Mercury(II) chloride

Mercury(II) chloride is an inorganic compound, HgCl₂, composed of mercury in the +2 oxidation state and chloride. It is highly toxic and dissolves in water.

Mercury–chlorine bond: A chemical bond between mercury and chlorine atoms or ions. The compound’s bonding helps explain its molecular structure and reactivity.
Calomel: The mineral form of mercury(I) chloride, Hg₂Cl₂, historically used in medicine and electrochemistry. Calomel is a less soluble mercury chloride once confused with other mercuric salts.
Alchemical mercury: Mercury as understood and used in alchemical traditions. Early preparation and naming of corrosive sublimate grew from alchemical work with mercury.
Globally Harmonized System of Classification and Labelling of Chemicals: An international framework for classifying chemical hazards and communicating them through labels and safety data sheets. Its hazard categories communicate the acute and chronic dangers of mercury(II) chloride.
Sublimation: The direct transition of a solid into a gas without passing through a liquid phase. Solid mercury(II) chloride can vaporize by sublimation, creating an inhalation hazard.
Mayer's reagent: A potassium tetraiodomercurate(II) solution used to detect alkaloids by forming precipitates. Mercury(II) chloride is used to prepare this classical alkaloid test reagent.
Corrosive sublimate: The historical name for mercury(II) chloride, associated with its preparation by sublimation. This name records a characteristic preparation method and its caustic reputation.
Chemical safety: Practices and systems that prevent harm from chemical substances and processes. Handling the compound requires controls against ingestion, skin contact, and inhalation.
Hydrolysis: A chemical reaction in which a substance is cleaved by reaction with water. Water can alter mercury(II) chloride’s speciation, especially as acidity changes.
Preservative: A substance added to materials to inhibit deterioration or microbial growth. The compound was once used as an antiseptic and preservative before its hazards curtailed use.

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