Question

The aqueous solution of \[N{H_4}N{O_3}\] ​ is acidic. This is due to the hydrolysis of
(A) Anion
(B) Cation
(C) Both anion and cation
(D) None of the above

Answer 1

Hint: To solve this, you need to know about the process of salt hydrolysis and its types. A salt is a type of compound that is formed when a Neutralisation reaction occurs between an acid and a base. This happens via the formation of cation and anion in the aqueous solution during ionization.

Complete step by step answer:
Salt Hydrolysis is a process in which a Salt Reacts with water to give back its respective acid and base. Basically, it’s the reverse of the neutralization reaction.
$BA\, + {H_2}O \Leftrightarrow HA + BOH$
Based on the type of Hydrolysis salts are divided into three types:
Acidic Salts
Basic Salts
Neutral Salts
Neutral Salts: These Salt are formed as a result of the neutralization reaction between a strong acid and a strong base. The pH of these salts is $7$. They don’t hydrolyze but get hydrated.
Example: $HCl\, + \,NaOH \to NaCl\, + {H_2}O$
Acidic Salt: These Salt are formed as a result of the neutralization reaction between a strong acid and a weak base. The pH of these salts is less than $7$. Example: \[N{H_4}N{O_3}\]. In the case of \[N{H_4}N{O_3}\] the ammonium ion is the conjugate acid of the base ammonia (\[N{H_3}\]) and the Nitrate ion is the conjugate base of Nitric acid. Since $HN{O_3}$v is a strong acid, its ${K_a}$ is immeasurably large and \[{K_b} \approx 0\] So, Nitrate ions will not undergo hydrolysis. Hence ($NH_4^ + $) is capable of reacting with water by donating a proton by acting as an acid. Hence ($NH_4^ + $) cations and inert anions ($NO_3^ - $) will result in an acidic solution.
Hence, The salt hydrolysis will be cationic.
Therefore, Option (B) is correct.

Note:
In case of acid is stronger than the base, the solution will be acidic and if the base is stronger than the acid, the solution will be alkaline. The salt of Weak acids undergoes anionic hydrolysis and that of the weak base undergoes cationic hydrolysis.