Cadmium sulfate

Cadmium sulfate is the name of a series of related inorganic compounds with the formula CdSO₄·xH₂O. The most common form is the monohydrate CdSO₄·H₂O, but two other forms are known CdSO₄·8⁄3H₂O and the anhydrous salt (CdSO₄). All salts are colourless and highly soluble in water.

Cadmium sulfate

Cadmium sulfate
Names
IUPAC name Cadmium(II) sulfate
Other names Sulfuric acid, cadmium salt (1:1),
Identifiers
CAS Number	10124-36-4 Y 7790-84-3 (octahydrate) N 13477-21-9 (tetrahydrate) N
3D model (JSmol)	Interactive image
ChEBI	CHEBI:50292 Y CHEBI:86157 (octahydrate)
ChemSpider	23335 Y
ECHA InfoCard	100.030.288
EC Number	233-331-6
Gmelin Reference	8295
PubChem CID	24962 (anhydrous) 23618914 (tetrahydrate) 16211218 (octahydrate)
RTECS number	EV2700000
UNII	947UNF3Z6O Y
UN number	2570
CompTox Dashboard (EPA)	DTXSID1020229
InChI InChI=1S/Cd.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2 Y Key: QCUOBSQYDGUHHT-UHFFFAOYSA-L Y InChI=1/Cd.H2O4S/c;1-5(2,3)4/h;(H2,1,2,3,4)/q+2;/p-2 Key: QCUOBSQYDGUHHT-NUQVWONBAG
SMILES [Cd+2].[O-]S([O-])(=O)=O
Properties
Chemical formula	CdSO4 CdSO4·H2O (monohydrate) 3CdSO4·8H2O (octahydrate)
Molar mass	208.47 g/mol (anhydrous) 226.490 g/mol (monohydrate) 769.546 g/mol (octahydrate)
Appearance	White hygroscopic solid
Odor	odorless
Density	4.691 g/cm3 (anhydrous) 3.79 g/cm3 (monohydrate) 3.08 g/cm3 (octahydrate)[1]
Melting point	1,000 °C (1,830 °F; 1,270 K) (anhydrous) 105 °C (monohydrate) 40 °C (octahydrate)
Boiling point	(decomposes to basic sulfate and then oxide)
Solubility in water	anhydrous: 75 g/100 mL (0 °C) 76.4 g/100 mL (25 °C) 58.4 g/100 mL (99 °C) monohydrate: 76.7 g/100 mL (25 °C) octahydrate: very soluble
Solubility	slightly soluble in methanol, ethyl acetate insoluble in ethanol
Magnetic susceptibility (χ)	−59.2·10−6 cm3/mol
Refractive index (nD)	1.565
Structure
Crystal structure	orthorhombic (anhydrous) monoclinic (hepta & octahydrate)
Thermochemistry
Std molar entropy (S⦵298)	123 J·mol−1·K−1[2]
Std enthalpy of formation (ΔfH⦵298)	−935 kJ·mol−1[2]
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H330, H340, H350, H360, H372, H410
Precautionary statements	P201, P202, P260, P264, P270, P271, P273, P281, P284, P301+P310, P304+P340, P308+P313, P310, P314, P320, P321, P330, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)	3 1 0
Lethal dose or concentration (LD, LC):
LD50 (median dose)	280 mg/kg (oral, rat)
NIOSH (US health exposure limits):
PEL (Permissible)	[1910.1027] TWA 0.005 mg/m3 (as Cd)[3]
REL (Recommended)	Ca[3]
IDLH (Immediate danger)	Ca [9 mg/m3 (as Cd)][3]
Safety data sheet (SDS)
Related compounds
Other anions	Cadmium acetate, Cadmium chloride, Cadmium nitrate
Other cations	Zinc sulfate, Calcium sulfate, Magnesium sulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Structure, preparation, and occurrence

Portion of structure of CdSO4 illustrating the distorted tetrahedral geometry at Cd (dark blue spheres).^[4]

X-ray crystallography shows that CdSO₄·H₂O is a typical coordination polymer. Each Cd²⁺ center has octahedral coordination geometry, being surrounded by four oxygen centers provided by four sulfate ligands and two oxygen centers from the bridging water ligands.^[5]

Cadmium sulfate hydrate can be prepared by the reaction of cadmium metal or its oxide or hydroxide with dilute sulfuric acid:

CdO + H₂SO₄ → CdSO₄ + H₂O

Cd + H₂SO₄ → CdSO₄ + H₂

The anhydrous material can be prepared using sodium persulfate:^{[citation needed]}

Cd + Na₂S₂O₈ → CdSO₄ + Na₂SO₄

Cadmium sulfates occur as the following rare minerals drobecite (CdSO₄·4H₂O), voudourisite (monohydrate), and lazaridisite (the 8/3-hydrate).

Applications

Cadmium sulfate is used widely for the electroplating of cadmium in electronic circuits. It is also a precursor to cadmium-based pigment such as cadmium sulfide. It is also used for electrolyte in a Weston standard cell as well as a pigment in fluorescent screens.