questions from 1 to 5 E Chem230 Prelab Thin Layer Chromatography (1) (1).pdf Rea
ID: 532132 • Letter: Q
Question
questions from 1 to 5
E Chem230 Prelab Thin Layer Chromatography (1) (1).pdf Reade Thin layer chromatography TLC) is a technique used to separate and analyze the compounds present in a mixture. TLC can be used to (1) determine the number of compounds (components in a mixture, (2) identify the compounds (components) in a mixture, (3) test the purity of a compound and (4) monitor the progress of a reaction. The 3 main steps in a TLC experiment involve spotting, development and visualization. Example of a TLC plate before it has been developed: Spots of Compound Pencil Line Std Mix Example of a TLC plate after it has been developed: Pencil Line to mark Solvent Front Separated Compounds May not be visible) Type here to search ENG 11:16 PM US 2017-05-27 R160Explanation / Answer
(1)
One method is visualizing the plate under UV lamp. This is used when there is a chromophore present in the compunds.
Second technique involves placing the plate in jar containing iodine crystals. Adsorption of iodine by the compounds makes them appear as dark brown spots against a tan background.
(2)
This is done to avoid the evaporation of solvent from the plate, because if that happens, it will give incorrect Rf readings.
(3)
The separation will not be good, and instead a large plot will be seen.
(5)
Compounds A and B are pure while S is not, because S separates into 3 dots.
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