Question

\[{\rm{CaOC}}{{\rm{l}}_{\rm{2}}}{\rm{ + }}{{\rm{H}}_{\rm{2}}}{\rm{O + C}}{{\rm{O}}_{\rm{2}}}{\rm{ }} \to {\rm{ CaC}}{{\rm{O}}_3}{\rm{ + CaC}}{{\rm{l}}_2}{\rm{ + HOCl }}\] This reaction is simply:
A ) oxidation
B ) reduction
C ) redox
D ) hydrolysis in presence of \[{\rm{C}}{{\rm{O}}_{\rm{2}}}\]

Answer 1

Hint: In presence of water and carbon dioxide, calcium hypochlorite forms calcium carbonate, calcium chloride and hypochlorous acid. Write the oxidation number of each element in the reactants and in the product. Check if there is a change in the oxidation number of any element during the reaction.

Complete step by step answer:
Write the given reaction:

\[{\rm{CaOC}}{{\rm{l}}_{\rm{2}}}{\rm{ + }}{{\rm{H}}_{\rm{2}}}{\rm{O + C}}{{\rm{O}}_{\rm{2}}}{\rm{ }} \to {\rm{ CaC}}{{\rm{O}}_3}{\rm{ + CaC}}{{\rm{l}}_2}{\rm{ + HOCl }}\]

This is an unbalanced reaction that needs to be balanced.
There are two calcium atoms on the product side whereas only one calcium atom is present on the reactant side. To balance calcium atoms, add coefficient two to \[{\rm{CaOC}}{{\rm{l}}_{\rm{2}}}\] on the reactant side.

\[{\rm{2 CaOC}}{{\rm{l}}_{\rm{2}}}{\rm{ + }}{{\rm{H}}_{\rm{2}}}{\rm{O + C}}{{\rm{O}}_{\rm{2}}}{\rm{ }} \to {\rm{ CaC}}{{\rm{O}}_3}{\rm{ + CaC}}{{\rm{l}}_2}{\rm{ + HOCl }}\]

There are four chlorine atoms on the reactant side. But there are only three chlorine atoms on the product side. To balance chlorine atoms, add coefficient two to \[{\rm{HOCl }}\] on the product side.

\[{\rm{2 CaOC}}{{\rm{l}}_{\rm{2}}}{\rm{ + }}{{\rm{H}}_{\rm{2}}}{\rm{O + C}}{{\rm{O}}_{\rm{2}}}{\rm{ }} \to {\rm{ CaC}}{{\rm{O}}_3}{\rm{ + CaC}}{{\rm{l}}_2}{\rm{ + 2 HOCl }}\]

Hydrogen, oxygen and carbon atoms are already balanced. This is the balanced chemical equation.
This equation represents a hydrolysis reaction in presence of \[{\rm{C}}{{\rm{O}}_{\rm{2}}}\].

Hence, the option D ) is the correct option.

Additional Information: In the hydrolysis reaction, the proton from water combines with anion of salt, and hydroxide ion from water combines with cation of the salt. When the same hydrolysis is carried out in presence of carbon dioxide, the carbonate ion (obtained from carbonic acid formed by the action of water on carbon dioxide) combines with cation of salt. The protons from water combine with anions of salt.

${\rm{2 CaOC}}{{\rm{l}}_{\rm{2}}}{\rm{ + }}{{\rm{H}}_{\rm{2}}}{\rm{O + C}}{{\rm{O}}_{\rm{2}}}{\rm{ }} \to {\rm{ CaC}}{{\rm{O}}_3}{\rm{ + CaC}}{{\rm{l}}_2}{\rm{ + 2 HOCl }}$

No change in the oxidation number of elements in the reactants and products. Hence, it is not a redox reaction. Hence, options A ) B ) C ) are incorrect options.

Note: In a redox reaction, both oxidation and reduction takes place simultaneously. Only oxidation, or only reduction is not possible. In \[{\rm{CaOC}}{{\rm{l}}_{\rm{2}}}\] molecule, one chlorine atom has oxidation number of +1 and other chlorine atom has oxidation number of -1.