Question

Describe why silica gel chromatography is a good method of separating methyl orange from biphenyl.

Answer 1

It can be observed from their compositions that methyl orange is a polar compound because of the existence of -SO3Na functional group. The -SO3Na group is ionic in nature and imparts polarity to methyl orange. While biphenyl is a non-polar compound because of the non-existence of polar functional groups in its composition.  

The silica gel chromatography refers to an apparatus, which is used to distinguish molecules on the basis of their polarity variations. The silica gel, that is, a stationary phase is polar in nature, and thus, the non-polar compounds seem to elute prior to the polar ones.  

In the mentioned case, the biphenyl will elute first because of its non-polar characteristic and thus will exhibit high Rf value.