* Equilibrium: NH₃ reacts with water to form ammonium ions (NH₄⁺) and hydroxide ions (OH⁻):
```
NH₃(aq) + H₂O(l) ⇌ NH₄⁺(aq) + OH⁻(aq)
```
This reaction reaches an equilibrium, meaning it doesn't go to completion. A significant amount of NH₃ remains undissociated in solution.
* Low Ionization Constant: The equilibrium constant for this reaction, called the base ionization constant (Kb), is relatively small (Kb = 1.8 x 10⁻⁵). This indicates that the equilibrium favors the reactants (NH₃ and H₂O) over the products (NH₄⁺ and OH⁻), meaning only a small percentage of NH₃ molecules ionize.
* Weak Base: Ammonia acts as a weak base because it accepts protons (H⁺) from water, but it does so to a limited extent. This limited proton acceptance leads to low conductivity.
In contrast, strong electrolytes like strong acids and strong bases completely ionize in solution, resulting in high conductivity.
Key Takeaways:
* Weak electrolytes like ammonia ionize partially, resulting in a lower concentration of ions and lower conductivity.
* The equilibrium constant for ionization is relatively small, indicating a preference for the non-ionized form.
* Weak electrolytes are typically weak acids or weak bases.
