Explain why benzoic acid can be purified using extraction method?

Question

the benzoic acid was dissolved in water and we added Nacl and put it into a separatory funnel then we added chloroform.. we were able to extract the benzoic acid but why is that possible?

Answer 1

Water can hold only so much solute.  In this case, it has both benzoic acid and NaCl.  NaCl is more soluble in water than is benzoic acid, and benzoic acid is more soluble in chloroform than is NaCl.  So, when you add NaCl to the water, it sort of "forces" the benzoic acid out of solution, and into the chloroform layer.  Obviously, the sep funnel is used to separate the two phases, since water and chloroform do not mix.

Answer 2

Actually

Addition of aqueous NaCl helps to separate H2O from an organic layer in extraction. The NaCl is more soluble in water so it takes away the water from the organic layer. This gives primarily benzoic acid in the chloroform with very little water. This is akin to osmosis - solvent moves from an environment of low concentration to one of high concentration to try to dilute the higher concentred solution

Answer 3

Addition of aqueous NaCl helps to separate H2O from an organic layer in extraction. The NaCl is more soluble in water so it takes away the water from the organic layer. This gives primarily benzoic acid in the chloroform with very little water. This is akin to osmosis - solvent moves from an environment of low concentration to one of high concentration to try to dilute the higher concentred solution.