Chapter 18.2, Problem 18.3BFP

Interpretation Introduction

Interpretation: In the given molecular model, an aqueous solution of two conjugate acid-base pairs $\text{HC}$ / ${\text{C}}^{\text{-}}$ and $\text{HD}$ / $\text{D}$ is depicted. It is given that HD is a stronger acid than HC. The colors of the conjugate bases $\text{D}$ and ${\text{C}}^{\text{-}}$ in the given molecular model must be identified. The value of the equilibrium constant ${\text{K}}_{\text{c}}$ is also to be determined.

Concept introduction: Strong acid can donate its proton. Strong acid/base will have weaker conjugate base/acid. The equilibrium constant ${\text{K}}_{\text{c}}$ represents the ratio of concentrations of the product to the reactants. When a strong acid and base react to give a weak acid and base, then the ${\text{K}}_{\text{c}}$ value will be greater than 1. The reaction will go forward in the direction of a stronger acid/base to a weaker acid/ base.