Chapter 19, Problem 5STP

Interpretation Introduction

Interpretation : The pH of the solution is to be calculated.

Concept Introduction : The negative logarithm of the concentration of hydrogen ions is the pH of a solution. The formula to calculate pH is given as

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

Answer to Problem 5STP

Correct answer: Option (C)

Explanation of Solution

Reason for correct option:

The concentration of hydrogen ions is $2.3\times {10}^{-8}\text{M}$ .

The formula to calculate pH is given as

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

To calculate the pH of the solution, substitute the values in the above formula:

  $\begin{array}{c}\text{pH=}-{\text{log[H}}^{\text{+}}\text{]}\\ \text{=}-\log \left(2.3\times {10}^{-8}\right)\\ \text{pH}=7.63\end{array}$

Since option C is in the range between 7 and 8, it is the correct answer.

So, option (C) is the correct answer.

Conclusion

Reasons for incorrect options:

Option (A), (B), (D): All these options are irrelevant since the pH is not in these ranges.