Question

In the flushing and cleaning of columns used in liquid chromatography. A series of solvents are used. Hexane, chloroform, methanol, and water are passed through the column in that order. Rationalize the order in terms of intermolecular forces and the mutual solubility (miscibility) of solvents.

Short answer

Order of solvents in terms of intermolecular forces-

Water>Methanol>chloroform>hexane

Order of solvent in terms of solubility

Water>Methanol>chloroform>hexane

Step-by-step solution

Step 1- Intermolecular forces

In water hydrogen bonding is the strongest followed by the hydrogen bonding in methanol. Chloroform can forms week hydrogen bonding whereas hexane doesn’t form hydrogen bonding. Also, the chloroform has dipole-dipole forces whereas hexane has dispersion forces that are less strong than hydrogen bonding.

Step 2- Solubility

The stronger is the intermolecular forces the greater is the solubility. Hydrogen bonding is strongest in water followed by methanol. Chloroform and hexane both are non-polar molecules, but chloroform can form hydrogen hence it is slightly soluble, and hexane is insoluble.