Preparation, properties and uses of (i) Calomel (ii) Corrosive Sublimate

Hg2Cl2 is known as calomel. It is prepared by heating HgCl2 and Hg in an iron vessel.

It can also be prepared by mixing mercury salt with chloride ions.


1) It is a white powder which is insoluble in water.

2) Hg2Cl2 on heating dissociates into HgCl2 and Hg.

action of calomel on heat


Corrosive sublimate

HgCl2 is a corrosive sublimate, which is prepared by passing chlorine over heated mercury or mercury chloride.

It can also be prepared by heating mercury sulphate with NaCl.

action of mercury sulphate with NaCl


1) It is a crystalline solid.

2) It is soluble in hot water, ethanol and ether.

3) HgCl2 reacts with KI and forms a colorless solution known as Nessler's reagent.

nessler s reaction

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