posted by lou .
Which has a higher Rf value Ibuprofen or mefenamic acid? please please please.i need your answers.
This sounds like a chromatography lab question. You have not told us what the stationary phase is or what solvent is used. Rf is an an experimentally determined value that helps compare speeds of migration of components of the sample. This speed would depend on intermolecular attractions of stationary material, solvent, and sample component toward each other. Not a simple matter. Look up the formulas for the two compounds.
One simple way to compare is to assume that the speed (Rf) would be highest for the molecule that is smaller and/or has the smallest number of highly electronegative atoms like oxygen or nitrogen. This may lead to the right answer. Experimental predictions when you have several interacting variables cannot be guaranteed in advance.
Both are carboxylic acids so it will difficult to predict the Rf.
The mefenamic acid also has an amine group. This will also make the Rf pH dependent.