}\right)$
   
3. ${\mathbf{Br}}_{\mathbf{2}}{\mathbf{inCCl}}_{\mathbf{4}}\left(\mathbf{l}\right)$
   

Short answer

1. ${\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{14}}\left(\mathbf{l}\right){\mathbf{inC}}_{\mathbf{8}}{\mathbf{H}}_{\mathbf{18}}\left(\mathbf{l}\right)$: London Dispersion force
2. ${\mathbf{H}}_{\mathbf{2}}\mathbf{C}\mathbf{=}\mathbf{O}\left(\mathbf{g}\right){\mathbf{inCH}}_{\mathbf{3}}\mathbf{OH}\left(\mathbf{l}\right)$: Hydrogen bonding
3. ${\mathbf{Br}}_{\mathbf{2}}{\mathbf{inCCl}}_{\mathbf{4}}\left(\mathbf{l}\right)$: London dispersion force

Step-by-step solution

Definition of intermolecular force

In a solution, the intermolecular force is defined as the attractive force between the molecules of solute and solvent which is determined from the relative strength within and between the solute and the solvent.

Respective intermolecular forces between solute and solvent in each solution

${\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{14}}\left(\mathbf{l}\right){\mathbf{inC}}_{\mathbf{8}}{\mathbf{H}}_{\mathbf{18}}\left(\mathbf{l}\right)$: London Dispersion force

Both hexane and octane are nonpolar in nature, so the strongest intermolecular force between them is london Dispersion forces.

${\mathbf{H}}_{\mathbf{2}}\mathbf{C}\mathbf{=}\mathbf{O}\left(\mathbf{g}\right){\mathbf{inCH}}_{\mathbf{3}}\mathbf{OH}\left(\mathbf{l}\right)$: Hydrogen bonding

Hydrogen bonding is the strongest because of the polar formaldehyde molecule dissolves in polar solvent i.e., methanol.

${\mathbf{Br}}_{\mathbf{2}}{\mathbf{inCCl}}_{\mathbf{4}}\left(\mathbf{l}\right)$: London dispersion force

Both bromine and CCl₄ are nonpolar, evident from the Lewis structures of the Br₂ (linear) and CCl₄ (tetrahedral).

So, the only strongest intermolecular force here is london dispersion force.