Page 34 - Curriculum Visions Dynamic Book

Hydrochloric acid
Hydrochloric acid, previously also called “muriatic acid”, is the gas hydrogen chloride (HCl) in water. Hydrochloric acid is a natural, strong mineral acid, found close to the site of erupting volcanoes. It is also one of the main acids involved in human digestion, breaking down the food in our stomachs.
Because hydrochloric acid is a strong acid it is a good electrolyte.
Most hydrochloric acid is produced as a byproduct during the manufacture of plastics. Hydrochloric acid is vital for the manufacture
of a common plastic, vinyl (see page 22). It is mainly used in steelworks for cleaning steel, and in extracting metals from their ores.
Demonstration of the reaction of two gases
to make a salt
Two colourless gases, one
in each cylinder, are brought together. The upper one is ammonia, the lower one hydrogen chloride. Ammonia is a base, so the gases react to form a salt.
The reaction produces a “smoke” of white particles of ammonium chloride
(the salt).



Hydrogen chloride gas
Gas jars placed on top of one another and a blocking glass plate in between. The glass plate is removed to allow the gases to mix and react.
Ammonia gas
Ammonium chloride smoke appears where the hydrogen chloride and ammonia gas mix and react.
EQUATION: Hydrogen chloride and ammonia
Hydrogen chloride gas+ ammonia gas ➪ ammonium chloride (solid) HCl(g) + NH3(g) ➪ NH4Cl(s)
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