Chapter 5, Problem 5.28P

Interpretation Introduction

Interpretation:

The protonation reaction for given nicotine base and the corresponding deprotonation reaction of conjugate acid and also the $\text{p}{\text{K}}_{\text{a}}$ value for nicotine has to be determined.

Concept Introduction:

Acid dissociation constant ${\text{K}}_{\text{a}}$ represents how strong the acid is in a solution.

$\text{p}{\text{K}}_{\text{a}}=-\text{log}{\text{K}}_{\text{a}}$

The strength of acid decreases as the value of $\text{p}{\text{K}}_{\text{a}}$ increases

Ionic-product constant for water: It is the hydronium ion concentration times the $\text{O}{\text{H}}^{-}$ concentration present in the solution.

$\begin{array}{l}{\text{H}}_2{\text{O}}_{\left(\text{l}\right)}+{\text{H}}_2{\text{O}}_{\left(\text{l}\right)}{\text{H}}_3{\text{O}}^{+}{}_{\left(\text{a}\text{q}\right)}+\text{O}{\text{H}}^{-}{}_{\left(\text{a}\text{q}\right)}\\ \\ \text{K}=\frac{\left[{\text{H}}_3{\text{O}}^{+}\right]\left[\text{O}{\text{H}}^{-}\right]}{\left[{\text{H}}_2\text{O}\right]\left[{\text{H}}_2\text{O}\right]}\\ \\ \left[{\text{H}}_3{\text{O}}^{+}\right]=\left[\text{O}{\text{H}}^{-}\right]=1.00\times {10}^{-7}\text{M}\\ \\ \therefore {\text{K}}_{\text{W}}=\text{K}\left[{\text{H}}_2\text{O}\right]\left[{\text{H}}_2\text{O}\right]=\left[{\text{H}}_3{\text{O}}^{+}\right]\left[\text{O}{\text{H}}^{-}\right]\\ \\ {\text{K}}_{\text{W}}=1.00\times {10}^{-14}\text{M}\end{array}$