Question

A student needed to determine the percent composition of a mixture that contained fluorene and benzoic acid. The student took 283 mg of the mixture and used the extraction method to separate the components. Then both compounds were recrystallized and dried. The experiment produced 141 mg of fluorene and 105 mg of benzoic acid. Calculate the percent composition of the mixture.

Fluorene = _____%
Benzoic acid = ______%


In order to find the percent composition of fluorene, would I just divide 105 by 283 and then multiply by 100 to get the answer?



Any help would be appreciated! :D

Answer 1

That should give you the percent fluorene and a similar process will calculate percent benzoic acid; however, note that 105 + 141 is not = to 283 mg. Something must be missing from the problem.
1. The sample contained something other than fluorene and benzoic acid, or
2. We assume the extra material was lost during the extraction, either in the aqueous phase or the organic phase (or both) in which case the percent calculated is too low for either/both materials.