A piece of chromatography paper is spotted with a solution containing two components, X and Y. The chemical affinity of X for the sorbant is greater than that of Y, and the solubility of X in the eluent is less than that of Y. Which substance will have the largest R_f value after ascending paper chromatography has taken place? Explain. Why should an unknown be run simultaneously with the knowns, if possible? List two advantages of TLC over paper chromatography. List three factors that can affect the R_f value of a given component.