Chapter 7, Problem 131AE

Interpretation Introduction

Interpretation: The salt which is present in the given solution with concentration of 1.0 M and pH shown as 4.6 needs to be identified.

  ${\text{HCl, NaOH, NH4Cl, HCN, NH}}_{\text{3}}\text{, HF, NaCN}$

Concept Introduction: A base is the substance that gives ${\text{OH}}^{\text{-}}$ ions in its aqueous solution. On the basis of base dissociation, they can be classified as strong and weak base. On the contrary, a weak base ionized partially and reaches to equilibrium.

  ${\text{BOH}}_{\text{(aq)}}\rightleftharpoons {\text{OH}}^{\text{-}}{}_{\text{(aq)}}{\text{+B}}^{\text{-}}{}_{\text{(aq)}}$

The base dissociation constant is the ratio of concentration of product and reactant for the equilibrium reaction of weak base in solution. For the given weak base BOH, it can be written as:

  $\begin{array}{l}{\text{BOH}}_{\text{(aq)}}\rightleftharpoons {\text{OH}}^{\text{-}}{}_{\text{(aq)}}{\text{+ B}}^{+}{}_{\text{(aq)}}\\ {\text{K}}_{\text{b}}\text{=}\frac{{\text{[OH}}^{\text{-}}{\text{] [B}}^{+}\text{]}}{\text{[BOH]}}\end{array}$