Question

Why does acetone speed up the rate at which fluorenone travels through alumina stationary phase?

Answer 1

Due to the polarity of the alumina, polarity of the fluorenone and the polarity of the solvent (acetone). Since Fluorenone is polar because of its C=O bond so, remember the rule like dissolves like. This theory also applies to chromatography wherein rather than "dissolve" just replace it with "moves", so like moves with like.

Fluorenone is polar and the dielectric constant of acetone is 20.7 (so it is polar). Since the alumina, acetone, and the fluorenone are all polar, the fluorenone will travel faster through the alumina, because there is no attraction between all these polar compounds which will allow it to move faster, rather than a nonpolar and polar chemical having an attration towards each other and thus moving more slowly.