CdOH2

CdOH2, more commonly written as Cd(OH)2, is cadmium(II) hydroxide. It is an inorganic white solid that forms when cadmium salts are treated with bases. In water its solubility is very limited, and it tends to precipitate as a gelatinous material. Cd(OH)2 is often encountered as small, poorly crystalline particles rather than as a well-defined crystal.

Preparation and reactions: Cd(OH)2 can be prepared by neutralizing cadmium salts (such as CdSO4 or CdCl2) with a strong base, for example NaOH, to give Cd(OH)2(s). It readily reacts with acids to re-form Cd2+ ions. In strongly alkaline solutions, Cd(OH)2 can dissolve to give hydroxo complexes such as [Cd(OH)4]2-, reflecting a limited solubility equilibrium in basic media.

Structure and properties: Cadmium hydroxide adopts a brucite-like, layered structure with octahedrally coordinated Cd2+ centers linked by hydroxide ions. The material is thermally unstable with respect to dehydration; heating yields cadmium oxide, CdO, plus water. It is sensitive to oxidation and can convert to other cadmium-containing species under certain conditions.

Applications: Cd(OH)2 serves as a convenient precursor to cadmium oxide and various cadmium salts used in pigments, electronics, and electrochemical applications. In nickel–cadmium batteries, the negative electrode operates through cadmium-based reactions that involve the formation of Cd(OH)2 during discharge.

Safety: Cadmium compounds are highly toxic and carcinogenic. Exposure through inhalation, ingestion, or skin contact should be minimized, and proper containment and disposal procedures should be followed in accordance with regulatory guidance.