To remove impurities, fluorene had to be recrystallized and purified. In a secondary step, 15 mL of ethanol was heated until the solvent reached boiling. Ethanol is the ideal solvent for crystallizing fluorene, because it is polar. Although fluorene is non-polar, it is not too soluble or insoluble in ethanol. The decision to select this solvent also derives from past experiments. Methanol was initially going to be a good solvent for fluorene, but methanol evaporates very quickly. A larger amount of methanol would have been needed to dissolve the impure fluorene, but only a small amount of ethanol is needed to completely dissolve the impure fluorene. Once the ethanol solvent reached boiling, a small amount was added to the flask, just enough to cover the impure fluorene solids. The flask was then heated on a hot plate, and additional hot ethanol was continuously added until the fluorene was completely dissolved (10). As soon as the solid dissolved, the flask was capped and placed in an ice water bath (11). Crystallization has almost occurred