Antimony pentoxide (molecular formula: Sb2O5) is a
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
of
antimony
Antimony is a chemical element with the symbol Sb (from la, stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient t ...
and
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
. It contains antimony in the +5
oxidation state
In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...
.
Structure
Antimony pentoxide has the same structure as the ''B'' form of
niobium pentoxide
Niobium pentoxide is the inorganic compound with the formula Nb2 O5. A colorless, insoluble, and fairly unreactive solid, it is the most widespread precursor for other compounds and materials containing niobium. It is predominantly used in alloyi ...
and can be derived from the
rutile
Rutile is an oxide mineral composed of titanium dioxide (TiO2), the most common natural form of TiO2. Rarer polymorphs of TiO2 are known, including anatase, akaogiite, and brookite.
Rutile has one of the highest refractive indices at visib ...
structure, with antimony coordinated by six oxygen atoms in a distorted octahedral arrangement. The SbO6 octahedra are corner- and edge-sharing.
hydrolysis
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.
Biological hydrolys ...
of
antimony pentachloride
Antimony pentachloride is a chemical compound with the formula SbCl5. It is a colourless oil, but typical samples are yellowish due to dissolved chlorine. Owing to its tendency to hydrolyse to hydrochloric acid, SbCl5 is a highly corrosive substa ...
nitric acid
Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...
.
Uses
Antimony pentoxide finds use as a
flame retardant
The term flame retardants subsumes a diverse group of chemicals that are added to manufactured materials, such as plastics and textiles, and surface finishes and coatings. Flame retardants are activated by the presence of an ignition source and ...
in ABS and other plastics and as a flocculant in the production of
titanium dioxide
Titanium dioxide, also known as titanium(IV) oxide or titania , is the inorganic compound with the chemical formula . When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or CI 77891. It is a white solid that is insolub ...
, and is sometimes used in the production of glass, paint and adhesives.
It is also used as an ion exchange resin for a number of cations in acidic solution including Na+ (especially for their selective retentions), and as a
polymerization
In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many fo ...
and
oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
catalyst.
Properties and reactions
The hydrated oxide is insoluble in nitric acid, but dissolves in a concentrated
potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash.
Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exp ...
solution to give potassium hexahydroxoantimonate(V), or KSb(OH)6.
When heated to , the yellow hydrated pentoxide converts to an anhydrous white solid with the formula Sb6O13, containing both antimony(III) and antimony(V). Heating to produces a white, insoluble powder of Sb2O4 in both α and β forms. The β form consists of antimony(V) in octahedral interstices and pyramidal SbIIIO4 units. In these compounds, the antimony(V) atom is octahedrally coordinated to six hydroxy groups.
The pentoxide can be reduced to antimony metal by heating with
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
or potassium cyanide."Antimony" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 606.