Question

Four organic compounds: 2-butanone, n-pentane, propanoic acid, and n-butanol, present as a mixture, are separated by column chromatography using silica gel with benzene as the eluent. What is the expected order of elution of these four organic compounds from first to last?

Answer 1

N-pentane, 2-butanone, butanol, propanoic acid

Step-by-step explanation:

Benzene is the eluent, which is a nonpolar molecule, so it elutes nonpolar molecules. The separation will happen to the less polar to the highest polar compound.

N-pentane is a hydrocarbon, so it's nonpolar and will be the first to eluted by benzene. Second, will be 2-butanone, which is a ketone, and have only one polar center: the bond between O and C, which is not much polar, because they have close electronegativities.

The third will be butanol, which is an alcohol, and have the bond between O and H, which have a larger difference of electronegativities, so it's an extremely polar bond.

Finally, propanoic acid is the most polar compound because it is a carboxyl acid and has two polar centers, the bond between O and C, and between O and H.