Question

Slaked lime reacts with chlorine to give:
A) ${\rm{CaC}}{{\rm{l}}_2}$
B) ${\rm{CaO}}$
C) ${\rm{Ca}}{\left( {{\rm{OCl}}} \right)_2}$
D) ${\rm{CaC}}{{\rm{O}}_3}$

Answer 1

Slaked lime is calcium hydroxide. It is basic in nature and reacts with chlorine to give bleaching powder.

Complete step by step answer:
Calcium hydroxide is also known as slaked lime.
Chlorine reacts with dry slaked lime to give a mixture of calcium chloride and calcium hypochlorite.

{\rm{ Ca}}{\left( {{\rm{OH}}} \right)_2} + {\rm{ C}}{{\rm{l}}_2} \to {\rm{Ca}}{\left( {{\rm{OCl}}} \right)_2} + {\rm{ }}{{\rm{H}}_{\rm{2}}}{\rm{O}} \\\ {\rm{2 Ca}}{\left( {{\rm{OH}}} \right)_2} + 2{\rm{ C}}{{\rm{l}}_2} \to {\rm{Ca}}{\left( {{\rm{OCl}}} \right)_2} + {\rm{CaC}}{{\rm{l}}_2} + {\rm{2 }}{{\rm{H}}_{\rm{2}}}{\rm{O}} \\\ \end{array}$$ Bleaching powder is $${\rm{Ca}}{\left( {{\rm{OCl}}} \right)_2}$$ Thus, during the reaction of chlorine gas with dry slaked lime, bleaching powder is obtained. If the slaked lime is not dry, then chlorine reacts with water to form hydrochloric acid and hypochlorus acid. $$\begin{array}{l} {\rm{ C}}{{\rm{l}}_2} + {{\rm{H}}_{\rm{2}}}{\rm{O}} \to {\rm{HCl}} + {\rm{HOCl}} \\\ {\rm{ HOCl }} \to {\rm{ HCl + }}\left[ {\rm{O}} \right] \\\ \end{array}$$ The nascent oxygen released during the process gives oxidising and bleaching properties to chlorine. **Thus Option A and C are correct** **Note:** Write correct formula for slaked lime. Calcium oxide is quick lime, calcium hydroxide is slaked lime whereas calcium carbonate is limestone.