Which one of these questions is answered incorrectly? Only one question is wrong the rest are correct. Those that are marked with – are the selected answers.
Which of the following has the largest influence on compound polarity during chromatography?
A. Dipole interactions
B. Non-covalent interactions
C. Van der Waals forces
- D. Hydrogen bonding
2. What is the proper sequence of events to follow after eluting a TLC plate?
- A. Dry the plate, visualize the plate, develop the plate
B. Develop the plate, dry the plate, visualize the plate
C. Dry the plate, develop the plate, visualize the plate
D. Visualize the plate, dry the plate, develop the plate
3. Safety glasses should be worn
A. until you finish the lab.
-B. at ALL times in the lab.
C. whenever you are working with chemicals.
D. whenever you are working with glassware.
E. when you and your partner begin the experiment.
4. Disposable gloves are strongly discouraged in the laboratory because
A. aqueous chemicals may pass rapidly through the glove and cause harm to the skin.
B. organic chemicals may pass rapidly through the glove and cause harm to the skin.
C. a buildup of sweat inside the glove may cause harm to the skin.
- D. the organic chemicals may cause the gloves to dissolve.
E. it is difficult to manipulate glassware when wearing gloves.
5. If you should get any laboratory chemicals on your skin,
A. wipe the affected area and inform your TA.
- B. wash the affected area immediately with cold water and inform your TA.
C. wear gloves.
D. wash the affected area with cold water.
E. inform your TA.
6. The distribution constant
A. has a characteristic value for a compound.
B. has a characteristic value in a particular solvent system.
C. increases as the concentration decreases.
-D. has a characteristic value for a compound in a particular solvent system.
7. What is the most common absorbent in column chromatography?
A. alumina
B. cellulose
- C. silica gel
D. charcoal
8. A compound that moves quickly through a stationary phase will have Student Response
A. a small Rf value.
B. a small distribution constant.
C. a large distribution constant.
- D. A large Rf value.
9. Venting a separatory funnel should be done by Student Response
- A. inverting and then opening the stopwingspan after shaking.
B. inverting and then opening the stopwingspan before shaking.
C. opening the stopwingspan after shaking.
D. opening the stopper after shaking.
E. opening the stopper before shaking.
10. Addition of salt during an extraction Student Response
A. often produces an emulsion.
B. is undesirable as it introduces impurities.
C. improves extraction of the compound from the organic to the aqueous phase.
D. has a negative effect on the extraction of the compound from the aqueous to the organic phase.
- E. improves extraction of the compound from the aqueous to the organic phase.
