Question

Which of the given dilute acids react with bleaching powder to release chlorine gas?

• A. Sulphuric acid
• B. Nitric acid
• C. Hydrochloric acid
• D. Acetic acid

Answer 1

Answer: (A), (C)

Hydrochloric acid

The chemical formula of bleaching powder is ${\mathrm{CaOCl}}_2$. When dilute sulphuric acid and dilute hydrochloric acid are added to it, it reacts completely with them to release chlorine gas as shown below:
${\mathrm{CaOCl}}_2\left(s\right)+H_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{CaSO}}_4\left(s\right)+{\mathrm{Cl}}_2\left(g\right)+H_{2}O\left(l\right){\mathrm{CaOCl}}_2\left(s\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{CaCl}}_2\left(s\right)+{\mathrm{Cl}}_2\left(g\right)+H_{2}O\left(l\right)$