Question

A student performs a crystallization on an impure sample of biphenyl. the sample weighs 0.5 g and contains about 5% impurity. based on his knowledge of solubility, the student decides to use benzene as the solvent. after crystallization, the crystals are dried and the final weight is found to be 0.02 g. assume that all steps in the crystallization were performed correctly, there were no spills, and the student lost very little solid on any glassware or in any of the transfers. why is the recovery so low?

Answer 1

Hey There!

The weight of the starting compound includes the weight of the impurty also.When the crystalization techniques are performed ,The original compounds are only soluble in the suitable solvent but not the impurities.Hence in the result we get only the original compound weight.That is why the weight of the crystalization product to ber reduced than the starting compound.