Question

What happens when chlorine is passed over slaked lime at $313\mathrm{K}$ and write chemical equation of the reaction involved and state two uses of the product obtained.

Answer 1

Slaked lime:

• Slaked lime, or calcium hydroxide $\left(\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\right)$, is an inorganic substance.
• When calcium oxide $\left(\mathrm{CaO}\right)$ is combined with water $\left({\mathrm{H}}_2\mathrm{O}\right)$, it produces a colourless crystal of slaked lime.

Reaction of chlorine with slaked lime:

• When chlorine $\left({\mathrm{Cl}}_2\right)$ is passed over slaked lime at $313\mathrm{K}$, it absorbs quickly, yielding bleaching powder.
• The reaction is as follows:

$\underset{\left(\mathrm{Chlorine}\right)}{{\mathrm{Cl}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Slaked}\mathrm{lime}}{\mathrm{Ca}{\left(\mathrm{OH}\right)}_2\left(\mathrm{s}\right)}\to \underset{\left(\mathrm{Bleaching}\mathrm{powder}\right)}{{\mathrm{CaOCl}}_2\left(\mathrm{s}\right)}+\underset{\left(\mathrm{Water}\right)}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

• The reaction of chlorine with dry slaked lime produces bleaching powder, which is calcium oxychloride.

Uses of bleaching powder:

• It is used in the paper and textile industries as a bleaching agent.
• It's a disinfectant that's used to make drinkable water by disinfecting water.