Question

Which is an example of autoprotolysis?
A. $ {{H}_{2}}O+{{H}_{2}}O\rightleftharpoons {{H}_{3}}{{O}^{+}}+O{{H}^{-}} $
B. $ N{{H}_{3}}+N{{H}_{3}}\rightleftharpoons NH_{4}^{+}+NH_{2}^{-} $
C. $ {{H}_{2}}S{{O}_{4}}+{{H}_{2}}S{{O}_{4}}\rightleftharpoons {{H}_{3}}SO_{4}^{+}+HSO_{4}^{-} $
D. All of the above

Answer 1

Hint: A chemical reaction in which transfer of a proton takes place from one molecule to another molecule in a solution is known as protolysis. When self-ionization of a molecule takes place during a chemical reaction i.e., transfer of a proton takes place from one molecule to another same molecule, then the process is termed as auto-protolysis.

Complete answer:
Auto-protolysis is a process in which a molecule donates its electron to its identical molecule. Some of the examples of auto-protolysis reaction are as follows:
Auto-protolysis in water:
When the self-ionization of water molecules takes place, a proton from one water molecule shifts to the other molecule of water due to which hydronium ions and hydroxide ions are formed. The reaction is as follows:
 $ {{H}_{2}}O+{{H}_{2}}O\rightleftharpoons {{H}_{3}}{{O}^{+}}+O{{H}^{-}} $
The auto-protolysis of water indicates the amphoteric nature of water i.e., in a chemical reaction, it can act like an acid as well as a base.
Auto-protolysis in ammonia:
Although self-ionization in ammonia is much weaker than water, as it is a better proton acceptor than water, the process of self-ionization is enhanced in liquid ammonia. When the self-ionization of ammonia takes place, then ammonium ions and amide ions are formed. The reaction is as follows:
 $ N{{H}_{3}}+N{{H}_{3}}\rightleftharpoons NH_{4}^{+}+NH_{2}^{-} $
Auto-protolysis in sulphuric acid:
Anhydrous sulphuric acid is amphoteric in nature i.e., it has a tendency to accept as well as donate protons in a chemical reaction. Hence it can show self-ionization reaction as follows:
 $ {{H}_{2}}S{{O}_{4}}+{{H}_{2}}S{{O}_{4}}\rightleftharpoons {{H}_{3}}SO_{4}^{+}+HSO_{4}^{-} $
As all the reactions given are the examples of the auto-protolysis process.
Thus, option (D) i.e., all of these are the correct answers.

Note:
It is important to note that, anhydrous here refers to a compound which does not contain any water molecule. Many chemical reactions hinder due to the presence of water molecules, therefore anhydrous compounds are widely used as water free reagents in many chemical reactions.