Cadmium hydroxide

Cadmium hydroxide
IUPAC name

Cadmium(II) hydroxide
Identifiers
CAS number 21041-95-2 Y
PubChem 10313210
ChemSpider 8488675 Y
Jmol-3D images Image 1
Properties
Molecular formula Cd(OH)2
Molar mass 146.43 g/mol
Appearance white crystals
Density 4.79 g/cm3
Melting point

130 °C
Boiling point

300 °C (decomp)
Solubility in water 0.026 g/100 mL
Solubility soluble in dilute acids
Structure
Crystal structure hexagonal
Related compounds
Other anions Cadmium chloride,
Cadmium iodide
Other cations Zinc hydroxide,
Calcium hydroxide,
Magnesium hydroxide
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Cadmium hydroxide is an inorganic compound with the formula Cd(OH)2. It is a white crystalline ionic compound that is a key component of NiCd batteries.[1]

Preparation and reactions

Cadmium hydroxide is produced by treating cadmium nitrate with sodium hydroxide:

Cd(NO3)2 + 2 NaOH → Cd(OH)2 + 2 NaNO3

Attempted preparation from other cadmium salts is more complicated.[1] Cadmium hydroxide is more basic than zinc hydroxide. It forms the anionic complex Cd(OH)42- when treated with concentrated caustic soda solution. It forms complexes with cyanide, thiocyanate and ammonium ions when added to the solutions of these ions. Cadmium hydroxide loses water on heating, producing cadmium oxide. Decomposition commences at 130 °C and is complete at 300 °C. Reactions with mineral acids (HX) produce the corresponding cadmium salts (CdX2). With hydrochloric acid, sulfuric acid and nitric acid, the products are cadmium chloride, cadmium sulfate and cadmium nitrate, respectively.

Uses

It is generated in storage battery anodes, in nickel-cadmium and silver-cadmium storage batteries in its discharge:

Ni(OH)2 + Cd → Cd(OH)2 + Ni

The hydroxide is used in place of cadmium oxide for variety of operations.

References

  1. ^ a b Karl-Heinz Schulte-Schrepping, Magnus Piscator "Cadmium and Cadmium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2007 Wiley-VCH, Weinheim. doi:10.1002/14356007.a04_499.