Copper arsenate (Cu
3(AsO
4)
2·4H
2O, or Cu
5H
2(AsO
4)
4·2H
2O), 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
The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternar ...
and dilute acids. Its
CAS number
A CAS Registry Number (also referred to as CAS RN or informally CAS Number) is a unique identification number assigned by the Chemical Abstracts Service (CAS), US to every chemical substance described in the open scientific literature. It inclu ...
is or .
Uses
Copper arsenate is an
insecticide used in agriculture. It is also used as a
herbicide,
fungicide, and a
rodenticide
Rodenticides are chemicals made and sold for the purpose of killing rodents. While commonly referred to as "rat poison", rodenticides are also used to kill mice, squirrels, woodchucks, chipmunks, porcupines, nutria, beavers, and voles. Despite ...
. 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
A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic comp ...
.
Natural occurrences
Anhydrous copper arsenate, Cu
3(AsO
4)
2, is found in nature as the mineral lammerite. Copper arsenate tetrahydrate, Cu
3(AsO
4)
2·4H
2O, occurs naturally as the mineral rollandite.
Related compounds
Copper arsenate hydroxide or basic copper arsenate (Cu(OH)AsO
4) is a basic variant with CAS number . It is found naturally as the mineral
olivenite
Olivenite is a copper arsenate mineral, formula Cu2 As O4O H. It crystallizes in the monoclinic system (pseudo-orthorhombic), and is sometimes found in small brilliant crystals of simple prismatic habit terminated by domal faces. More commonly ...
. It is used as an insecticide, fungicide, and
miticide. Its use is banned in Thailand since 2001.
See also
*
Lead arsenate
Lead hydrogen arsenate, also called lead arsenate, acid lead arsenate or LA, chemical formula PbHAsO4, is an inorganic insecticide used primarily against the potato beetle.
Lead arsenate was the most extensively used arsenical insecticide.Peryea ...
*
Calcium arsenate
*
Paris Green (copper acetoarsenite)
*
Chromated copper arsenate Chromated copper arsenate (CCA) is a wood preservative containing compounds of chromium, copper, and arsenic, in various proportions. It is used to impregnate timber and other wood products, especially those intended for outdoor use, in order to pr ...
*
Scheele's Green (copper arsenite)
References
External links
National Pollutant Inventory - Copper and compounds fact sheet
{{Insecticides
Arsenates
Copper(II) compounds
Inorganic insecticides
Arsenical herbicides
Rodenticides
Fungicides