Recrystallization Method:
Identify the impurity in the sample and the approximate degree of contamination
Identify a solvent suitable for purifying the impure sample of benzoic acid by crystallization. [An ideal solvent for recrystallization for a substance is a solvent that will
(1) partially dissolve the substance at room temperature,
(2) completely dissolve the substance while hot . In addition, the hot solution of the substance in the solvent, when cooled will allow the substance to form crystalline solid.]
Separate the impurity by mixing the impure sample with minimum amount of the hot solvent and filtering off the insoluble impurity by gravity filtration.
Allow the filtrate to cool slowly to room temperature or below, for the pure substance to crystallize.
Isolate the recrystallized benzoic acid by vacuum filtration, dry the residue and determine the amount of sample recovered. Calculate the % recovery of benzoic acid
Determine the purity of the recrystallized benzoic acid by determining its melting point and comparing this melting point to the value reported in literature.