Question

Consider three generic acids: HX, HY, and HZ Rank these acids according to strength. Strongest acid HZ HY HX

Answer 1

Concepts and reason

The concept used to solve this problem is the strength of an acid.

It is the degree of dissociation of an acid that determines its strength. An acid which completely dissociates to give high concentration of ${{\rm{H}}^ + }$ ions is a strong acid, whereas an acid which partially dissociates and hence gives a low concentration of ${{\rm{H}}^ + }$ ions is a weak acid.

Fundamentals

A Bronsted acid is a substance having the capacity of donating a proton and a Bronsted base is a substance having the capacity of accepting a proton $\left( {{{\rm{H}}^{\rm{ + }}}\,{\rm{ion}}} \right)$ . So, a Bronsted acid is a proton donor and a Bronsted base is a proton accepter.

Consider the following graphic of ${\rm{HX}}$ .

${\rm{HX}}$ completely dissociates and hence it is a strong acid.

Consider the following graphic of ${\rm{HY}}$ .

${\rm{HY}}$ partially dissociates to give ${{\rm{H}}^ + }$ and ${{\rm{Y}}^ - }$ ions. Hence, it is a medium strength acid. It is a weaker acid than ${\rm{HX}}$ .

Consider the following graphic of ${\rm{HZ}}$ .

${\rm{HZ}}$ dissociates to a very small extent to give ${{\rm{H}}^ + }$ and ${{\rm{Z}}^ - }$ ions. Hence, it is a weak acid.

Ans:

The acids ranked according to their strength are: