Explain the action of conc. `HNO_(3)` on phenol (carbolic acid).

Explanation

Conc. nitric acid (nitrating mixture) : When phenol is warmed with a mixture of conc. nitric acid and conc. sulphuric acid (a nitrating mixture or the mixed acid), 2, 4, 6-trinitrophenol, commonly called pictric acid, is formed.