Question

Which two physical properties allow a mixture to be separated by chromatography

Answer 1

Answer:

                 Option-1 (Solubility and Molecular polarity) is the correct answer.

Explanation:

                        Thin Layer Chromatography is employed to separate a mixture of non volatile compounds. In this technique an adsorbent material like silica gel is coated on a plastic, glass or aluminium sheet. Then the mixture of compounds is applied at the bottom of sheet and the sheet is placed in the container containing a solvent system. It is observed that the solvent starts travelling upward through capillary action.

While the solvent is running the mixture of compounds starts separating from each other. This separation is due to following physical properties.

1) Solubility of Mixture in Solvent:

                                                          In a mixture those compounds which has more solubility in solvent will travel more and will give greater Rf value and the less soluble will left behind with smaller Rf value. Hence due to solubility a mixture of compounds can be separated.

2) Polarity of Molecules:

                                          As the stationary phase (adsorbent material) is polar in nature, so in mixture those compounds which are less polar will less interact with the stationary phase and will travel more with greater Rf value, while, more polar molecules will form stronger interactions with the stationary phase, hence will travel less and therefore, will show smaller Rf values.