stannous oxide
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Tin(II) oxide (stannous oxide) is a compound with the formula SnO. It is composed of
tin Tin is a with the Sn (from la, ) and  50. Tin is a silvery-colored metal that characteristically has a faint yellow hue. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent ...

tin
and
oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

oxygen
where tin has the oxidation state of +2. There are two forms, a stable blue-black form and a
metastable In chemistry and physics, metastability denotes an intermediate energetic state within a dynamical system other than the system's ground state, state of least energy. A ball resting in a hollow on a slope is a simple example of metastability. I ...

metastable
red form.


Preparation and reactions

Blue-black SnO can be produced by heating the tin(II) oxide hydrate, SnO·xH2O (x<1) precipitated when a tin(II) salt is reacted with an alkali hydroxide such as NaOH.Egon Wiberg, Arnold Frederick Holleman (2001) ''Inorganic Chemistry'', Elsevier
Metastable, red SnO can be prepared by gentle heating of the precipitate produced by the action of aqueous ammonia on a tin(II) salt.
SnO may be prepared as a pure substance in the laboratory, by controlled heating of tin(II) oxalate ( stannous oxalate) in the absence of air or under a CO2 atmosphere. This method is also applied to the production of
ferrous oxide Iron(II) oxide or ferrous oxide is the inorganic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structur ...
and
manganous oxide Manganese(II) oxide is an inorganic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties ...
. :SnC2O4·2H2O → SnO + CO2 + CO + 2 H2O Tin(II) oxide burns in air with a dim green flame to form SnO2. :2 SnO + O2 → 2 SnO2 When heated in an inert atmosphere initially
disproportionation In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds composed of atoms, mo ...

disproportionation
occurs giving Sn metal and Sn3O4 which further reacts to give SnO2 and Sn metal. :4SnO → Sn3O4 + Sn :Sn3O4 → 2SnO2 + Sn SnO is
amphoteric In chemistry, an amphoteric compound is a molecule or ion that can react both as an acid An acid is a or capable of donating a (hydrogen ion H+) (a ), or, alternatively, capable of forming a with an (a ). The first category of acids a ...

amphoteric
, dissolving in strong acid to give tin(II) salts and in strong base to give stannites containing Sn(OH)3. It can be dissolved in strong acid solutions to give the ionic complexes Sn(OH2)32+ and Sn(OH)(OH2)2+, and in less acid solutions to give Sn3(OH)42+. Note that anhydrous stannites, e.g. K2Sn2O3, K2SnO2 are also known. SnO is a reducing agent and is thought to reduce copper(I) to metallic clusters in the manufacture of so-called "copper ruby glass".


Structure

Black, α-SnO adopts the tetragonal PbO layer structure containing four coordinate square pyramidal tin atoms. This form is found in nature as the rare mineral romarchite. The asymmetry is usually simply ascribed to a sterically active lone pair; however, electron density calculations show that the asymmetry is caused by an antibonding interaction of the Sn(5s) and the O(2p) orbitals. The electronic structure and chemistry of the lone pair determines most of the properties of the material. Non-stoichiometry has been observed in SnO. The electronic band gap has been measured between 2.5 eV and 3eV.


Uses

The dominant use of stannous oxide is as a precursor in manufacturing of other, typically divalent, tin compounds or salts. Stannous oxide may also be employed as a reducing agent and in the creation of ruby glass. It has a minor use as an
esterification An ester is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together by chemic ...

esterification
catalyst.
Cerium(III) oxide Cerium(III) oxide, also known as cerium oxide, cerium trioxide, cerium sesquioxide, cerous oxide or dicerium trioxide, is an oxide of the rare-earth metal The rare-earth elements, also called the rare-earth metals or (in context) rare-earth ...
in
ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant Corrosion is a Erosion, natural process that converts a refined metal into a more chemically stable form such as oxide, hydroxide, carbonate or sulfide. ...

ceramic
form, together with Tin(II) oxide (SnO) is used for illumination with UV light.


References

{{Oxides Amphoteric compounds Oxides Reducing agents Tin compounds