Effect of Cation and Anion in Solution

To determine whether a salt forms an acidic, a basic, or a neutral solution when dissolved in water, we must consider the action of both cation and anion. There are four possible combinations. 

if the salt contains an anion that does not react with water and a cation that does not react with water, we expect the pH to be neutral. Such is the case when the anion is a conjugate base of a strong acid and the cation is either from group lA or one of the heavier members of group 2A (Ca, Sr, and Ba ). Examples NaCl, Ba(N03)2, RbC104. 

If the salt contains an anion and a cation both capable of reacting with water, both hydroxide ions and hydronium ions are produced. Whether the solution is basic, neutral, or acidic depends on the relative abilities of the ions to react with water. Examples NH4CIO, Al(CH3COO)3, Crp3. 

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