Chapter 15.4, Problem 6PE

Interpretation Introduction

Interpretation: The $\text{pH}$ of the given $\text{Ba}{\left(\text{OH}\right)}_{\text{2}}$ solution has to be calculated.

Concept Introduction:

$pH$ calculation:

$\text{pH}$ is the negative logarithm of concentration of ${\text{H}}^{\text{+}}$ ion in a solution.

It can be expressed as

$\text{pH}\text{=}-\log \left[{\text{H}}^{\text{+}}\right]$

$\text{pH}$ can be calculated from the relation between $\text{pH}$ and $\text{pOH}$ as shown below:

$\begin{array}{l}\text{pH}\text{+}\text{pOH}\text{=}\text{14}\\ \text{pH}\text{=}\text{14}\text{-}\text{pOH}\end{array}$

$\text{pOH}$ is the negative logarithm of concentration of ${\text{OH}}^{-}$ ion in a solution.

It can be expressed as

$\text{pOH}\text{=}-\log \left[{\text{OH}}^{-}\right]$

The concentration of the ${\text{H}}^{\text{+}}$ and ${\text{OH}}^{-}$ in the given concentration of a solution can be calculated using ICE table:

ICE table is used to determine the equilibrium concentration of any chemical species under dynamic equilibrium. ICE is the abbreviation of the words “Initial Change and Equilibrium”. The ICE table tabulates the following criteria:

• Initial concentration
• Change in the concentration
• Concentration at equilibrium or final concentration.

The equilibrium concentration of any species has to be taken into concentration for its concentration in calculation.

The model for an ICE table is shown below:

The equation is:                                      $\text{A}$            $+$          $\text{B}$        $\stackrel{}{\rightleftharpoons }$      $\text{AB}$
$\begin{array}{l}\text{Initial}\text{Concentration}\\ \left(\text{in}\text{mol/M}\right)\end{array}$	Some value	Some value	0
$\begin{array}{l}\text{Change}\text{in}\text{Concentration}\\ \left(\text{in}\text{mol/M}\right)\end{array}$	-x	-x	+x
$\begin{array}{l}\text{Concentration at equilibrium}\\ \left(\text{in}\text{mol/M}\right)\end{array}$	Some value -x	Some value -x	0 +x

Where,

1. A- Reactant
2. B- Another Reactant

AB- Product.

x- change in the concentration.

The -ve sign of x represents the decrease in the concentration whereas +ve sign of x represents the increase in the concentration.