Is H2CO3 a Strong or Weak Acid? Explain.

Carbonic acid (H₂CO₃) is classified as a weak acid. This classification stems from its incomplete dissociation in water. When carbonic acid dissolves, it partially dissociates into hydrogen ions (H⁺) and bicarbonate ions (HCO₃^–), but not all of the H₂CO₃ molecules break apart.

In contrast, strong acids, such as hydrochloric acid (HCl), fully dissociate in solution, releasing all of their hydrogen ions. This full dissociation leads to a high concentration of H⁺ ions, resulting in a lower pH. Since carbonic acid does not completely ionize, it produces a relatively lower concentration of H⁺ ions, hence a higher pH compared to strong acids.

Moreover, H₂CO₃ exists in equilibrium with its dissociated forms. The equilibrium reaction can be represented as follows:

H₂CO₃ ⇌ H⁺ + HCO₃^–

This dynamic equilibrium illustrates that the dissociation is not complete, reinforcing the fact that H₂CO₃ is a weak acid.