When hydrochloric acid (HCl) reacts with water (H2O), it dissociates into hydrogen ions (H+) and chloride ions (Cl-). This is because hydrochloric acid is a strong acid.
The Dissociation Process Explained
- Hydrochloric Acid is a Strong Acid: This means that it readily donates its proton (H+) to water.
- Dissociation: The HCl molecule breaks apart into its constituent ions:
HCl (aq) → H+ (aq) + Cl- (aq) - Hydronium Ion Formation: The hydrogen ion (H+) is highly reactive and immediately bonds with a water molecule to form a hydronium ion (H3O+). This is a more accurate representation of the hydrogen ion's state in aqueous solution:
H+ (aq) + H2O (l) → H3O+ (aq)
Simplified Equation
Often, the reaction is represented as:
HCl (aq) + H2O (l) → H3O+ (aq) + Cl- (aq)
However, for simplicity, the hydronium ion is often represented as just H+.
Consequences of the Reaction
The formation of H3O+ ions (or simply H+) is what makes the solution acidic. The higher the concentration of H3O+ ions, the lower the pH and the stronger the acidity of the solution. Chloride ions (Cl-) remain dissolved in the water.
Summary
Hydrochloric acid reacts with water by dissociating into hydronium ions and chloride ions, resulting in an acidic solution.
