2. The following sketch shows the results of a paper chromatography experiment. At the beginning, pure substances A, B, and C were spotted at the points labeled as "x" marks. The dotted line shows the solvent front. The Rf values of A, B, and C are respectively 0.25, 0.75, and 0.50. Where would you expect the spots for the three substances to be when the experiment is completed? Sketch rough circles. 100 80 60 40 20 B

2. The following sketch shows the results of a paper chromatography experiment. At the beginning, pure substances A, B, and C were spotted at the points labeled as "x" marks. The dotted line shows the solvent front. The Rf values of A, B, and C are respectively 0.25, 0.75, and 0.50. Where would you expect the spots for the three substances to be when the experiment is completed? Sketch rough circles. 100 80 60 40 20 B

EBK A SMALL SCALE APPROACH TO ORGANIC L

4th Edition

ISBN:9781305446021

Author:Lampman

Publisher:Lampman

Chapter91: Gas Chromatography

Section: Chapter Questions

Problem 1P

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Similar questions

a) What would you see if you ran a Thin Layer Chromatography (TLC) on a mixture of the three solids shown below using silica gel as the stationary phase and ethyl acetate/hexanes as the mobile phase? Whichsolid would have the highest Rf and which would have the lowest Rf? Explain b) Would changing the mobile phase (from part a) and increasing thepolarity by introducing small amount of methanol to the mobile phase change the order ofRf of the above 3 compounds? Explain c) Another type of chromatography is Reverse Phase Chromatography. In this type ofchromatography, the stationary phase is non-polar and the mobile phase is polar. If astudent performed Reverse Phase TLC on the mixture of 3 solids (from part a),what would be the order of Rf’s of the compounds? Which would have the lowest Rf andwhich would have the highest Rf?
What will be the result of the following errors in thin layer chromatography? a. Too much sample was applied. b. The level of the developing liquid is higher than the applied spot. 3. If two compounds have Rf values of 0.45 and 0.60, how far will they be separated from each other on a plate when the solvent front has moved to a height of 15 cm?
3. If ferrocene was contaminated with some acetylferrocene after the column, what couldyou do to purify it further?4. Could you use a column to separate a mixture of 3 different compounds? Why or whynot?5. Reverse phase chromatography is a type of column where the stationary phase is verynonpolar. If you were to run a reverse phase column on ferrocene and acetylferrocene,in what order would they elute? How could you test the purity of your samples after thecolumn?
1. What factors can affect a solute's Rf value in thin-layer chromatography?2. Why is it necessary to follow these steps when conducting the experiment? -No contact with the TLC plate should be made with bare hands.-Spots should have a diameter of no more than 1 mm.-Allow sufficient solvent to saturate the chromatography chamber.
5. Would you expect that changing the solvent will change the Rf value of the specific solute? Why?6. Suggest simple reasons why the Ni2+ and Fe3+ ions have different Rf values?7. What forces causes the eluting solution to move the chromatographic support material?
1. In the chromatography plate there are three solutes that move forward: 2cm, 2.5cm and 3cm Which will be more polar? 2. What information does the infrared of the spectroscospy offer?
A student places an unknown sample on a thin-layer chromatography plate and develops it in dichloromethane as a solvent. Only one spot whose Rf is 0.98 is observed. Does this result indicate that the unknown material is a pure compound? If not a pure compound, suggest an alternate procedure to verify the purity of the sample.
1) When you try separating an unknown mixture by normal-phase liquid chromatography with 50% hexane and 50% methyl t-butyl ether, the peaks are too close together. (not resolved) Should you use a higher or lower concentration of hexane in the next run?
What kind of information does a mass spectrometer detector give in gas chromatography that is useful for qualitative analysis? For quantitative analysis?
1) The solvent mixture used in a Paper Chromatography of Metal Ions experiment is a mixture of what two chemicals. 2) Expalin the following terms: Retaintion factor, stationary phase, chromatogrhic mobility elution, detection limit, and resolution. 3) Which of the chemicales used in Paper Chromatography of Metal Ions experiment have hazards associated with them? What are the hazards? Expalin why the ammonia chamber and aueous calcuim sulfide must be kept in faume hood at all times?
When using liquid chromatography to separate a mixture containing at least two compounds , A and B. If a compound A has a distribution coefficient (Kd ) value of 2 and compound B has a Kd value of 2.3 , which would you expect to elute first? Explain your reasoning .
1. What is paper chromatograpy?2. What are the stationary phase and mobile phase in paper chromatograpy?3. What is the principle underlying the paper chromatograpy?4. What is Rf value of a dye or pigment?5. Would you expect that changing the solvent will change the Rf value of the specific solute? Why?6. Suggest simple reasons why the Ni2+ and Fe3+ ions have different Rf values?7. What forces causes the eluting solution to move the chromatographic support material?