Question

3. A student is monitoring a reaction using TLC. The chemical reaction converts compound A into compound B, and she uses molecule A as her reference. Compound A has an Rf value of 0.45; while compound B has an Rp of 0.68 in the solvent system being used. a. Draw a picture of her TLC plate at the beginning of the reaction. b. Draw a picture of her TLC plate after 50% completion (50% of the A molecules have been converted to B molecules). Draw a picture of her TLC plate at the end of the reaction (all of the A molecules have been converted to B molecules). d. Why is it better to use a sample of molecule A rather than molecule B to follow the reaction?

Answer 1

com- Reaction - A - Rg = Distance Covered by tested molecule A was taken as vrelerence Distance Covered by solvent. Rf Value of compound A = 0.45 Ref value of Compound B = 0.68 (a) TLC Plate at the begining of reaction. Covered by Thoumit 7 Chromatogocably blate ( stationary phase) laper to prevent on Drop cef reference (Amolecule) euaparation on Drop of reaction mixture. Solvent: Is Application base. Beaken Solvent (Mobile Phase) Let the Height of TLC flate is lounit. (6) TLC Plate after 50%. Completion of reaction. А в 50.l. 50.1. let upto Here distance Covered by Solvent in Sunit. Distance Covered by A = 2 = Dea Distance by A Dis) Pislanca by Soloent 0.45= DA D A= 5x0.45 unit 5 unit DA = 2.25 covered by B R&C Du sunit Distance Covered by B RA (B) = DEBL = 0.68 = DB Do = 5x0.68 unit = 3 Hunit 1DB = 3.4 unit !
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Layer of Solvent - Drop of A Durob of B (34) Sonial](2.25) (C) TLC Plate at End of reaktion. A - B 100.1. Drop of a mill be missed aut from reaction. mixture Solution. let the distance Coverned by the Solvent is lounit. Distance Covered by A conference point ) = 0.45x10= 415 mil reaction mixture) = 0.68x10=bifunt - Layer of Solvent -- boind of Alvelemence) -point of B 11 -- (415) unit (d) # Because at the end of reaction, Point due to a will be tatally disappear and easy to monitor the reaction. # Rf value of A ih Low. So its point will remain very below the layer cef solvent.