P RE L AB Q UESTIONS 1.Define adsorbent, solid support, and eluent in terms of a
ID: 1029441 • Letter: P
Question
PRELAB QUESTIONS
1.Define adsorbent, solid support, and eluent in terms of a chromatography experiment. What is the main difference between wetcolumn chromatography and flash chromatography?
2.What is the difference between regular wet column chromatography and flash chromatography? What are two differences between large scale column chromatography versus a microscale column?
3.Chromatography works because of the differences in polarity. Describe what happens to a mixture you have placed on a chromatographic column as you increase the polarity of the solvents you run through the column.
4.dentify which one of the three methods of analysis (i.e., TLC, IR and melting point) provides information about the structure of an unknown compound. Explain why structural information cannot be obtained using the other two methods.
5.For each of the three components of the spearmint oil on p. 1, state the unique functional group it contains, and list the corresponding peaks for that group that would show up in an infrared spectrum of the material. Would you be able to tell these three components apart by IR spectroscopy?
Explanation / Answer
1 Ans Adsorbent: It is the stationary phase used in chromatography technique which is porous and have high surface area for adsortion of substances poured through the column.
Solid support: It supports the stationary phase or itself acts as the stationary phase.
Eluent: It is the carrier that moves the analytes through the colmn.
The difference between column chromatography and flash chromatography is that, in flash chromatography pressure is applied through use of pump to move the analytes through the column. But, normally in column chromatography, the analytes move withou the application of external pressure but under gravity.
2 Ans. The differences between large scale column chromatography and microscale column chromatography are:
3 Ans. When the polarity of solvent used in column chromatography in increased, the analytes elute faster and comes out faster. This is because the polar solvent molecules will compete for site on the stationary phase with the polar analyte molecules because of which analytes will began to elute faster the more the polarity of the solvent used.
4 Ans. IR provides information about the structure of compound analysed. This is because IR spectrum shows the stretches of the functional groups present and the vibrations in the finger print region of the spectrum is unique for each compound. In TLC, how far the compounds move depends on the polarity of the compounds. Its possible to have different compounds with same Rf. Melting point can be used to identify compounds since each compound has different melting point. It gives information about how strong the bonds are but about the perence of a particular functional group.
Large scale Microscale It is doen in a column depending on the amount of the analyte and also the extent of separation of the analytes. It can be done in a Pasteur pipette. Large amount of sample can be separated and may take time. Small amount of sample can be separated and the eparation is fast.Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.