There are two main types of impurities in hydrogen chlo […]
There are two main types of impurities in hydrogen chloride gas: one is inorganic salts and inorganic acids that are easily soluble in water, and the other is air that is insoluble in water.
The former type of impurities can generally be removed by washing, and concentrated sulfuric acid and concentrated hydrochloric acid are generally selected as detergents.
For removing the air in the hydrogen chloride gas, a method of preparing concentrated hydrochloric acid by water absorption and then desorbing the hydrogen chloride gas from the concentrated hydrochloric acid is generally used.
Since hydrogen chloride and water form an azeotrope, concentrated hydrochloric acid can only partially obtain hydrogen chloride gas during distillation, and at the same time produce a large amount of dilute hydrochloric acid composed of constant boiling.