CHEMISTRY · Single correct · A Level · Chemistry · Chromatography · Chromatography
Problem
During a silica gel TLC analysis of phenol, the developed plate shows a distinct tailing streak rather than a compact circular spot, even though other compounds on the same plate give sharp spots. Which factor most plausibly accounts for the tailing observed for phenol?
(a) Phenol is largely non-polar, so it dissolves almost completely in the mobile phase and travels with the solvent front, leaving a streak along the plate.
(b) The phenol spot was overloaded; excess sample cannot be retained as a compact band and therefore streaks during development.
(c) Phenol forms strong hydrogen bonds with surface silanol groups on the silica gel, creating heterogeneous, stronger interactions that retard and smear its movement.
(d) Phenol partially ionizes to phenoxide on the plate, and the mixture of charged and neutral species migrates at different rates, producing a tail.