Hydrochloric Acid (HCl)

Once hydrogen chloride gets dissolved in water, HCl is created. It is an unsophisticated diatomic molecule. The hydrogen and chlorine atom are joined with a single covalent bond. The bond is polar because chlorine is more electronegative than hydrogen.

It is highly acidic, colorless, and viscous. It is corrosive and has a uniquely bitter smell. It is usually used as a laboratory reagent, and in industry, it produces leather and gelatin. The physical assets such as density, melting point, pH, and boiling point rely on the concentration of HCl.

Hydrochloric Acid Preparation

In both laboratories and industrial settings, hydrogen chloride is produced by heating sodium chloride with concentrated H₂SO₄. The gas can be dried by passing it through concentrated sulfuric acid.

Reactions:

NaCl+H2SO4→NaHSO4+HClNaCl + H_2SO_4 \rightarrow NaHSO_4 + HClNaCl+H2​SO4​→NaHSO4​+HCl NaHSO4+NaCl→Na2SO4+HClNaHSO_4 + NaCl \rightarrow Na_2SO_4 + HClNaHSO4​+NaCl→Na2​SO4​+HCl

Hydrochloric Acid Properties

• Hydrogen chloride is a very odorous and colorless gas.

• Gaseous hydrogen chloride reacts with the chlorides formed by active metals and their oxides, hydroxides, and carbonates. These reactions only happen willingly in the presence of humidity.

• Hydrochloric acid reactions are similar to those of common strong acids. For example:

  • Metal reactions in which hydrogen gas is relocated

  • Reactions with weak acid salts where the heavy acid gets displaced

Wikipedia contributors. (n.d.). Hydrochloric acid. In Wikipedia. Retrieved August 16, 2025, from https://en.wikipedia.org/wiki/Hydrochloric_acid