Give simple chemical tests to distinhuish between the following pairs of compounds
Phenol and Benzoic acid

Explanation

Phenol `(C_(6)H_(5)OH)` and Benzoic acid `(C_(6)H_(5)COOH)`. These can be distinguished as follows :
(a) Sod bicarbonate test : Benzoic acid is a stronger acid than carbonic acid `(H_(2)O + CO_(2))`, as such it will decomoses sod. Bicarbonate (salt of carbonic acid) to give `CO_(2)`. On the other hand phenol is a weaker acid than carbonic acid. As such it will not decompose sod. bicarbonate.
`underset("Benzoic acid")(C_(6)H_(5)COOH) + NaHCO_(3) rarr C_(6)H_(5)COONa + CO_(2) uarr + H_(2)O`
`underset("Phenol")(C_(6)H_(5)OH) + NaHCO_(3) rarr` NO action.
(b) Ferric chloride test : Phenol gives violet colouration wih neutral `FeCl_(3)` solution while benzoic acid gives buff coloured ppt. of ferric benzoate.