Question

$C{l_2}{O_7}$ can be regarded as an anhydride of
A.Hypochlorous acid
B.Chlorous acid
C.Chloric acid
D.Perchloric acid

Answer 1

Anhydride is a chemical compound formed from another chemical compound by the removal of water from it. Here given anhydride is an acid anhydride formed by removal of water from an acid. To find acid, add water into the given anhydride.

Complete step by step answer:
-An anhydride is a chemical compound formed by another chemical compound by the removal of water from it. Here given anhydride is an acid anhydride formed by removal of water from an acid. Also, the oxidation of the state of the center atom remains the same as it is before removing water.
-To find the acid from which the anhydride $C{l_2}{O_7}$ is obtained, add water to it.
When we add water into it, it reacts with as the following reaction:
$C{l_2}{O_7} + {H_2}0 \to 2HCl{O_4}$
-We know that the name of $HCl{O_4}$ is perchloric acid.
-We can also solve using the oxidation state method. As the oxidation state of chlorine in $C{l_2}{O_7}$ is $+ 7$.
-And oxidation state of chlorine in all given acids is:
Hypochlorous acid $\left( {HClO} \right)$ is $+ 1$.
Chlorous acid $\left( {HCl{O_2}} \right)$ is $+ 3$.
Chloric acid $\left( {HCl{O_3}} \right)$ is $+ 5$.
Perchloric acid $\left( {HCl{O_4}} \right)$ is $+ 7$.
Then the oxidation state of chlorine is different in all given acids and only perchloric acid has the same oxidation number as given anhydride.
Then, $C{l_2}{O_7}$ is an anhydride of perchloric acid and the correct answer is option D.

Note:
Opposite of anhydride is hydride. Hydride of a compound is obtained by adding water into it. Then we can say that, $C{l_2}{O_7}$ is an anhydride of perchloric acid and perchloric acid is a hydride of $C{l_2}{O_7}$.