Chapter 16, Problem 32A

(a)

Interpretation Introduction

Interpretation:

pH of the solution having $\text{pOH = 3}\text{.75}$ should be calculated and whether the solution is acidic, basic or neutral is to be indicated.

Concept Introduction:

The acidity or alkalinity of a solution is expressed by determining $\text{pH}$ of the solution. $\text{pH}$ of a solution is defined as negative logarithm of the concentration of ${\text{H}}^{\text{+}}$ ion in the solution. $\text{pH}$ is expressed as-

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

  $\text{pOH}$ of a solution is defined as negative logarithm of the concentration of hydroxyl ion $\left[{\text{OH}}^{\text{-}}\right]$ in the solution. $\text{pOH}$ is expressed as-

  $\text{pOH}=-\mathrm{l}\mathrm{o}\mathrm{g}[\mathrm{O}{\mathrm{H}}^{-}]$

Both $\text{pH}$ and $\text{pOH}$ are related to each other by this following equation-

  $\text{pH}\text{+}\text{pOH=}{\text{pK}}_{\text{w}}$

At 25 °C the value of ${\text{pK}}_{\text{w}}$ is 14. ${\text{pK}}_{\text{w}}$ can be expressed as-

  ${\text{pK}}_{\text{w}}=-\mathrm{l}\mathrm{o}\mathrm{g}{\mathrm{K}}_{\mathrm{w}}$

Where, ${\mathrm{K}}_{\mathrm{w}}=[{\mathrm{H}}^{+}]\times [\mathrm{O}{\mathrm{H}}^{-}]$ and at $25°\text{C}$ the value of ${\text{K}}_{\text{w}}$ is ${10}^{-14}$ .

Answer to Problem 32A

The $\mathrm{p}\mathrm{H}$ of the solution is $10.25$ and the solution is basic.

Explanation of Solution

Using the following equation to calculate $\mathrm{p}\mathrm{H}$ value of the solution,

  $\text{pH}\text{+}\text{pOH=}{\text{pK}}_{\text{w}}\text{=}\text{14}$

So,

  $\begin{array}{l}\text{pH}\text{=}\text{14}\text{-}\text{pOH}\\ =14-3.75\\ =10.25\end{array}$

The solution having pH less than 7 is acidic in nature, pH equal to 7 means the solution is neutral and pH greater than 7 means the solution is basic in nature.

  $\mathrm{p}\mathrm{H}$ of the solution is $10.25$ and thus the solution is basic.

(b)

Interpretation Introduction

Interpretation:

pH of the solution having $\text{pOH = 2}\text{.38}$ should be calculated and whether the solution is acidic, basic or neutral is to be indicated.

Concept Introduction:

The acidity or alkalinity of a solution is expressed by determining $\text{pH}$ of the solution. $\text{pH}$ of a solution is defined as negative logarithm of the concentration of ${\text{H}}^{\text{+}}$ ion in the solution. $\text{pH}$ is expressed as-

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

$\text{pOH}$ of a solution is defined as negative logarithm of the concentration of hydroxyl ion $\left[{\text{OH}}^{\text{-}}\right]$ in the solution. $\text{pOH}$ is expressed as-

  $\text{pOH}=-\mathrm{l}\mathrm{o}\mathrm{g}[\mathrm{O}{\mathrm{H}}^{-}]$

Both $\text{pH}$ and $\text{pOH}$ are related to each other by this following equation-

  $\text{pH}\text{+}\text{pOH=}{\text{pK}}_{\text{w}}$

At 25 °C the value of ${\text{pK}}_{\text{w}}$ is 14. ${\text{pK}}_{\text{w}}$ can be expressed as-

  ${\text{pK}}_{\text{w}}=-\mathrm{l}\mathrm{o}\mathrm{g}{\mathrm{K}}_{\mathrm{w}}$

Where, ${\mathrm{K}}_{\mathrm{w}}=[{\mathrm{H}}^{+}]\times [\mathrm{O}{\mathrm{H}}^{-}]$ and at $25°\text{C}$ the value of ${\text{K}}_{\text{w}}$ is ${10}^{-14}$ .

Answer to Problem 32A

The $\mathrm{p}\mathrm{H}$ of the solution is $11.62$ and the solution is basic.

Explanation of Solution

Using the following equation to calculate $\mathrm{p}\mathrm{H}$ value of the solution,

  $\text{pH}\text{+}\text{pOH=}{\text{pK}}_{\text{w}}\text{=}\text{14}$

So,

  $\begin{array}{l}\text{pH}\text{=}\text{14}\text{-}\text{pOH}\\ =14-2.38\\ =11.62\end{array}$

The solution having pH less than 7 is acidic in nature, pH equal to 7 means the solution is neutral and pH greater than 7 means the solution is basic in nature.

  $\mathrm{p}\mathrm{H}$ of the solution is $11.62$ and thus the solution is basic.

