Question

1. What is the purpose of column chromatography 2. What is the stationary phase? Mobile phase? 3. What is the purpose of the cotton (glass wool) in column chromatography? 4. What is the purpose of the sand? 5. Why is it important to prevent the column from drying? 6. What can happen if you disrupt your even layer of silica gel? 7. Which compounds come off the column first, polar or nonpolar? 8. Keyon synthesized acetylferrocene (orange) in organic chemistry lab. When she stopped the reaction, all of the ferrocene (red) had not completely reacted. Now she must separate the two compounds to achieve a pure sample of product. Drawin the three columns (on back) representing the separation of the two compounds. The first column is before the sample is loaded, the second column should represent the loaded column, and the third should properly show the separation of the compound Then state which compound will elute from the column first and why. Acetylferrocene Ferrocene

Answer 1

1. Column chromatography is used for separation of mixture of compounds.

2. Silica is starting phase and solvents or gas are mobile phase in column chromatography.

3. Cotton plugin in tap of column privent silica to come out from column and only solvent will come out from column. So cotton plugin keep stationary phase stable.

4. The sand at the top prevents disruption of the well packed stationary phase when additional solvent (eluent) is added to the column.

5. If you let the column run dry the silica will start to crack and you will get poor separation of your compounds.

6. If even silica gel layer will get disrupted then compounds bound to silica also get disrupted and will get poor separation of compounds.

7. Polar compounds binds more tightly to silica by hydrogen bonding than nonpolar compound, so nonpolar compound will come first from column.

8. In ferrocene and acetylferrocene, acetylferrocene will bind silica due to keton group while ferrocene do not have any functional group so ferrocene will come first through column.