Copper(II) arsenate

Not to be confused with Copper arsenite.

Copper arsenate (Cu₃(AsO₄)₂·4H₂O, or Cu₅H₂(AsO₄)₄·2H₂O), also called copper orthoarsenate, tricopper arsenate, cupric arsenate, or tricopper orthoarsenate, is a blue or bluish-green powder insoluble in water and alcohol and soluble in aqueous ammonium and dilute acids.

Copper(II) arsenate

Names
IUPAC name Copper(II) arsenate
Other names Copper arsenate
Identifiers
CAS Number	7778-41-8 Y
3D model (JSmol)	Interactive image
ChemSpider	24279 Y
PubChem CID	26065
UNII	EV78GZO3YS Y
CompTox Dashboard (EPA)	DTXSID30894196
InChI InChI=1S/2AsH3O4.3Cu/c2*2-1(3,4)5;;;/h2*(H3,2,3,4,5);;;/q;;3*+2/p-6 Y Key: RKYSWCFUYJGIQA-UHFFFAOYSA-H Y InChI=1/2AsH3O4.3Cu/c2*2-1(3,4)5;;;/h2*(H3,2,3,4,5);;;/q;;3*+2/p-6 Key: RKYSWCFUYJGIQA-CYFPFDDLAM
SMILES [Cu+2].[Cu+2].[Cu+2].[O-][As]([O-])(=O)[O-].[O-][As]([O-])([O-])=O
Properties
Chemical formula	Cu3(AsO4)2
Molar mass	468.48 g/mol
Appearance	blue or bluish green powder
Density	5.2 g/cm3
Melting point	1,100 °C (2,010 °F; 1,370 K)
Solubility in water	insoluble
Solubility product (Ksp)	7.95×10−36[1]
Solubility	soluble in ammonia, dilute acids
Hazards
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 1 mg/m3 (as Cu)[2]
REL (Recommended)	TWA 1 mg/m3 (as Cu)[2]
IDLH (Immediate danger)	TWA 100 mg/m3 (as Cu)[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Uses

Copper arsenate is an insecticide used in agriculture. It is also used as a herbicide, fungicide, and a rodenticide. It is also used as a poison in slug baits.

Copper arsenate can also be a misnomer for copper arsenite, especially when meant as a pigment.

Natural occurrences

Anhydrous copper arsenate, Cu₃(AsO₄)₂, is found in nature as the mineral lammerite.^[3] Copper arsenate tetrahydrate, Cu₃(AsO₄)₂·4H₂O, occurs naturally as the mineral rollandite.^[4]

Related compounds

Copper arsenate hydroxide or basic copper arsenate (Cu(OH)AsO₄) is a basic variant with CAS number 16102-92-4.^[5] It is found naturally as the mineral olivenite. It is used as an insecticide, fungicide, and miticide. Its use is banned in Thailand since 2001.^[6]

See also

• Calcium arsenate
• Chromated copper arsenate
• Lead arsenate
• Paris Green (copper acetoarsenite)
• Scheele's Green (copper arsenite)