Kalomell

Kalomell, also known as mercury(I) chloride or mercurous chloride, is a chemical compound with the formula Hg₂Cl₂. It is a white, crystalline solid that is practically insoluble in water and alcohol. Historically, it was widely used as a medicinal purgative and diuretic, though its use has largely been discontinued due to its toxicity.

The compound is formed by the reaction of mercury with chlorine. It exists as discrete Hg₂²⁺ diatomic ions, each consisting of two mercury atoms bonded together, and chloride anions. This dimeric mercury(I) ion is characteristic of mercury(I) compounds. Kalomell can be prepared by the precipitation reaction between a soluble mercury(I) salt and a soluble chloride salt. For example, mixing a solution of mercury(I) nitrate with sodium chloride yields a precipitate of kalomell.

In industrial applications, kalomell has been used as a catalyst in certain organic reactions. It was also historically employed in the production of other mercury compounds. However, due to mercury's environmental and health concerns, its applications have significantly diminished. The toxicity of kalomell stems from its slow dissociation in the body, releasing mercury ions. Symptoms of mercury poisoning can include neurological damage, kidney problems, and gastrointestinal distress. Consequently, modern medicine and industry have largely replaced it with safer alternatives.