A student spots two dyes at the origin of a cellulose paper chromatogram and develops…
CHEMISTRY · Single correct · A Level · Chemistry · Chromatography · Chromatography
Problem
A student spots two dyes at the origin of a cellulose paper chromatogram and develops the plate in a 1-propanol/water solvent system. Dye X contains multiple –OH and –NH₂ groups, whereas Dye Y consists largely of non-polar hydrocarbon chains. Which statement best predicts their relative Rf values?
(a) Dye X will have a larger Rf because its polar groups increase solubility in the polar mobile phase and allow it to move farther.
(b) Dye Y will have a larger Rf because it interacts weakly with the polar stationary phase and travels farther with the solvent front.
(c) Dye Y will have a smaller Rf because its non-polar chains are poorly soluble in the propanol/water solvent and therefore remain near the origin.
(d) Dye X and Dye Y will have identical Rf values because both experience hydrogen bonding to the solvent and the paper.