Question

Slaked lime reacts with chlorine to give:
(A) baking soda
(B) washing soda
(C) bleaching powder
(D) cement

Answer 1

Hint: Slaked lime is basically the calcium hydroxide. The reaction of chlorine with dry slaked lime gives a mixture of calcium chloride and calcium hypochlorite.

Complete answer:
Let us a quick look towards the reaction of slaked lime with chlorine;
Slaked lime i.e. calcium hydroxide when reacts with dry slaked lime gives a mixture of two compounds as,
$2Ca{{\left( OH \right)}_{2}}+2C{{l}_{2}}\to Ca{{\left( OCl \right)}_{2}}+CaC{{l}_{2}}+2{{H}_{2}}O$
The resulting mixture of calcium chloride and calcium hypochlorite adds to give a specified product i.e. bleaching powder as;
$Ca{{\left( OCl \right)}_{2}}+CaC{{l}_{2}}\to C{{a}_{2}}{{\left( OCl \right)}_{2}}C{{l}_{2}}$
This will eventually result as bleaching powder i.e. $Ca\left( OCl \right)Cl$ .
Now, if the slaked lime is not dry then, chlorine reacts with water to give hydrochloric acid and hypochlorous acid as,
$\begin{align}
& C{{l}_{2}}+{{H}_{2}}O\to HCl+HOCl \\
& HOCl\to HCl+\left[ O \right] \\
\end{align}$
The nascent oxygen thus obtained during the process gives oxidising and bleaching properties to chlorine.
Thus, we can see that the reaction of slaked lime with chlorine gives bleaching powder.

Therefore, option (C) is correct.

Note: Do note that quick lime i.s. calcium oxide, slaked lime i.s. calcium hydroxide and limestone i.s. calcium carbonate is different. Bleaching powder is the mixture of calcium hypochlorite and calcium chloride.