Chapter 15, Problem 15.21P

Interpretation Introduction

Interpretation:

Value of $E$ and percent increase in $\left[{\text{Ca}}^{2+}\right]$ required to get same voltage has to be calculated.

Concept Introduction:

Potential difference with selectivity coefficient included is evaluated by expression as follows:

  $E=\text{constant}+\text{β}\frac{\left(0.05916\right)}{2}\log \left(\left[{\text{Ca}}^{2+}\right]+k_{{\text{Ca}}^{2+},{\text{ Mg}}^{2+}}\left[{\text{Mg}}^{2+}\right]\right)$

Here,

$\text{β}$ is constant with value unity for most electrodes.

$k_{{\text{Ca}}^{2+},{\text{ Mg}}^{2+}}$ denotes selectivity coefficient.

$\left[{\text{Ca}}^{2+}\right]$ denotes concentration of ${\text{Ca}}^{2+}$ analyte solution.

$\left[{\text{Mg}}^{2+}\right]$ denotes concentration of ${\text{Mg}}^{2+}$ solution.

$E$ denotes potential difference.