Chapter 17, Problem 17.1P

Write a balanced net ionic equation for the neutralization of equimolar amounts of $HN{O}_2$ and KOH.
Indicate whether the pH after neutralization is greater than, equal to, or less than 7. Values of $K_a$ and $K_B$ are listed in Appendix C.

Interpretation Introduction

Interpretation:

A balance net ionic equation for the neutralization of equimolar amount of ${\text{HNO}}_{\text{2}}$ and KOH needs to be determined, if the pH after neutralization is greater than, equal to or less than 7 needs to be determined.

Concept introduction:

In the balance equation number of atoms of particular element i.e reactant is equals to number of atoms of that element as a product.

pH is a measure of hydrogen ion concentration. It expresses the acidity and basicity of a solution.

Answer to Problem 17.1P

${\text{HNO}}_{\text{2}}\left(aq\right)+{\text{OH}}^{-}\left(aq\right)\to {\text{NO}}_{\text{2}}{}^{-}\left(aq\right)+{\text{H}}_{\text{2}}\text{O}\left(l\right)$

After neutralization, pH is greater than 7 for the given equation.

Explanation of Solution

${\text{HNO}}_{\text{2}}$ is a week acid and KOH is a strong base. The balance net ionic equation for the neutralization of equimolar amounts of ${\text{HNO}}_{\text{2}}$ and KOH is as follows:

${\text{HNO}}_{\text{2}}\left(aq\right)+{\text{OH}}^{-}\left(aq\right)\to {\text{NO}}_{\text{2}}{}^{-}\left(aq\right)+{\text{H}}_{\text{2}}\text{O}\left(l\right)$

The solution contains ${\text{NO}}_2{}^{-}$ weak base and ${\text{K}}^{\text{+}}$ ion after neutralization. Thus pH is greater than 7.

Conclusion

Thus, the balanced chemical equation is as follows:

${\text{HNO}}_{\text{2}}\left(aq\right)+{\text{OH}}^{-}\left(aq\right)\to {\text{NO}}_{\text{2}}{}^{-}\left(aq\right)+{\text{H}}_{\text{2}}\text{O}\left(l\right)$

After neutralization, pH is greater than 7 for the given equation.