What Is An Acid?

Acids are those compounds or chemicals which contain H⁺ Ions in them. Acids when dissolved in aqueous i.e water dissociates as H⁺ ions and Cl^- ions. These H⁺ ions are very unstable so combine with water molecule i.e

H₂O + H⁺ = H₃O⁺

These H⁺ ions can be detected only using pH paper or litmus paper. These papers change colour i.e blue litmus change into red color when they come in contact with H⁺ ions. This proves the presence of H+ ions in the given solutions and the given compound is therefore called as an acid.