Question

How will you arrange the following in ascending order of acid strength and oxidizing capacity\[?\]$HCl{O_4},\,HCl{O_3},\,HCl{O_2},\,HClO$.

Answer 1

Hint: Acid strength is the tendency of an acid to dissociate into a proton and an anion and the acidic strength increases with the increase in stability of the corresponding conjugate base of the acid. Oxidizing property of a compound depends on its ability to give oxygen and hence order of oxidizing power is inversely proportional to the acidic strength.

Complete step by step answer:
Acid strength is the tendency of an acid to dissociate into a proton and an anion and the acidic strength increases with the increase in stability of the corresponding conjugate base of the acid.
So at first we need to find the conjugate bases of the acids given in the question and then arrange them in ascending order of their stability in order to find the order of acidic strength.
The acids given in the question are $HCl{O_4},\,HCl{O_3},\,HCl{O_2},\,HClO$ and their corresponding conjugate bases are:
$HCl{O_4}\xrightarrow{{ - {H^ + }}}Cl{O_4}^ - $

Which has four resonating structures.
$HCl{O_3}\xrightarrow{{ - {H^ + }}}Cl{O_3}^ - $

Which has three resonating structures.
$HCl{O_2}\xrightarrow{{ - {H^ + }}}Cl{O_2}^ - $

Which has two resonating structures.
$HClO\xrightarrow{{ - {H^ + }}}Cl{O^ - }$

Which has no resonating structures.
Now, we know more the compound that has more number of resonating structures, that compound is stable.
Since $Cl{O_4}^ - ,\,Cl{O_3}^ - ,\,Cl{O_2}^ - ,\,Cl{O^ - }$ have $4,\,3,\,2,\,0$ resonating structures respectively. The stability order follows as: $Cl{O^ - } < Cl{O_2}^ - < Cl{O_3}^ - < Cl{O_4}^ - $.
Since acidic strength is directly proportional to the stability of the conjugate bases. Therefore the ascending order of the acidic strength follows the order:
$HClO < HCl{O_2} < HCl{O_3} < HCl{O_4}$.
Now, the oxidizing property of a compound depends on its ability to give oxygen and hence the order of oxidizing power is inversely proportional to the acidic strength.
Therefore the ascending order of oxidizing power or oxidizing capacity follows the order:
$HCl{O_4} < HCl{O_3} < HCl{O_2} < HClO$.

Note: You can also determine acidic strength of a compound as with increase in oxidation number of a particular halogen atom the acidic character of the corresponding oxoacid also increases. Also oxidizing property can be determined by the tendency of a compound to accept electrons and greater is the ability to accept electrons greater will be the oxidizing capacity.