2434. Cobaltous Arsenate

Nomenclature

CAS number: 7785-24-2
C.I. 77350.
As2Co3O8; mol wt 454.64.
As 32.96%, Co 38.89%, O 28.15%.
Co3(AsO4)2.

Description and references

Octahydrate occurs in nature as erythrite or cobalt bloom. Prepn: Gmelins, Cobalt (8th ed.) 58, (part A), 305 (1932) and supplement, 752 (1961); Charles-Messance et al., Bull. Soc. Chim. Fr. 1962, 574. See Colour Index vol. 4 (3rd ed., 1971) p 4664.

Properties

Octahydrate, pink to blood-red, monoclinic, fine needles. On heating becomes anhydr by 400°. Dec by 1000° to Co6As2O11. d 2.9-3.1. Practically insol in water. Sol in dil mineral acids, in NH4OH.

Use

Painting on glass and porcelain.