1. Make a graph of \"the effect of mobile-phase polarity on the Rf of ferrocene
ID: 553451 • Letter: 1
Question
1. Make a graph of "the effect of mobile-phase polarity on the Rf of ferrocene and acetylferrocene". You may use Excel or any other program; no hand-drawn graphs will be accepted. Use the concentration of diethyl ether (%) in the solvent for polarity values (pure petroleum ether is 0% diethyl ether, a 1:1 diethyl ether/petroleum ether mixture is 50% diethyl ether, etc.). Use all of the spots from plates 0 and 1 for the Rf values. Scale each axis according to the full range of possible values using the absolute limits for each idea (“% concentration of ether” and “Rf”). Plot all of your points on a single graph, using color or dot-shape to distinguish the points for ferrocene vs acetylferrocene. Do not connect the dots or include any type of curve fitting or trend analysis; just plot the data points. Remember to include proper title, axis-labels, legend, etc.
Explanation / Answer
Compounds are easily separated using polarity.
Here the two compounds under study are ferrocene which is non-polar and the acetylferrocene which is the polar compound. The mobile phase choosen is non-polar petroleum ether and polarity of it is varied by adding diethylether to it. A pure run of petroleum ether can elute out ferrocene. Whereas, a 1 : 1 mixture of petroleum ether : diethyl ether can elute out acetylferrocene.
Initially only ferrocene moves in petroleum ether. As we increase the percentage of diethylether in the solvent, acetylferrocene Rf value also increases. At all points the Rf of ferrocene is higher than the Rf of acetylferrocene.
Drawn below is a possible graph to represent this situation.
As can be seen above, ferrocene can be eluted out with very low diethylether, whereas, acetylferrocene require 1 : 1 diethylether : petroleum ether solvent for complete elution.
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