Why does the solvent move up the paper?
Non-polar molecules in the mixture that you are trying to separate will have little attraction for the water molecules attached to the cellulose, and so will spend most of their time dissolved in the moving solvent. Molecules like this will therefore travel a long way up the paper carried by the solvent.
Polarity has a huge affect on how attracted a chemical is to other substances. The larger the charge difference, the more polar a molecule is. You will find that as you increase the polarity of the solvent, all the components of the mixture move faster during your chromatography experiment.
- Beta carotene is carried the furthest because it is highly soluble in the solvent and because it forms no hydrogen bonds with the chromatography paper fibers. Chlorophylls are bound more tightly to the paper than the other two, so they travel the shortest distance.
- Methylene chloride or dichloromethane is moderately polar. Any small molecule cannot be polar or non polar at the same time * polarity is a range. Chlorine being more electronegative than hydrogen causes the dichloromethane molecule to be slightly more negative on the side of the chlorine atoms.
- Alcohols are less polar than water. This means that alcohols are better solvents of organic molecules. The isopropyl group is large and nonpolar, so isopropyl alcohol is less polar than methanol and ethanol. It is a component of nail polish removers as organic compounds in nail polish become soluble.
Updated: 2nd October 2019