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Hydrogen Chloride : Preparation, Properties and Uses

In 1648, Glouber obtained Hydrogen Chloride Gas by heating sodium chloride (common salt) and concentrated sulfuric acid. Debi proved in 1810 that it is a compound of hydrogen and chlorine.

Hence it was named Hydrochloric Acid. It is also called acid of salt. The aqueous solution of hydrogen chloride gas is called hydrochloric acid.

Occurrence and Availability

It is present in various gases emanating from the eruption of volcanic mountains. It is found in 0.2 to 0.4 percent quantity in gastric juices. Many chloride salts are found in nature.

Preparation of Hydrogen Chloride

Laboratory Method

In laboratory, hydrogen chloride is prepared by heating sodium chloride with concentrated sulfuric acid.

NaCl + H2SO4 NaHSO4 + HCl

NaHSO4 + NaCl Na2SO4 + HCl

Chemical Equipment for this Method :- Round bottom flask , thisil keep, NaCl, H2SO4, glass tube bent twice at right angles, a cork with two holes , gas jar , sprit lamp etc.

Process

Take a little sodium chloride in a round bottom flask. Tighten the flask in the stand. In this flask, a cork with two holes is put. Keep thisil in one hole and put the exhaust pipe in the other. The other end of the exhaust pipe is connected to a gas jar.

The gas is collected in the gas jar by the upward displacement of air.

Hydrogen chloride Preparation

Now pour so much concentrated sulfuric acid from thisil keep that the lower violence of the keep gets immersed in the acid. The reaction takes place in a cold solution and HCl gas is formed, but after some time the rate of reaction slows down, when the flask is heated slowly, due to which the reaction starts taking place rapidly.

Drying the gas: To dry the gas, it is passed through concentrated H2SO4. To dry the gas, phosphorus pentaoxide or unslaked lime (CaO) is not used, because HCl gas reacts with both these substances.

Precautions

The lower end of thistle tube should be immersed in concentrated H2SO4.

Equipment must be airtight.

The gas jar should be used only after drying it thoroughly.

Other Method

Some other major methods of manufacturing hydrogen chloride gas are as follows –

Synthesis Method: In the presence of sunlight, hydrogen and chlorine combine to form hydrogen chloride gas.

H2 + Cl2 2HCl

Reaction with chlorine to water :- When chlorine gas reacts with water, hydrogen chloride gas is formed –

2H2O + 2Cl2 4HCl + O2

Reaction of chlorine with H2S – When chlorine reacts with hydrogen sulfide, hydrogen chloride gas is obtained –

H2S + Cl2 2HCl + S