Question

How does paper chromatography separate unknown mixtures? How do compounds to be separated interact with the mobile or stationary phase? Please explain.

Answer 1

In paper chromatography spot the mixture to be separated on one edge of some filter paper and then hang the paper vertically with its lower edge (nearest the spot) dipped in a solvent such as alcohol or water. Capillary action makes the solvent travel up the paper, where it meets and dissolves the mixture the dissolved mixture (mobile phase) slowly travels up the paper (the stationary phase) and separates out into different components. Sometimes these are colored; sometimes you have to color them by adding other substances (called developers or developing fluids) that help you with identification.

In paper chromatography stationery phase is a liquid deposited on the surface of a solid.

As the mobile phase starts to move past the stationery phase, some of its molecules (energetic things that are constantly moving about) are sucked toward the surface of the stationery phase and stick theretemporarily before being pulled back again into the liquid they came from. This exchange of molecules between the surface of the stationery phase and the mobile phase is a kind of partitioning effect It is the basis of separation.