Question

the melting point of pure benzoic acid and pure naphthol are 122.5 and 123 degree Celsius respectively. you are given a pure sample that is known to be either pure benzoic acid or 2- naphthol. describe a procedure you will use to determine the identity of the sample.

Answer 1

Perform a mixed melting point; i.e., mix the unknown with pure benzoic acid and determine the m.p. If the unknown is benzoic acid the mixed m.p. will be 122.5 +/- a little depending upon how pure the unknown sample and pure benzoic acid are. If the mixed m.p. is lowered significantly, the unknown must be 2-naphthol. That will be sufficient to identify the compound BUT if you want to make sure, do a mixed melting point with pure 2-naphthol and the unknown