Chapter 12, Problem 12.11P

Interpretation Introduction

Interpretation:

Activity of ${\left({\text{C}}_3{\text{H}}_7\right)}_4{\text{N}}^{+}$ ion for a solution that has $\text{0}\text{.0050 M }{\left({\text{C}}_3{\text{H}}_7\right)}_4{\text{N}}^{+}{\text{Br}}^{-}$ and  $\text{0}\text{.0050 M }{\left({\text{C}}_3{\text{H}}_7\right)}_4{\text{N}}^{+}{\text{Cl}}^{-}$ has to be calculated.

Concept Introduction:

Extended Debye Huckel law quantifies activity coefficient in terms of ionic strength and hydrated size as follows:

  $\log \text{γ}=\frac{-0.51z^2\sqrt{\text{μ}}}{1+\left(\text{α}\sqrt{\text{μ}}\text{/}305\right)}$

Here

$z$ denotes charge.

$\text{μ}$ denotes ionic strength.

$\text{γ}$ denotes activity coefficient.

$\text{α}$ denotes ionic size.

To account for charged ionic atmosphere of various species concentration terms include concept of activities. Activity is defined as product of concentration times the activity coefficient. Thus expression of activity is written as follows:

  $\text{Activity}=\left[\text{C}\right]\cdot \text{γ}$