Cobalt(II) oxide

Template:Chembox header | Cobalt(II) oxide
Cobalt(II) oxide
Template:Chembox header | General
Systematic name	Cobalt(II) Oxide
Other names	Cobaltous Oxide, Cobalt Monoxide, Cobaltous Monoxide
Molecular formula	CoO
Molar mass	74.93 g/mol
Appearance	A grayish green powder
CAS number	1307-96-6
Template:Chembox header | Properties
Density and phase	6.1 g/cm3
Solubility in water	practically insoluble in water, soluble in strong acids
Melting point	1933°C (2206 K)
Boiling point	?°C (? K)
Template:Chembox header | Hazards
MSDS	(Use CAS#) Fisher Scientific
Main hazards	Respiratory tract inflammation possibly carcinogenic
NFPA 704	Template:NFPA 704
R/S statement	R: 22 43 50-53 S: (2-)24-37-60-61
RTECS number	GG2800000
Template:Chembox header | Related compounds
Other anions	Cobalt(II) carbonate Cobalt(II) nitrate, Cobalt(II) chloride
Other cations	Iron(III) oxide, Iron(II) oxide Cobalt(II,III) oxide
Related compounds	Cobalt(III) oxide
Template:Chembox header | Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references

Cobalt(II) oxide is a grayish green powder used extensively in the ceramics industry as an additive to create blue colored glazes and enamels as well as in the chemical production industry for producing cobalt(II) salts.

Cobalt(II) oxide is a product of Cobalt(II,III) oxide decomposing at 895 °C through the reaction:

2 Co₃O_4(s) → 6 CoO_(s) + O_2(g)

Cobalt(II) oxide is also a product of Cobalt(II) carbonate decomposing when heated through the reaction:

CoCO_3(s) → CoO_(s) + CO_2(g)

Ceramics and Other Uses

Cobalt(II) oxide has been used for centuries as a coloring agent on kiln fired ceramic glazes, the earliest examples go back to the beginnings of kiln fired pottery. Cobalt(II) oxide colorants are stable and retain their coloration indefinitely. The oxide is one of the most powerful colorants commonly used in the making of glazes and slips and requires only 1 part oxide to 100,000 parts glazing compound to produce the deep blue shade commonly referred to as cobalt blue. By varying the temperature of the kiln, the potter can adjust the coloring of the oxide ranging anywhere from the familiar blue, to a shade nearing black. Cobalt(II) oxide is also used in dryers used with oil based paints to expedite their curing. These substances can be found at most art stores.

Industrial Uses

As stated earlier, cobalt(II) oxide is used in the production of cobalt(II) salts such as CoCl₂ and Co(NO₃)₂. Cobalt(II) oxide can also be found in animal feed and fertilizer as a supplement to aid in the production of Vitamin B12.

Health Concerns

This oxide is also found in cobalt dryers, additives to paints that can be found at most art stores. These dryers are considered highly toxic and a "possible human carcinogen" by the International Agency for Research on Cancer. Symptoms of acute exposure include coughing, wheezing and difficulty breathing. The small particles also pose the risk of ocular inflammation. The use of NFPA/NIOSH approved respiratory equipment is recommended when handling this substance.

Toxicology

LD50/LC50 tests indicate that in rats a dose of 202mg per kilogram given orally is fatal. In 1992 the State of California added Cobalt(II) oxide to its list of carcinogenic agents however RTECS does not officially list the oxide as a carcinogen.

Reactivity Concerns

Cobalt(II) oxide rapidly decomposes hydrogen peroxide and oxidizes the drying of unsaturated oils in an exothermic reaction that can be potentially explosive.