Why is benzene separated from water using a separatory funnel?
Miscibility & Density difference
Benzene and water are partially miscible solvents.If we mix alcohol and water they mix together and form a homogeneous mixture. Separating such mixtures require more energy. Hence we use distillation.
But Benzene and water form a non homogeneous mixture, with very little mixing in the interface.We can just let the mixture stand still for long time. They will separate into 2 layers because of the difference in densities. Top layer will be benzene and the bottom layer will be water. Hence we can separate them using a separating funnel.
You are correct, benzene COULD be separated from water by distillation........
But it would be inconvenient, and very tedious to do so........the normal boiling points of water and benzene (
It would be far more convenient to use a sep funnel, and dry the benzene layer after separation. And this is the standard procedure in many organic reactions: (i) do the reaction; (ii) quench the reaction with water; (iii) extract the product with ether or toluene; (iv) dry the organic extract; (v) remove the solvent; (vi) recrystallize or distill the product.
It is also a fact that chemists try to limit their exposure to benzene. All these manipulations would be performed in a well-ventilated hood.