Page 115 - Encyclopedia of Chemical Compounds 3 Vols

AMMONIUM CHLORIDE

Ammonium chloride. White
atoms are hydrogen; blue atom
is nitrogen; and yellow atom is
chlorine. PU BL I S HERS
RESOURCE GRO U P

nature, and only then in arid (dry) regions. Since ammonium
chloride is quite soluble in water, it remains on the ground
only in places where there is little rain. One such location is
around the vents of active volcanoes. The compound is
formed in these regions when hydrogen chloride (HCl) in
volcanic gases and ammonia (NH 3 ) produced by the decay
of plants and animals react with each other to form ammo-
nium chloride, which then settles out onto the ground.

HOW IT IS MADE

One straightforward method of making ammonium
chloride is by combining an aqueous solution of some
compound of ammonia, usually ammonium sulfate
([NH 4 ] 2 SO 4 ), with hydrochloric acid (HCl) and collecting
the ammonium chloride that forms by evaporation. Com-
mercially, the compound is obtained as a by-product of the
so-called ammonia-soda process for making sodium carbo-
nate (Na 2 SO 4 ). In this process, invented by the Belgian
chemist Ernest Solvay (1838–1922) in 1861, ammonia,
sodium chloride (NaCl), and carbon dioxide (CO 2 )are com-
bined with each other in a series of reactions to make

64 CHEMICAL COMPOUNDS