Chapter 16.1, Problem 2RQ

Interpretation Introduction

Interpretation: To identify the correct conjugate acid-base pair.

Concept introduction: Whenever an acid donates a proton, it changes into a base, and whenever a base accepts a proton, an acid is formed. Conjugate acid-base pair can be defined as an acid and a base which differ only by the absence or presence of a proton.

Answer to Problem 2RQ

a, e, and f represents correct conjugate acid-base pair.

Explanation of Solution

Reason for correct option:

(a)

  

Here, ${\text{OH}}^{-}$ abstracts proton from ${\text{HSO}}_{\text{4}}^{-}$ and hence ${\text{OH}}^{-}$ acts as base and ${\text{HSO}}_{\text{4}}^{-}$ acts as an acid.

(e)

  

Here, ${\text{OH}}^{-}$ abstracts proton from $\text{HCl}$ and hence ${\text{OH}}^{-}$ acts as base and $\text{HCl}$ acts as an acid.

(f)

  

Here, ${\text{OH}}^{-}$ abstracts proton from ${\text{H}}_2\text{O}$ and hence ${\text{OH}}^{-}$ acts as base and ${\text{H}}_2\text{O}$ acts as an acid.

Conclusion

Reason for incorrect options:

b)

  

Here, ${\text{OH}}^{-}$ abstracts proton from $\text{HBr}$ and hence ${\text{OH}}^{-}$ acts as base and $\text{HBr}$ acts as an acid.

  

Here, ${\text{OH}}^{-}$ abstracts roton from $\text{HBrO}$ and hence ${\text{OH}}^{-}$ acts as base and $\text{HBrO}$ acts as an acid.

c)

  

  ${\text{OH}}^{-}$ abstract proton from ${\text{H}}_2{\text{PO}}_4^{-}$ and hence ${\text{OH}}^{-}$ acts as base and ${\text{H}}_2{\text{PO}}_4^{-}$ acts as an acid.

  

Here, ${\text{OH}}^{-}$ abstracts proton from ${\text{HPO}}_4^{2-}$ and hence ${\text{OH}}^{-}$ acts as base and ${\text{HPO}}_4^{2-}$ acts as an acid.

d)

  

Here, ${\text{OH}}^{-}$ abstracts proton from ${\text{HNO}}_3$ and hence ${\text{OH}}^{-}$ acts as base and ${\text{HNO}}_3$ acts as an acid.

  

Here, ${\text{OH}}^{-}$ abstracts proton from ${\text{HNO}}_2$ and hence ${\text{OH}}^{-}$ acts as base and ${\text{HNO}}_2$ acts as an acid.