Question

separation of benzoic acid and napthalene by extraction lab

2. You are given a two-phase system containing an aqueous layer and an organic layer, but you don't know which is which, nor do you know the identity of the organic solvent. How could you determine which layer is the aqueous layer?

Answer 1

The best way to know which layer is the aqueous layer is to distinguish them depending on their densities. But here as mentioned in the question you don't know the identity of the organic layer and so you don't know it's density. So, the best ways to identify the aqueous layer layer are as follows

1. Add 4-5 drops of water in the separatory funnel and watch where the water droplets go. If the top layer is the aqueous layer the water droplets will go to the top layer and if bottom layer is the aqueous layer, the water droplets will go to bottom layer.

2. You can also study the relative volume of the water and organic solvent. As you know the volume of water and organic solvent when the extraction procedure was started, you can distinguish the aqueous layer by studying it's relative volume after separation.