Question

Huie Turva polar better with higher solvent stationary phase Study Problem: A mixture of organic compounds was analyzed by TLC using different solvent mixtures as mobile pha and the results are presented in the diagram below. Compare the TLC plates A-D with the one on the left and answer th questions: a) How is the polarity of the mobile phase used to TLC plate A comparative with plate on the left? b) How are the Ri's value on the plate A comparative with Rf's values on the left plate? c) How are the Ri's value on the plate A comparative with Rf's values on the left plate? d) How is the polarity of the mobile phase used to TLC plate B comparative with plate on the left? e) Which of the plates below has been developed in the most polar solvent? ;R (s) = 1) Which of the plates below has been developed in the least polar solvent? ;R () = g) Which of the plates will not give a correct representation of the mixture? MA Oo 10% ETOAC 90% hexane 5% ETOAC 20% ETOAC 100% EtOAC 100% hexane 950% heyane 80 hexane

Answer 1

a). Solvents system used in plate A is less polar than the left. Left one is 10% ethyl acetate which is a ploar solvent and A is having only 5% ethyl acetate.

b).A is having lower Rf value compare with the left one, Rf value is depend u on the polarity of mobile phase.

Rf value = distance travelled by the compounds/distance travelled by the solvent

c). b and c is same question

d). Polarity of solvents used in the plate B is higher than the left one which is A. B is having 20% ethyl acetate and A is having 5% ethy acetate. As the concentration of ethyl acetate increase, polarity also increases.

e). C is havig higher polarity compared to all other plate, which is having 100% ethyl acetate.

Rf value = distance travelled by the compounds (1)/distance travelled by the solvent (1) = ( 1/1)= 1

f). D is having the least polar solvent system, where 100% hexane which is highly nonpolar solvents.

Rf value = distance travelled by the compounds/distance travelled by the solvent

distance travelled by the compound = 0

Rf = 0

g). Plate C and D didn't show any separtion of two spots. Spots in your TLC represnts each component and if you look plate A, Plate B and first plate shows two spots (two circles) which tells there is two components in your mixture where in plate C and Plate D shows only one circle or spots becuase it didn't separte.

Hope you uderstand and please rate my answers. Thanks