2. Bases Properties and Examples

Salts of weak bases and weak acids

Salt solutions containing acidic cations and basic anions such as NH4F (ammonium fluoride) have two possible reactions:NH4+(aq) + H2O(l) ↔ H3O+(aq) + NH3(aq)           Ka(NH4+) = 5.6 x 10-10F(aq) + H2O(l) ↔ HF(aq) + OH(aq)                   Kb(F) = 1.4 x 10-11

Since Ka(NH4+) > Kb (F), the reaction of ammonia with water is more favorable. Therefore, the resulting solution is slightly acidic.

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