8 julio, 2024

Tin(II) oxide: structure, properties, nomenclature, uses

He tin(II) oxide It is a crystalline inorganic solid that is formed by the oxidation of tin (Sn) by oxygen, where tin acquires a valence of 2+. Its chemical formula is SnO. Two different forms of this compound are known: the black and the red. The common and most stable form at room temperature is the black or bluish-black modification.

This form is prepared by hydrolysis of tin(II) chloride (SnCl2) in aqueous solution, to which ammonium hydroxide (NH4OH) is added to obtain a hydrated Sn(II) oxide precipitate whose formula is SnO.xH2O , where x<1 (x less than 1).

The hydrated oxide is a white amorphous solid, which is then heated in suspension at 60-70 ºC for several hours in the presence of NH4OH, until pure black crystalline SnO is obtained.

The red form of SnO is metastable. It can be prepared by adding phosphoric acid (H3PO4) – with 22% phosphorous acid, H3PO3 – and then NH4OH to a SnCl2 solution. The white solid obtained is heated in the same solution at 90-100 ºC for about 10 minutes. In this way, pure red crystalline SnO is obtained.

Tin(II) oxide is a starting material for the production of other tin(II) compounds. For this reason, it is one of the tin compounds that has appreciable commercial importance.

Tin(II) oxide has low toxicity as occurs with most inorganic tin compounds. This is due to its poor absorption and rapid excretion from the tissues of living beings.

It has one of the highest tolerances of tin compounds in rat tests. However, it can be harmful if inhaled in large amounts.

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Structure

Tin(II) oxide bluish-black

This modification crystallizes with a tetragonal structure. It has a layered arrangement in which each Sn atom sits at the top of a square pyramid, the base of which is formed by the 4 closest oxygen atoms.

Other researchers state that each Sn atom is surrounded by 5 oxygen atoms that are located approximately at the vertices of an octahedron, with the sixth vertex presumably occupied by a lone or unpaired pair of electrons. This is known as the Φ-octahedral arrangement.

Tin(II) oxide red

This form of tin(II) oxide crystallizes with an orthorhombic structure.

Nomenclature

– Tin(II) oxide

– Tin oxide

– Tin monoxide

– Stannous oxide

Properties

physical state

crystalline solid.

Molecular weight

134.71 g/mol.

Melting point

1080ºC It decomposes.

Density

6.45g/cm3

Solubility

Insoluble in cold or hot water. Insoluble in methanol, but dissolves rapidly in concentrated acids and alkalis.

other properties

If heated to more than 300 ºC in the presence of air, tin(II) oxide oxidizes rapidly to tin(IV) oxide, presenting incandescence.

It has been reported that under non-oxidizing conditions, heating tin(II) oxide has different results depending on the degree of purity of the starting oxide. It generally disproportionates into metallic Sn and tin(IV) oxide, SnO2, with various intermediate species eventually converted to SnO2.

Tin(II) oxide is amphoteric, dissolving in acids to give Sn2+ ions or anion complexes, and also dissolving in alkalis to form solutions of hydroxy-tin ions, Sn(OH)3which have a pyramidal structure.

Furthermore, SnO is a reducing agent and rreacts rapidly with organic and mineral acids.

It has low toxicity when compared to other tin salts. Its LD50 (50% lethal dose or median lethal dose) in rats is more than 10,000 mg/Kg. This means that more than 10 grams per kilogram is required to kill 50% of the rat specimens under a given test period. In comparison, tin(II) fluoride has an LD50 of 188 mg/kg in rats.

However, if it is inhaled for a long time, it is deposited in the lungs because it is not absorbed and can cause stannosis (infiltration of SnO dust into the lung interstices).

Applications

In the production of other tin(II) compounds

Its rapid reaction with acids is the basis of its most important use, which is as an intermediate in the manufacture of other tin compounds.

It is used in the production of tin (II) bromide (SnBr2), tin (II) cyanide (Sn(CN)2) and tin (II) fluoroborate hydrate (Sn(BF4)2), among other compounds. of tin(II).

Tin(II) fluoroborate is prepared by dissolving SnO in fluoroboric acid and is used for tin and tin-lead coatings, especially in the deposition of tin-lead alloys for soldering in the electronics industry. This is due, among other things, to its high coverage capacity.

Tin(II) oxide is also used in the preparation of tin(II) sulfate (SnSO4), by the reaction of SnO and sulfuric acid, H2SO4.

The SnSO4 obtained is used in the tinning process for the production of printed circuit boards, for finishing electrical contacts and for tinning kitchen utensils.

The hydrated form of SnO, hydrated tin(II) oxide SnO.xH2O, is treated with hydrofluoric acid to obtain tin(II) fluoride, SnF2, which is added to toothpastes as a caries-fighting agent.

in jewelry

Tin(II) oxide is used in the preparation of gold-tin and copper-tin ruby ​​crystals. Apparently its function in this application is to act as a reducing agent.

Other uses

It has been used in photovoltaic devices for the production of electricity from light, such as solar cells.

recent innovations

Ordered SnO nanoparticles have been used in carbon nanotube electrodes for lithium-sulfur batteries.

Electrodes prepared with SnO exhibit high conductivity and little volume change under repetitive charge and discharge cycles.

In addition, SnO facilitates rapid ion/electron transfer during oxidation-reduction reactions that occur in such battery systems.

References

Cotton, F. Albert and Wilkinson, Geoffrey. (1980). Advanced Inorganic Chemistry. fourth edition. John Wiley & Sons.
Dance, JC; Emeleus, HJ; Sir Ronald Nyholm and Trotman-Dickenson, AF (1973). Comprehensive Inorganic Chemistry. Volume 2. Pergamon Press.
Ullmann’s Encyclopedia of Industrial Chemistry. (1990). fifth edition. Volume A27. VCH Verlagsgesellschaft mbH.
Kirk-Othmer (1994). Encyclopedia of Chemical Technology. Volume 24. Fourth Edition. John Wiley & Sons.
Ostrakhovitch, Elena A. and Cherian, M. George. (2007). tin. In Handbook of the Toxicology of Metals. Third Edition. Retrieved from sciencedirect.com.
Kwestroo, W. and Vromans, PHGM (1967). Preparation of Three Modifications of Pure Tin (II) Oxide. J.Inorg. Nucl. Chem., 1967, Vol.29, pp.2187-2190.
Fouad, SS et al. (1992). Optical properties of stannous oxide thin films. Czechoslovak Journal of Physics. February 1992, Volume 42, Issue 2. Retrieved from springer.com.
A-Young Kim et al. (2017). Ordered SnO nanoparticles in MWCNT as a functional host material for high-rate lithium-sulphur battery cathode. Nano Research 2017, 10(6). Recovered from springer.com.
National Library of Medicine. (2019). Stannous oxide. Retrieved from: pubchem.ncbi.nlm.nih.gov

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