Chapter 16, Problem 17A

Interpretation Introduction

Interpretation: Strength of conjugate bases for given acids has to be determined.

Concept introduction: A very simple definition of acid is that any substance which furnishes ${\text{H}}^{\text{+}}$ ions when added to ${\text{H}}_2\text{O}$ can be put into a class of acid. On the counterpart if any substance accepts ${\text{H}}^{\text{+}}$ ions when added to ${\text{H}}_2\text{O}$ , can be classified as base.

Conjugate acid- base pair contain 2 components, one that accept ${\text{H}}^{\text{+}}$ and other which donates shown as follows: $\text{HA}\left(aq\right)+{\text{H}}_2\text{O}\left(l\right)\to {\text{H}}_3{\text{O}}^{+}\left(aq\right)+{\text{A}}^{-}\left(aq\right)$

Where,

• $\text{HA}$ and ${\text{A}}^{-}$ is acid-conjugate base pair.
• ${\text{H}}_2\text{O}$ and ${\text{H}}_3{\text{O}}^{+}$ is base- conjugate pair.

Answer to Problem 17A

Relative strength of conjugate bases for given acids are as follows:

  ${\text{HClO}}_4<{\text{HNO}}_3<\text{HCN}<{\text{H}}_{\text{2}}\text{S}$

Explanation of Solution

Acids entirely dissociate into constituent ions in water so are called as strong acids. Strong acids have a weak conjugate base and weak acids have a strong conjugate base.

Order of relative strength of acidic nature in given acids is as follows:

  ${\text{HClO}}_4>{\text{HNO}}_3>\text{HCN}>{\text{H}}_{\text{2}}\text{S}$

Conclusion

Relative strength of conjugate bases for given acids are as follows:

  ${\text{HClO}}_4<{\text{HNO}}_3<\text{HCN}<{\text{H}}_{\text{2}}\text{S}$