Question

What happens when (only give chemical reaction):
(i) ${Cl}_2$ gas is passed over dry slacked lime?
(ii) Potash alum is heated at red hot temperature?

Answer 1

(i) ${Cl}_2$ gas is passed over dry slacked lime, bleaching powder is obtained.
$Ca(OH{)}_2+C{l}_2\to CaOC{l}_2+H_{2}O$
(ii) Potash alum is heated at red hot temperature:
On heating, potash alum loses its water of crystallization. On rapidly heating to high temperature, the alum swells up and a porous mass called burnt alum is left behind.