Question

What species are characteristics of acid and bases in the following solvents.
A.Liquid ammonia, anhydrous acetic acid
B.Anhydrous nitric acid
C.Anhydrous perchloric acid
D.Anhydrous sulphuric acid
E.Dinitrogen tetroxide

Answer 1

The solvent system for an acid base combines the concept of Arrhenius for acids and bases to the Bronsted lowry concept of acid-bases. It states that any molecule or substance which increases the concentration of solvent cations will be considered as an acid whereas the substance which increases the concentration of solvent anions will be termed as a base.

Complete answer:
The solvent system is based on the concept of autoionization of the solvents and it defines the acids and bases in terms of concentration of cations and anions present in the solution.
For the given solvents, the autoionization reactions takes place as follows:
(a) liquid ammonia, anhydrous acetic acid:
Liquid ammonia on autoionization gives ammonium ion i.e., $NH_4^ +$ which is considered as acidic species and amide ion i.e., $NH_2^ -$ which is considered as basic species. The autoionization reaction of ammonia takes place as follows:
$2N{H_3} \rightleftharpoons NH_4^ + + NH_2^ -$
Anhydrous acetic acid on autoionization gives $C{H_3}COOH_2^ +$ which is considered as acidic species and acetate ion i.e., $C{H_3}CO{O^ - }$ which is considered as basic species. The autoionization reaction of acetic acid takes place as follows:
$2C{H_3}COOH \rightleftharpoons C{H_3}CO{O^ - } + C{H_3}COOH_2^ +$
(b) Anhydrous nitric acid:
Anhydrous nitric acid on autoionization gives ${H_2}NO_3^ +$ which is considered as acidic species and nitrate ion i.e., $NO_3^ -$ which is considered as basic species. The autoionization reaction of nitric acid takes place as follows:
$2HN{O_3} \rightleftharpoons NO_3^ - + {H_2}NO_3^ +$
(b) Anhydrous perchloric acid:
Anhydrous perchloric acid on autoionization gives ${H_2}ClO_4^ +$ which is considered as acidic species and perchlorate ion i.e., $ClO_4^ -$ which is considered as basic species. The autoionization reaction of perchloric acid takes place as follows:
$2HCl{O_4} \rightleftharpoons {H_2}ClO_4^ + + ClO_4^ -$
(b) Anhydrous sulphuric acid:
Anhydrous sulphuric acid on autoionization gives ${H_3}SO_4^ +$ which is considered as acidic species and hydrogen sulphate i.e., $HSO_4^ -$ which is considered as basic species. The autoionization reaction of sulphuric acid takes place as follows:
$2{H_2}S{O_4} \rightleftharpoons {H_3}SO_4^ + + HSO_4^ -$
(b) Dinitrogen tetroxide:
Dinitrogen tetroxide on autoionization gives nitronium ion i.e., $NO_2^ +$ which is considered as acidic species and nitrite ion i.e., $NO_2^ -$ which is considered as basic species. The autoionization reaction of dinitrogen tetroxide takes place as follows:
${N_2}{O_4} \rightleftharpoons NO_2^ + + NO_2^ -$

Note:
It is important to note that the term anhydrous used with acids indicates that the acids are present in their pure state i.e., it does not contain any water molecule as a constituent. These compounds are known as anhydrates and have a tendency to absorb water from air. Moreover, no release of the water molecule is observed on heating anhydrates.