Question

Please be thorough and do all the steps with equations used! Thank you! Calculate Ka for the cation and Kb for the anion in an aqueous NH4NO2 solution.

Answer 1

NH4NO2 is a salt formed by the reaction of base NH4OH and an acid HNO2, both the acid and base is weak in nature.

NH4OH + HNO2 = NH4NO2 + H2O

Now in aqueous solution, this salt gets hydrolyzed. the main reason for hydrolysis of this salt is that the conjugate ions are coming from weak acid and base so both the conjugate ions are strong base and acid respectively. so it will react with water, or hydrolyse with water to form respective acid or base.

NH₄⁺ + H₂O < = > NH₄OH + H⁺

On the other hand the NO2 - ion also hydrolysed by water to form HNO2

NO₂^- + H2O < => HNO₂ + OH^-

now,

Ka of NH4⁺ = [NH4OH] [H+] / [NH4+]

AND Kb Of NO2- is = [HNO2][OH-]/ [NO2]