Chapter 16, Problem 30A

(a)

Interpretation Introduction

Interpretation:

The $\text{pH}$ of the solution having $[{\mathrm{H}}^{+}]=4.02\times {10}^{-3}\mathrm{M}$ has to be calculated and whether the solution is acidic or basic has 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-

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

Answer to Problem 30A

The $\text{pH}$ of the solution is $2.396$ and the solution is acidic.

Explanation of Solution

The pH of the solution is calculated as:

  $\begin{array}{l}\text{pH}=-\mathrm{l}\mathrm{o}\mathrm{g}[{\mathrm{H}}^{+}]\\ =-\mathrm{l}\mathrm{o}\mathrm{g}[4.02\mathrm{}\times \mathrm{}10^{-3}]\\ =2.396\end{array}$

Hence, $\text{pH}$ of the solution is $2.396$ .

Since, the pH of the solution is less than 7 so, the solution is acidic.

(b)

Interpretation Introduction

Interpretation:

The $\text{pH}$ of the solution having $[{\mathrm{H}}^{+}]=\text{ 8}\text{.99 }\times {10}^{-7}\mathrm{M}$ has to be calculated and whether the solution is acidic or basic has 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-

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

Answer to Problem 30A

The $\mathrm{p}\mathrm{H}$ of the solution is $6.046$ and the solution is slightly acidic.

Explanation of Solution

The pH of the solution is calculated as:

  $\begin{array}{l}\text{pH}\text{=}\text{-}{\text{log[H}}^{\text{+}}\text{]}\\ \text{=}\text{-}\text{log[8}\text{.99}\text{×}{\text{10}}^{\text{-7}}\text{]}\\ \text{=}\text{6}\text{.046}\end{array}$

Hence, $\mathrm{p}\mathrm{H}$ of the solution is $6.046$ .

Since, the pH of the solution is less than 7 so, the solution is acidic.

(c)

Interpretation Introduction

Interpretation:

The $\text{pH}$ of the solution having $[{\mathrm{H}}^{+}]=2.39\times {10}^{-6}\mathrm{M}$ has to be calculated and whether the solution is acidic or basic has 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-

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

Answer to Problem 30A

The $\text{pH}$ of the solution is $5.621$ and the solution is acidic.

Explanation of Solution

The pH of the solution is calculated as:

  $\begin{array}{l}\text{pH}\text{=}\text{-}{\text{log[H}}^{\text{+}}\text{]}\\ \text{=}\text{-}\text{log[2}{\text{.39 × 10}}^{\text{-6}}\text{]}\\ \text{=}\text{5}\text{.621}\end{array}$

Hence, $\text{pH}$ of the solution is $5.621$ .

Since, the pH of the solution is less than 7 so, the solution is acidic.

(d)

Interpretation Introduction

Interpretation:

The $\text{pH}$ of the solution having $[{\mathrm{H}}^{+}]=1.89\times {10}^{-10}\mathrm{M}$ has to be calculated and whether the solution is acidic or basic has 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-

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

Answer to Problem 30A

The $\text{pH}$ of the solution is $9.723$ and the solution is basic.

Explanation of Solution

The pH of the solution is calculated as:

  $\begin{array}{l}\text{pH}\text{=}\text{-}{\text{log[H}}^{\text{+}}\text{]}\\ \text{=}\text{-}\text{log[1}\text{.89}\text{×}{\text{10}}^{\text{-10}}\text{]}\\ \text{=}\text{9}\text{.723}\end{array}$

Hence, $\text{pH}$ of the solution is $9.723$ .

Since, the pH of the solution is less than 7 so, the solution is acidic.