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Hydrogen Chloride

Hydrogen chloride is a chemical compound having the molecular formula HCl. The molar mass of hydrogen chloride is 36.5g. Hydrogen chloride is a colorless glass at room temperature. It produces white fumes when it comes in contact with humidity which is present in atmosphere and the white fume is called hydrochloric acid.



This hydrochloric acid is derived from the aqueous solution of hydrogen chloride. The melting and boiling point of hydrogen chloride are -114.2˚ and -85.1˚C. It is soluble in water. Hydrogen chloride is a linear shaped covalent compound. The other names for this covalent compound are chlorohydric acid, hydrochloric acid, etc.The molecular formula and the molecular model of covalent bonded hydrogen chloride are as shown below,Molecular formula of hydrogen chloride Hydrogen chloride structureHydrogen chloride is a linear shaped molecule. 


The bond length is 127.4pm and the bond angle is 180˚. There is a covalent bond between hydrogen and chlorine atoms.Bonding of hydrogen chloride:There is a covalent bond between hydrogen and chloride ion but not ionic. It is because, if it is to be ionic it has to lose one or more electrons from hydrogen or chlorine atoms. It is not possible for hydrogen chloride because in hydrogen atom only one electron is present, so it has covalent compound and it has intermolecular bonds which are called London dispersion forces and Dipole-dipole bonds. 


Synthesis of hydrogen chloride covalent compound:Usually this covalent hydrogen chloride is synthesized on the basis of industrial scale, which is used in the production of hydrochloric acid. Hydrogen chloride is synthesized using some methods, few of them are as follows1)Direct synthesis:In industries like chloro-alkali industry, hydrogen chloride is produced by electrolyzing the brine solution ( NaCl+H2O) which produces chlorine gas, sodium chloride and hydrogen. The obtained chlorine gas combines with hydrogen and gives covalent hydrogen chloride. This reaction is exothermic due to the liberation of heat. 


 The reaction is as follows,2NaCl + 2H2O="=="> 2NaOH+ H2+Cl2Cl2 + H2 → 2HCl2)Organic synthesis:There are two types in this method, they area)Halogenated organic compounds are treated with some acids like HF, hydrogen chloride is formed.R-Cl + HF ===> HCl + RF.b)Hydrocarbons are treated with chlorine gas, hydrogen chloride is formed.R-H + Cl2="=="> H-Cl + R-Cl.3)Laboratory synthesis:In this method hydrogen chloride is synthesized by the reaction between sodium chloride and sulphuric acid.NaCl + H2SO4="=="> HCl+NaHSO4This reaction takes place at room temperature. At 200˚C, the remaining salt can proceed the reaction as followsNaCl + NaHSO4 ===> HCl+ Na2SO4.Applications of covalently bonded hydrogen chloride.There are many applications of hydrogen chloride, few of them are as followsUsed in the hydrochloric acid production.Used in the production of alkyl halides like vinyl chloride. Methyl chloride.Used to generate chloride based Lewis acid in labs.