One afternoon, a graduate student set up a silica gel column to chromatograph a mixture of two colourless products whose Rf values were quite close. Suddenly, he

Question

One afternoon, a graduate student set up a silica gel column to chromatograph a mixture of two colourless products whose Rf values were quite close. Suddenly, he

realized that he had tickets to the Leafs game that night. He turned the stopcock to stop collecting eluent, put a cap on the top of the column so as to prevent the solvent from
evaporating, then rushed home. The Leafs lost. The next morning, the graduate student resumed collecting the eluent but, after all was done, he analyzed the fractions he collected by TLC and realized that the two products had come through the column together, instead of having been separated. Why? What happened?

Answer 1

One afternoon, a graduate student set up a silica gel column to chromatograph a mixture of two colourless products whose Rf values were quite close. Suddenly, he

if it is capped, wouldn't there be no relative movement up the column, that is, they diffuse until the concentrations are uniform.