Chapter 18, Problem 18.87P

Interpretation Introduction

Interpretation:

Two factors for the difference in acid strength in Perchloric acid (${\text{HClO}}_{\text{4}}$), is the strongest of the halogen oxoacids, and hypoiodous acid ($\text{HIO}$), is the weakest has to explained.

Concept introduction:

Increasing acid strength:

Acids strength is mainly depending on the dissociation of ions, strong acids dissociates completely and weak acid dissociate slightly.

The hydrohalic acids are strong acids ($\text{HCl, HBr, and HI}$) other than ($\text{HF}$).

Oxoacids are strong acid when the number of oxygen excess than the ionizable proton by two or more oxygen atom for example, ${\text{HNO}}_{\text{3}}{\text{, H}}_{\text{2}}{\text{SO}}_{\text{4}}{\text{, and HClO}}_{\text{4}}$.

The hydrogen atom which is not bonded to halogen atom or oxygen atoms are weak acid for example ${\text{HCN, H}}_{\text{2}}\text{S}\text{.}$

The number of protons is equal to number oxygen in Oxoacids are weak acid for example ${\text{ HClO, HNO}}_{\text{2}}{\text{, and H}}_{\text{3}}{\text{PO}}_{\text{4}}$. In general, carboxylic acids are weak acid ($\text{RCOOH}$).

The acid strength is depending on the ${\text{K}}_{\text{a}}$ value, if the  ${\text{K}}_{\text{a}}$ value is larger the stronger the acid. 

Electronegativity:

It is the ability of atom to attract a lone pair of electrons towards itself in a substrate. Electronegativity property follows the trend that it increases across the periods and decreases down the column in the periodic table.