Cadmium hydroxide

Cadmium hydroxide
Cadmium hydroxide structure
Cadmium hydroxide structure
Names
IUPAC name
Cadmium(II) hydroxide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.040.137 Edit this at Wikidata
UNII
  • InChI=1S/Cd.2H2O/h;2*1H2/q+2;;/p-2 checkY
    Key: PLLZRTNVEXYBNA-UHFFFAOYSA-L checkY
  • InChI=1/Cd.2H2O/h;2*1H2/q+2;;/p-2
    Key: PLLZRTNVEXYBNA-NUQVWONBAA
  • [Cd+2].[OH-].[OH-]
Properties
Cd(OH)2
Molar mass 146.43 g/mol
Appearance white crystals
Density 4.79 g/cm3
Melting point 130 °C (266 °F; 403 K)
Boiling point 300 °C (572 °F; 573 K) (decomposes)
0.026 g/100 mL
7.2×10−15
Solubility soluble in dilute acids
Acidity (pKa) 10
−41.0·10−6 cm3/mol
Structure
hexagonal
Thermochemistry
96 J·mol−1·K−1
−561 kJ·mol−1
Hazards
NIOSH (US health exposure limits):
PEL (Permissible)
 [1910.1027] TWA 0.005 mg/m3 (as Cd)
REL (Recommended)
 Ca
IDLH (Immediate danger)
 Ca [9 mg/m3 (as Cd)]
Related compounds
Other anions
 Cadmium chloride,
Cadmium iodide
Other cations
 Zinc hydroxide,
Calcium hydroxide,
Magnesium hydroxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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 nickel–cadmium battery.

Structure

Cadmium hydroxide adopts the same structure as Mg(OH)2, consisting of slabs of metal centers, each bonded by six hydroxide ligands. The Cd(OH)2 structure is a recurring motif in inorganic chemistry. For example it is adopted by vanadium ditelluride.

Preparation, and reactions

Cadmium hydroxide is produced by treating an aqueous solution containing Cd2+ (say cadmium nitrate) with sodium hydroxide:

Cd(NO3)2 + 2 NaOH → Cd(OH)2 + 2 NaNO3

Cd(OH)2 and cadmium oxide exhibit similar reactions. Cadmium hydroxide is more basic than zinc hydroxide. It forms the anionic complex [Cd(OH)4]2− when treated with concentrated base. It forms complexes with cyanide, thiocyanate, and ammonia.

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) gives 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:

2 NiO(OH) + 2 H2O + Cd → Cd(OH)2 + 2 Ni(OH)2

References

  1. ↑ John Rumble (June 18, 2018). CRC Handbook of Chemistry and Physics (99 ed.). CRC Press. pp. 5–188. ISBN 978-1138561632.
  2. ↑ Perrin, D. D., ed. (1982) [1969]. Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution. IUPAC Chemical Data (2nd ed.). Oxford: Pergamon (published 1984). Entry 22. ISBN 0-08-029214-3. LCCN 82-16524.
  3. 1 2 Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A21. ISBN 978-0-618-94690-7.
  4. 1 2 3 "#0087". NIOSH Pocket Guide to Chemical Hazards. National Institute for Occupational Safety and Health.
  5. 1 2 3 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.
  6. ↑ Hemmingsen, L.; Bauer, R.; Bjerrum, M. J.; Schwarz, K.; Blaha, P.; Andersen, P., "Structure, Chemical Bonding, and Nuclear Quadrupole Interactions of β-Cd(OH)2:  Experiment and First Principles Calculations", Inorganic Chemistry 1999, volume 38, 2860-2867. doi:10.1021/ic990018e
  7. ↑ Bronsema, K.D.; Bus, G.W.; Wiegers, G.A. (1984). "The Crystal Structure of Vanadium Ditelluride, V1+xTe2". Journal of Solid State Chemistry. 53 (3): 415–421. doi:10.1016/0022-4596(84)90120-8.
  8. 1 2 F. Wagenknecht; R. Juza (1963). "Cadmium hydroxide". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 2. NY, NY: Academic Press. p. 1096.