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Separation of solutions and mixtures chromatography


A chemist is separating a mixture of two substances, X and Y, using column chromatography. The chemist loads the mixture onto a column filled with silica gel (a polar material) and then flows a nonpolar solvent through the column. Partway through running the column (at t=t), the chemist observes the separation of X and Y shown below.
Two images of a chromatography column at two time points labeled t equals zero and t prime. Both images of the column show a column with a stopcock at the bottom. Solvent permeates the column and is draining through the stopcock. The column is packed with silica gel and has a plug of glass wool at the bottom near the stopcock. At t equals 0, a band near the top is labeled X plus Y. At t equals t prime, band X is about halfway down the column while band Y is about two-thirds of the way down the column.
Which substance, X or Y, has the stronger attraction for the stationary phase, and why?
Choose 1 answer: