Question

$C{{l}_{2}}{{O}_{7}}$ is the anhydride of:
(a)- $HOCl$
(b)- $HCl{{O}_{2}}$
(c)- $HCl{{O}_{3}}$
(d)- $HCl{{O}_{4}}$

Answer 1

Hint: There are two forms of compound i.e., hydrated form and anhydride form. The hydrated form contains water molecules and when these water molecules are evaporated then the compound is called anhydride. Dichlorine heptoxide is the anhydrous form of perchloric acid.

Complete step by step answer:
-There are two forms of compound i.e., hydrated form and anhydride form. The hydrated form contains water molecules and when these water molecules are evaporated then the compound is called anhydride.
-$C{{l}_{2}}{{O}_{7}}$ is known as Dichlorine heptoxide and it is a chemical compound of group chlorine oxide.
-We can prepare the Dichlorine heptoxide by using a dehydrating agent on the perchloric acid, the reaction is given below:
$2HCl{{O}_{4}}+{{P}_{4}}{{O}_{10}}\to C{{l}_{2}}{{O}_{7}}+{{H}_{2}}{{P}_{4}}{{O}_{11}}$
-So we can see that perchloric acid is dehydrated or the water molecules are evaporated to form Dichlorine heptoxide, hence we can say that perchloric acid is the hydrated form of $C{{l}_{2}}{{O}_{7}}$ or $C{{l}_{2}}{{O}_{7}}$ is the anhydrous form of perchloric acid.
-Now the $C{{l}_{2}}{{O}_{7}}$ is distilled from the mixture, and on hydrolyses, it gives back perchloric acid.
-$C{{l}_{2}}{{O}_{7}}$ is a strong oxidizing agent and even it is explosive so it must be handled with care even a small mechanical shock or flame can cause the explosion. The oxidation of chlorine in $C{{l}_{2}}{{O}_{7}}$is +7 and it easily decomposes to form chlorine gas and oxygen gas, the reaction is given below:
$2C{{l}_{2}}{{O}_{7}}\to 2C{{l}_{2}}+7{{O}_{2}}$

Therefore, the correct answer is an option (d)- $HCl{{O}_{4}}$.

Note: $C{{l}_{2}}{{O}_{7}}$ does not get attacked with sulfur, phosphorus, or paper or when it is cold. In solution, both perchloric acid and dichlorine heptoxide are in equilibrium.