Discussion:
Regarding the polarization of acetanilide and biphenyl. Only the acetanilide was capable of being
dissolved in the water. Most likely due to the fact that it is a polar molecule and would readily dissolve
...
Discussion:
Regarding the polarization of acetanilide and biphenyl. Only the acetanilide was capable of being
dissolved in the water. Most likely due to the fact that it is a polar molecule and would readily dissolve
inside a polar solvent like water. In terms of the temperature of the water throughout the experiment
the purpose for it needing to be so hot in the first portion of the experiment was so that the solid
compounds would dissolve as much as possible due to the heat energy being capable of breaking the
necessary bonds that hold the molecule together. Later in the experiment when the cooling of our
compounds begins, the purpose of this is to recrystallize the solute in solution and eliminate any
impurities that may be present in the solution. The percent yield from this experiment was relatively low
at 51.0% this is likely due to the fact that as a source of error there was some sloppy lab practice
regarding the vacuum filtration whereby not all the acetanilide was extracted instead some was left on
the surrounding edges of the porcelain vacuum cup. Also, when moving the filter paper with the
acetanilide crystals on it was dropped on the lab bench with enough force to have a small amount of the
acetanilide land on the floor thus rendering those crystals contaminated and not fit for this experiment.
To remedy this for next time, being more thorough and careful with our results will be necessary to
remove this source of error from future experiments. Based on the observations the lost crystal mass
was mostly from the gravity filtration. The melting point of our recrystallized solid was 115°C thus
suggesting are very pure substance. Lastly the gravity filtration was used to remove the biphenyl from
the solution, this was due to the water being capable of dissolving the acetanilide but not the biphenyl.
The Rf values of the two compounds were roughly 0.74 for methanol and 0.3 and 0.03 for
ligroin, (each value can be found above in the tables above). This is likely due to the polarity of fluorene
and fluorenone where fluorene is non- polar due to its symmetry and it lacking any highly
electronegative atoms and fluorenone is polar due to it having a ketone functional group. The solvents
however are different, methanol is polar with it having an alcohol functional group and ligroin is nonpolar due to it lacking any highly electronegative atoms similar to fluorene. Based on the results we have
I would conclude that the fluorenone would have a stronger attraction to the silica in the TLC plate, this
is because the fluorenone travelled the furthest on the TLC paper in both trials in the mobile phase.
Now, in terms of the separation of fluorene and fluorenone, it appears that ligroin was the better solvent
as seen above on Figures 1. And 2. If there were to be a way to separate them further perhaps a higher
concentrated solution of ligroin could be used to do so
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