Help please, I am very confused if you could explain the answers The course of a
ID: 499085 • Letter: H
Question
Help please, I am very confused if you could explain the answers
The course of a chemical reaction (A + B rightarrow C) was followed by TLC analysis at different times after the reaction was initiated. The TLC plates of the reaction mixture at time zero, and after 15 and 30 minutes of reaction, run under identical conditions, are shown in the figure below. The R_f values of pure sample of A and B (under identical conditions) are 0.2 and 0.8 respectively. (a) Calculate the Rf of all the spots. (b) Identify the spots and explain the TLC results. (c) What compound was the limiting reagent in the preparation of C? Briefly justify your answer.Explanation / Answer
a)
Rf for top spot --> 0.80 alwys
Rf for lower spot --< 0.20 always
Rf for medium spot --> 1/4*(0.8+0.2) = 0.25 approx
b)
A = 0.2, the most polar
B = 0.8, the least polar
C = 0.25, between A and B
Expect C to be a mix of A+B+C, therefore it carries all characteristics, since C is nearest to A, this must explain that the limiting reactant A
c)
limiting reagent in preparation of C must be A, since there is higher affinity toward it
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