Suppose triphenylmethanol and biphenyl have R¢ values of 0.30 and0.60, respectively, in a certain TLC experiment. Sketch the final appearance of a TLC plate, roughly to scale, including the starting line and solvent front a. for a pure triphenylmethanol sample b. for a triphenylmethanol sample contaminated with bipheny1

Suppose triphenylmethanol and biphenyl have R¢ values of 0.30 and0.60, respectively, in a certain TLC experiment. Sketch the final appearance of a TLC plate, roughly to scale, including the starting line and solvent front a. for a pure triphenylmethanol sample b. for a triphenylmethanol sample contaminated with bipheny1

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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1. What would be the effect of the following errors in chromatographic work? a. Damaged silica gel was used. b. The chipped end of the TLC plate was used as the starting point. c. The solvent front was diagonal during development.
if you wanted to makes the spots travel up the TLC plate further, what solvent ration would you choose and why? 1:2 Ethyl acetate/Hexane, 2:3 Ethyl acetate/ Hexane, or 1:1 Ethyl acetate/Hexane
The following chromatographic peaks indicate the undesirable interaction and separation that taken place. Explain in detail how these undesirable interaction and separation happen for each chromatographic peak. b с d a
3. Draw a hypothetical TLC plate that has a ketone standard (with 6 carbons), an alcohol standard (with 6 carbons), and an unknown in separate lanes. The unknown is actually the alcohol but it is impure with the ketone.
6. Which molecule will have a larger R, on a SiO₂ TLC plate using 10% Ethyl acetate/hexane as eluent? Draw their structures and explain why. Benzoic acid or ethyl benzene?
In what order( top to bottom) would you expect to find naphthalene, butyric acid, and phenyl acetate on a silica gel TLC plate developed with dichloromethane?
Prelaboratory Questions Name Laboratory Section 1. Read the Introduction and Procedure for this experiment, then answer the following ques- tions about preparing a TLC plate. a) Why must you hold the plate only by its edges? b) Why must you use a pencil and not a pen to draw the starting line that is 14 – ½ inch from the bottom end of the plate? c) Why must the starting pencil line be above the level of the solvent on the chamber? d) Why must the sample spot not be too concentrated? (continued on next pa
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(please answer all questions) 5-30. When marking the sample line on a TLC plate, why is it inadvisable to use a ball-point pen? 5-31. A series of dyes is separated by TLC. The data are given below. Calculate the Rf value for each dye. 5-32. Why is it important not to let the level of the elution solvent in a packed chromatographic column drop below thetop of the solid-phase adsorbent? 5-33. What are some advantages of using column chromatography to purify reaction products in the microscalelaboratory? 5-34. Discuss the similarities and dissimilarities of TLC, paper, and column chromatography. 5-35. Discuss the similarities and dissimilarities of HPLC and gas chromatography. 5-36. (a) What are the main advantages of using flash chromatography?(b) How can TLC be used in connection with flash chromatography? 5-37. Using the information presented on the right, please identify and explainwhich spot has an Rf value of 0.5.
What is the purpose of chemically staining a TLC plate using iodine vapor? To increase the Rf values of all compounds on the plate To decrease the Rf values of all compounds on the plate To visualize colorless compounds that react with iodine on the plate To spread out the Rf values of all compounds on the plate more
Which one is the more polar component? Explain.
True or False: Rf values can be used to identify pure compounds, provided that the analysis of the unknown is run simultaneously with the known compound in the same TLC plate.