Question

Indicate the types of chemical reactions represented by the following equation:
$2\mathrm{HOCl}\left(\mathrm{aq}\right)\stackrel{\mathrm{light}}{\to }2\mathrm{HCl}\left(\mathrm{aq}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$

Answer 1

1. Type of reaction

• Combination reaction: Reaction in which two or more reactants combine to form a single product. $\mathrm{A}+\mathrm{B}\to \mathrm{C}$
• Decomposition reaction: Reaction in which reactant is broken down into two or more products in the presence of heat, light or electricity. $\mathrm{A}\to \mathrm{B}+\mathrm{C}$
• Displacement reaction: Reaction in which one of the higher reactive element displaces a less reactive element from its solution. $\mathrm{A}+\mathrm{BC}\to \mathrm{AC}+\mathrm{B}$
• ( Here A is more reactive than B)
• Double displacement reaction: Reaction in which ions of both the reactants interchange their place and form new compounds. $\mathrm{AB}+\mathrm{CD}\to \mathrm{AD}+\mathrm{CB}$

2. Reaction

$2\mathrm{HOCl}\left(\mathrm{aq}\right)\stackrel{\mathrm{light}}{\to }2\mathrm{HCl}\left(\mathrm{aq}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$

Hypochlorous acid Hydrochloric acid Oxygen

• Here in the presence of light hypochlorous acid dissociate into hydrochloric acid and oxygen.
• Since one reactant is breaking down into two products so it is a decomposition reaction.
• Also, we can say it is endothermic in nature because light energy is absorbed to break down hypochlorous acid.
• Since in presence of light decomposition is taking place we call this as photochemical decomposition reaction.