1. Acids Donate Protons (H⁺): Acids are substances that donate protons (H⁺) when dissolved in water. For example, hydrochloric acid (HCl) dissociates into H⁺ and Cl⁻ ions in water.
2. Water Acts as a Base: Water molecules can act as a base, accepting protons. The lone pairs of electrons on the oxygen atom in water are available to form a bond with a proton.
3. Formation of Hydronium Ions: When an acid molecule donates a proton to a water molecule, a hydronium ion (H₃O⁺) is formed. This is a reversible reaction, but the equilibrium typically favors the formation of hydronium ions in acidic solutions.
Simplified Equation:
```
HCl(aq) + H₂O(l) ⇌ H₃O⁺(aq) + Cl⁻(aq)
```
In essence:
* Acids release protons (H⁺).
* Water accepts these protons, forming hydronium ions (H₃O⁺).
The presence of hydronium ions is what defines an acidic solution. The higher the concentration of hydronium ions, the stronger the acidic nature of the solution.
