Question

how do intermolecular forces affect has chromatography and retention time

Answer 1

In a typical chromatography experiment an unknown solute is dissolved in a suitable solvent which is referred to as the stationary phase and passed through a capillary column which is known as the stationary phase. The magnitude of interaction between the solute & the stationary phase as well as between the solute & the mobile phase dictates how fast or slow the solute gets eluted out of the column. The intermolecular forces could be H-bonding interactions, ion-ion, ion-dipole, dipole-dipole or weak london dipersion forces.

For example, consider the interaction between the solute and the stationary phase. A polar solute will interact strongly with a polar stationary phase via strong H-boning or ionic forces. As a result it will be retained in the stationary phase for a longer time (higher retention time) and will elute later. Where a non-polar or less polar solute will show a smaller retention time and will elute sooner.