Concise Selina Solutions for Class 10 Chemistry Chapter 9 Study of Compounds Ammonia


Ammonia is a compound of nitrogen and hydrogen with the formula NH3. Salts of ammonia have been known from very early times. As early as the thirteenth century, ammonia was known to the alchemists. In 1909, Fintz Haber and Carl Bosch developed a method of producing ammonia from atmospheric nitrogen called the Haber process or the Haber-Bosch process. 

Ammonia has molecular formula NH3 and molecular mass of 17. It occurs in a free state in air and traces of water. In the combined state, it occurs in ammonium chloride, ammonium sulphate etc. A solution of ammonia is alkaline and commonly used in the kitchen as a cleansing agent because it can dissolve grease. Most of the ammonia manufactured is converted into fertilizers like ammonium nitrate or ammonium sulphate. These provide nitrogen to the soil.

  • Ammonia is a colourless gas with a pungent odour. It is a gas at standard temperature and pressure and is corrosive to some materials.
  • It is lighter than air, its density being 0.589 times that of air. It is readily liquefied; the liquid boils at -33.3 °C and solidifies at -77.7 °C to a mass of white crystals. Ammonia quickly dissolves in water. It does not burn soon unless mixed with oxygen.
  • Ammonia occurs in small quantities in the atmosphere, in rainwater, infertile soil and seawater. It exists naturally in humans. The kidneys excrete ammonium ions (NH4+) to neutralize excess acid.