Which of the following are necessary steps in performing paper chromatography?    I. Saturate the chamber with the vapor of the mobile phase    II. Allow the chromatogram to touch the sides of the beaker    III. Place the spots at the same height as the solvents    IV. Spot the samples 2 cm apart from each other

7. In gas chromatography, increasing the column length leads to analytes, assuming all other parameters are kept constant. a. no effect on b. an increase in C. a decrease in 8. Suppose you are extracting an organic compound from an aqueous solution using retention time for dichloromethane. a. top layer b. bottom layer Once you mix the two layers together, which layer is the organic extract? 6001 9. Which way is best to remove an acidic impurity from an organic liquid that is immiscible with water? a. simple distillation b. wash with aqueous base c. wash with aqueous acid d. recrystallization it in diegolved in a volatile

4. The paper chromatogram of an unknown mixture is shown below: final solvent level 5.3 ст 6.0 cm B 2.0 cm A 1.0 cm origin A. Using the measured distances find the retention factor of components A, B, and C. B. If the paper was run using hexane as the solvent, (a) which compound is the most polar? (b) the least polar? Explain your answer. C. What would you expect to happen to the Rf values if acetone was used instead of hexane as the solvent?

"Start the chromatography by adjusting the fraction collector to 130 drops per fraction (about 3 mL)." What is the average volume of a drop?

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Consider Table 1, which lists the volumes of the Fe3+ and SCN- solutions used for the continuous variation method. Note that each of the stock solutions is 0.002 M before mixing. What are the initial concentrations of Fe3+ and SCN- for solution 4, where the volumes are both 5 mL? [Initial meaning after they are mixed, but before]they reach equilibrium)

What is the basic principle for Thin layer chromatography? How chromatogram is developed in thin layer chromatography?

In paper chromatography, which of the following may cause premature separation? Select one: a. Using an open system as the chromatographic chamber b. Using a solvent with high polarity c. Using a solvent with low polarity d. Spotting the concentrate below the solvent level e. Spotting the concentrate on the paper only once

3. Compare column, thin-layer, and gas chromatography in terms of: a. mobile phase b. stationary phase.

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