Hydrosulfuric acid, commonly known as hydrogen sulfide (H2S), is classified as a weak acid. This classification is based on its ability to partially dissociate in water, releasing hydrogen ions (H+) into the solution.
When we write hydrosulfuric acid in its aqueous form, it is represented as H2S(aq). This indicates that the acid is dissolved in water. In an aqueous solution, hydrosulfuric acid does not completely ionize; instead, it establishes an equilibrium between the undissociated molecules and the ions produced:
H2S(aq) ⇌ H+(aq) + HS–(aq)
Due to this partial dissociation, the overall pH of the solution remains higher compared to that of a strong acid, which fully dissociates. In conclusion, hydrosulfuric acid is a weak acid, and in aqueous solution, it is represented as H2S(aq).