A mixture of benzoic acid and naphthalene was dissolved in tert-butyl methyl ether and the resulting solution was extracted with aqueous sodium bicarbonate. The major organic species (excluding solvent) that is present in the lower layer is?

Benzoic acid

Explanation:

Solvents used are butyl methyl ether and aqueous sodium bicarbonate

Density of tert-butyl methyl ether is 740 kg/m3.

Density of aqueous sodium bicarbonate is 1000 kg/m3.  

Density of tert-butyl methyl ether is less than water, it will form upper layer and aqueous layer will be lower layer.

As density of aqueous solution is higher than the density of tert-butyl methyl ether, therefore aqueous layer will form the lower layer and tert-butyl methyl ether will form the upper layer.

Bicarbonate is basic in nature and benzoic acid is acidic in nature. Therefore, Bicarbonate will form sodium salt of benzoic acid and hence become soluble in aqueous layer (lower layer). Naphthalene won't form any salt with bicarbonate and hence, so it will remain in organic upper layer of tert- butyl methyl ether.

So, benzoic acid will be in lower layer and naphthalene in upper layer.