(c)

Interpretation Introduction

Interpretation:

pH of the solution having $\text{pOH = 11}\text{.61}$ should be calculated and whether the solution is acidic, basic or neutral is to be indicated.

Concept Introduction:

The acidity or alkalinity of a solution is expressed by determining $\text{pH}$ of the solution. $\text{pH}$ of a solution is defined as negative logarithm of the concentration of ${\text{H}}^{\text{+}}$ ion in the solution. $\text{pH}$ is expressed as-

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

$\text{pOH}$ of a solution is defined as negative logarithm of the concentration of hydroxyl ion $\left[{\text{OH}}^{\text{-}}\right]$ in the solution. $\text{pOH}$ is expressed as-

  $\text{pOH}=-\mathrm{l}\mathrm{o}\mathrm{g}[\mathrm{O}{\mathrm{H}}^{-}]$

Both $\text{pH}$ and $\text{pOH}$ are related to each other by this following equation-

  $\text{pH}\text{+}\text{pOH=}{\text{pK}}_{\text{w}}$

At 25 °C the value of ${\text{pK}}_{\text{w}}$ is 14. ${\text{pK}}_{\text{w}}$ can be expressed as-

  ${\text{pK}}_{\text{w}}=-\mathrm{l}\mathrm{o}\mathrm{g}{\mathrm{K}}_{\mathrm{w}}$

Where, ${\mathrm{K}}_{\mathrm{w}}=[{\mathrm{H}}^{+}]\times [\mathrm{O}{\mathrm{H}}^{-}]$ and at $25°\text{C}$ the value of ${\text{K}}_{\text{w}}$ is ${10}^{-14}$ .

Answer to Problem 32A

The $\mathrm{p}\mathrm{H}$ of the solution is $2.39$ and the solution is acidic.

Explanation of Solution

Using the following equation to calculate $\mathrm{p}\mathrm{H}$ value of the solution,

  $\text{pH}\text{+}\text{pOH=}{\text{pK}}_{\text{w}}\text{=}\text{14}$

So,

  $\begin{array}{l}\text{pH}\text{=}\text{14}\text{-}\text{pOH}\\ =14-11.61\\ =2.39\end{array}$

The solution having pH less than 7 is acidic in nature, pH equal to 7 means the solution is neutral and pH greater than 7 means the solution is basic in nature.

  $\mathrm{p}\mathrm{H}$ of the solution is $2.39$ and thus the solution is acidic.

(d)

Interpretation Introduction

Interpretation:

pH of the solution having $\text{pOH = 9}\text{.44}$ should be calculated and whether the solution is acidic, basic or neutral is to be indicated.

Concept Introduction:

The acidity or alkalinity of a solution is expressed by determining $\text{pH}$ of the solution. $\text{pH}$ of a solution is defined as negative logarithm of the concentration of ${\text{H}}^{\text{+}}$ ion in the solution. $\text{pH}$ is expressed as-

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

  $\text{pOH}$ of a solution is defined as negative logarithm of the concentration of hydroxyl ion $\left[{\text{OH}}^{\text{-}}\right]$ in the solution. $\text{pOH}$ is expressed as-

  $\text{pOH}=-\mathrm{l}\mathrm{o}\mathrm{g}[\mathrm{O}{\mathrm{H}}^{-}]$

Both $\text{pH}$ and $\text{pOH}$ are related to each other by this following equation-

  $\text{pH}\text{+}\text{pOH=}{\text{pK}}_{\text{w}}$

At 25 °C the value of ${\text{pK}}_{\text{w}}$ is 14. ${\text{pK}}_{\text{w}}$ can be expressed as-

  ${\text{pK}}_{\text{w}}=-\mathrm{l}\mathrm{o}\mathrm{g}{\mathrm{K}}_{\mathrm{w}}$

Where, ${\mathrm{K}}_{\mathrm{w}}=[{\mathrm{H}}^{+}]\times [\mathrm{O}{\mathrm{H}}^{-}]$ and at $25°\text{C}$ the value of ${\text{K}}_{\text{w}}$ is ${10}^{-14}$ .

Answer to Problem 32A

The $\mathrm{p}\mathrm{H}$ of the solution is $4.56$ and the solution is acidic.

Explanation of Solution

Using the following equation to calculate $\mathrm{p}\mathrm{H}$ value of the solution,

  $\text{pH}\text{+}\text{pOH=}{\text{pK}}_{\text{w}}\text{=}\text{14}$

So,

  $\begin{array}{l}\text{pH}\text{=}\text{14}\text{-}\text{pOH}\\ \text{=}\text{14}\text{-}\text{9}\text{.44}\\ \text{=}\text{4}\text{.56}\end{array}$

The solution having pH less than 7 is acidic in nature, pH equal to 7 means the solution is neutral and pH greater than 7 means the solution is basic in nature.

  $\mathrm{p}\mathrm{H}$ of the solution is $4.56$ and thus the solution is acidic.