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Is hcl Ionic or Covalent

May 6, 2013

Introduction to HCl

In Middle ages, HCl (Hydro Chloric acid) was found to release its vapors, known as Marine Acid air. In the 17th century, Johann Rudolf Glauber reacted NaCl (Sodium Chloride salt) and H2SO4 (Hydrogen Sulphate) together and they found the vapors of HCl gas coming. In 1772, Carl Wilhelm Scheele again performed the same reaction (NaCl + H2SO4) and they were credited for the discovery of HCl. Again, another scientist named Joseph priestly and Humphry Davy prepared HCl in 1772 and 1810.

About HCl

A chemical compound named Hydrogen Chloride having molecular formula as HCl composed of Hydrogen and Chlorine. HCl is generally a gas at room temperatures and in case of humidity; HCl gas forms white fumes of HCl acid. HCl gas has hydrogen and Chlorine in it, which are two diatomic molecules. Moreover, they both are covalently bonded in HCl. Due to the high electro negativity of Chlorine the covalent bond in HCl becomes polar. In HCl there is a partial negative charge on Chlorine (due to its electro negativity) and partial positive charge on Hydrogen , this entirely makes a large dipole moment in HCl. Due to this high polarity in HCl it is quiet easily soluble in water.

Ionic or Covalent Character of HCl

As it has been, find that HCl has a large dipole moment in it due to the presence of its high polarity, it is polar covalent molecule. HCl is soluble in polar solvent like water, due to the presence of polarity in it (as “Likes dissolves like”). That is why when HCl is mixed in water then it forms Hydronium ions (H3O+) and Chloride ion (Cl), as the reaction showing this is as follows:

  •         HCl  +  H2O  a `->`   H3O+   +  Cl

This resulting solution produces a strong acid, i.e. Hydrochloric acid.

  • When calculated the ionization constant of HCl (Ka) is found to be very large , which shows that HCl will be completely dissociated and ionized also.
  • Due to its polarity HCl is able to get dissolved in other ionic or polar covalent solvents like Methanol.

Bonds in HCL

Hydrogen Chloride is a chemical compound with molecular formula as HCl. Hydrogen Chloride is composed of Hydrogen and Chlorine atoms. The bonding in Hydrogen Chloride is covalent, but due to the high electro negativity tendency of Chlorine the bonding becomes polar covalent in nature. Hydrogen Chloride easily reacts with bases and other ionic compounds. On being dissolved in water Hydrogen Chloride gets separated in H+ and Cl ions. In water, hydrogen Chloride gives its acid. The direct synthesis of Hydrogen Chloride can also be observed and Chlorine gas gets attached to Hydrogen atoms in the presence of heat to produce hydrogen chloride.

Polarity of Hydrogen Chloride

As it has been said, earlier that Hydrogen Chloride is composed of two diatomic atoms one is Hydrogen and the other is Chlorine. The Chlorine atom is much more electronegative than Hydrogen atom, that is why Hydrogen gains positive charge (partially), and Chlorine atom gains negative charge (partially). Due to the difference in their values of electro negativity hydrogen and Chlorine forms a dipole (an arrangement of pair of atoms having opposite charges). In addition, due to this Hydrogen Chloride develops a Polar covalent bond in it. Many reactions have shown that Hydrogen Chloride is polar in nature because the Hydrogen and Chlorine atoms get easily separated when mixed in solution having dipoles.


HCl can be directly prepared in industrial processes and this HCl is mainly used for the production of HCl acid and it is done by the direct combination of Chlorine gas and Hydrogen gas under some specific conditions. As HCl is also used in some small industrial purposes as a reagent and also in purification.


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