Question

Is nitric acid the strongest acid and acetic acid the weakest?

Answer 1

Hint: According to Lewis theory acid are chemical substances which can accept a pair of electrons whereas according to Bronsted- Lowry theory acid is a chemical substance which can donate protons. Strong acids can completely ionize in dilute aqueous solution to release hydronium ion whereas; weak acids cannot completely ionize in dilute aqueous solution to release hydronium ion and a cation.

Complete answer:
Nitric acid with chemical formula $ HN{O_3} $ is one of the strongest acids and a highly corrosive mineral acid which turns blue litmus into red. Whereas, it gets completely dissociated into its ions when dissolved in water thereby releasing $ {H^ + } $ ion and nitrate ion. Moreover, the pH of nitric acid is 3. Thus, nitric acid satisfies all the parameters of a strong acid. So, nitric acid can be considered as one of the strongest acids.
Acetic acid with chemical formula $ C{H_3}COOH $ is one of the weakest acids as it does not completely dissociate into $ {H^ + } $ and $ C{H_3}CO{O^ - } $ ion, in dilute aqueous solution. The $ p{K_a} $ value of acetic acid is 4.76, moreover greater than the $ p{K_a} $ value of an acid, weaker is the acid. Thus, acetic acid is one of the weakest acids.

Note:
The $ p{K_a} $ value is inversely proportional to the ka value i.e. greater is the $ p{K_a} $ value lower is the $ {K_a} $ value and weaker is the acid similarly lower is the $ p{K_a} $ value, greater is the $ {K_a} $ value and stronger is the acid. Where, $ {K_a} $ is the acid dissociation constant and $ p{K_a} $ is the negative log of acid dissociation constant.