Silver oxide
| Silver oxide | |
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Silver(I) oxide |
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Other names
Silver rust, Argentous oxide |
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| Identifiers | |
| CAS number | 20667-12-3  |
| RTECS number | VW4900000 |
| Properties | |
| Molecular formula | Ag2O |
| Molar mass | 231.735 g/mol |
| Appearance | black/brown cubic crystals |
| Density | 7.14 g/cm3 |
| Melting point |
280 °C (decomposition) |
| Solubility in water | 0.025 g/L[1] |
| Solubility product, Ksp of AgOH | 1.52×10−8 (20 °C) |
| Solubility | soluble in acid, alkali insoluble in alcohol, ethanol[1] |
| Structure | |
| Crystal structure | cubic |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
−31 kJ·mol−1[2] |
| Standard molar entropy S |
122 J·mol−1·K−1[2] |
| Specific heat capacity, C | 65.9 J·mol−1·K−1[3] |
| Hazards | |
| MSDS | Material Safety Data Sheet |
| Related compounds | |
| Related compounds | silver(I,III) oxide, AgO |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Silver(I) oxide is the chemical compound with the formula Ag2O. It is a fine black or dark brown powder that is used to prepare other silver compounds.
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[edit] Preparation
Silver oxide is commercially available. It can be easily prepared by combining aqueous solutions of silver nitrate and an alkali hydroxide.[4] Noteworthy is the fact that this reaction does not afford appreciable amounts of silver hydroxide due to the favorable energetics for the following reaction:[5]
[edit] Structure and properties
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Like most binary oxides, Ag2O is a three-dimensional polymer with covalent metal-oxygen bonding. It is isostructural with Cu2O. It is therefore expected that Ag2O is insoluble in all solvents,[7] except by reaction. It is also slightly soluble in aqueous solution due to the formation of the ion, Ag(OH)2– and possibly related hydrolysis products.[8] It dissolves in ammonia solution to give soluble derivatives.[citation needed] A slurry of Ag2O is readily attacked by acids:
- Ag2O + 2 HX → 2 AgX + H2O
where HX = HF, HCl, HBr, or HI, HO2CCF3. It will also react with solutions of alkali chlorides to precipitate silver chloride, leaving a solution of the corresponding alkali hydroxide.[9][8]
Like many silver compounds, silver oxide is photosensitive. It also decomposes at temperatures above 280 °C.[7]
[edit] Applications
Commercially, silver oxide is used in a silver-oxide battery. In organic chemistry, silver oxide is used as a mild oxidizing agent. For example it oxidizes aldehydes to carboxylic acids. Such reactions often work best when the silver oxide is prepared in situ from silver nitrate and alkali hydroxide.
[edit] References
- ^ a b Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, FL: CRC Press. pp. 4–83. ISBN 0-8493-0594-2.
- ^ a b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed.. Houghton Mifflin Company. p. A23. ISBN 061894690X.
- ^ Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, FL: CRC Press. pp. 5–5. ISBN 0-8493-0594-2.
- ^ Janssen, D. E.; Wilson, C. V. (1963), "4-Iodoveratrole", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV4P0547; Coll. Vol. 4: 547
- ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- ^ Biedermann, George; Sillén, Lars Gunnar (1960). "Studies on the Hydrolysis of Metal Ions. Part 30. A Critical Survey of the Solubility Equilibria of Ag2O". Acta Chemica Scandinavica 14: 717. doi:10.3891/acta.chem.scand.14-0717.
- ^ a b Merck Index of Chemicals and Drugs, 14th ed. monograph 8521
- ^ a b Cotton, F. Albert; Wilkinson, Geoffrey (1966). Advanced Inorganic Chemistry (2nd Ed.). New York:Interscience. p. 1042.
- ^ General Chemistry by Linus Pauling, 1970 Dover ed. p703-704
[edit] External links
- Annealing of Silver Oxide Demonstration experiment: Instruction and video
- Silver Oxide, Ag2O
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