Question

The correct order of acidic strength is:-
A. \[{\text{ }}HClO{\text{ }} < {\text{ }}HCl{O_2}{\text{ }} < {\text{ }}HCl{O_3}{\text{ }} < {\text{ }}HCl{O_4}\]
B. \[{\text{ }}HCl{O_4}{\text{ }} < {\text{ }}HClO{\text{ }} < {\text{ }}HCl{O_2}{\text{ }} < {\text{ }}HCl{O_3}\]
C. \[HCl{O_2}{\text{ }} < {\text{ }}HCl{O_3}{\text{ }} < {\text{ }}HCl{O_4}{\text{ }} < {\text{ }}HClO\]
D. \[{\text{ }}HCl{O_4}{\text{ }} < {\text{ }}HCl{O_3}{\text{ }} < {\text{ }}HCl{O_2}{\text{ }} < {\text{ }}HClO\]

Answer 1

Hint: In this question, we need to arrange the given compounds according to their acidic strength. The acidic character of the resulting oxoacid increases with the rise in the single halogen atom's oxidation number.

Complete step by step solution:
According to the Lowry-Bronsted concept, a strong acid has a weak conjugate base, and a weak acid has a strong conjugate base. Now, let us consider the stabilities of the conjugate bases:
\[ClO < Cl{O_2} < Cl{O_3} < Cl{O_4}\] formed from these acids \[HClO,{\text{ }}HCl{O_2},{\text{ }}HCl{O_3},HCl{O_4}\] respectively.
These anions are stabilized to a greater extent; it has a lesser attraction for protons and will behave as a weaker base. Consequently, the corresponding acid will be most vital because the weak conjugate base has strong acid and the strong conjugate base has weak acid and vice versa.
Now the charge stabilization will be minimum in $ClO$. The charge stabilization increases in the order:
\[ClO < Cl{O_2} < Cl{O_3} < Cl{O_4}\]
This means that \[ClO\] will have minimum stability and will have a top attraction for H+. Thus, \[ClO\] will be the most robust base, and so its conjugate acid \[HClO\] will be the weakest. Similarly, in this series \[Cl{O_4}\] is the weakest base (maximum stabilized), and its conjugate acid \[HCl{O_4}\] is the most potent acid.
Hence, the acidic strength increases in the order:
\[{\text{ }}HClO{\text{ }} < {\text{ }}HCl{O_2}{\text{ }} < {\text{ }}HCl{O_3}{\text{ }} < {\text{ }}HCl{O_4}\]

Therefore the correct answer is option A.

Note:
Students should note that acidity is directly proportional to the number of oxygens in the given atom. While solving the questions students should know the correct order of stability of bases and acids. They usually get confused with the Lowry-Bronsted concept and make mistakes in determining the stability of Conjugate compounds.