True or False: A sample of aspirin has actually an $R_f$ value of 0.20 as soon as measured on a silica gel TLC plate through a specific solvent mixture. If the polarity of the solvent is increased, the $R_f$ value of the aspirin will certainly come to be bigger.

Would this be false? Since aspirin is polar (I believe would be thought about polar because it dissolves in water despite some other resources saying that it is actually non-polar) and the silica in the TLC plates are likewise polar, aspirin would certainly not have the ability to take a trip extremely much because it would communicate with the silica. Thus, shorter distance over much longer distance = lower $R_f$ value, through $R_f$ = distance spot moves/ distance solvent moves.

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I wish we would certainly stop teaching chromatography in terms of "polar" and "nonpolar."

The aspirin will certainly communicate reasonably strongly via the silica because of hydrogen bonding/electrostatic interactions of the carboxylic acid and also the ester with the silica. If you boosted the "polar" component of the mobile phase, it would travel better because of the mobile phase completing more for binding spots of the silica gel.

So enhancing the polarity of the mobile phase does raise $mathrmR_f$ of aspirin (or anything) on constant silica gel.


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Since aspirin has actually a carboxylic acid team on it, it would certainly be considered polar. Silica gel, consisting of $ceSiO2$, is additionally polar. Since polar molecules attract other polar molecules, the aspirin molecules will tfinish to bind to the silica and also not move up the TLC plate in a nonpolar eluent, leading to a low $R_f$ value.

When the polarity of the eluent is enhanced, its ability to tempt polar molecules is raised. This means that it can better contend with the silica in attracting the aspirin, and the $R_f$ value will be greater.


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