Preparation of Nitric Acid

Nitric acid (HNO3), also known as aqua fortis and spirit of niter, is a highly corrosive mineral acid.

The synthesis of nitric acid was first recorded ca. 800 AD by the alchemist Jabir ibn Hayyan, a.k.a. Gerber.

Formula: HNO3

Molar Mass: 63.01 g/mol

Density: 1.51 g/cm³

Boiling point: 83 °C

Melting point: -42 °C

This is a very strong acid with a suffocating and pungent odour, highly toxic to inhale, and corrosive to metals and tissues.

Nitric acid is one of the acids in acid rain. Nitrogen Oxide emitted from vehicle engines mix with water vapour in the air and turns into nitric acid. This nitric acid falls from the sky as acid rain.:

This acid is prepared by reaction of nitrogen dioxide (NO2) with water.The commercial production of nitric acid is by oxidizing anhydrous ammonia to nitric oxide, in the presence of a platinum catalyst at a high temperature (Ostwald process).

In this chapter, we will learn in detail about lab preparation of nitric acid.

Physical properties

 Colourless liquid (commercial nitric acid is yellowish brown) with suffocating smell and acidic taste

. Fumes in air and is always placed in a stoppered bottle

. Soluble in water in all proportions

Corrosive can cause blisters on the skin.  Reacts with the protein on skin to form xanthoproteic acid which stains the skin yellow

When oxides of nitrogen dissolve in rain water, they come down to earth as acid rain

Oxidising properties of nitric acid

Being a powerful oxidizing agent, nitric acid reacts violently with many non-metallic compounds. Reactions may be explosive

 Oxidizing properties are because of nascent oxygen which is formed during decomposition of acid

 Nitric acid reacts with metals to form nitrates and is itself reduced to NO, N2O, NO2 or NH3 (which further reacts with HNO3 to give NH4NO3) depending upon the concentration of the acid, activity of the metal and the temperature of the reaction