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oxidized gold?


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has anyone seen oxidized gold? if so could you post a picture? guy said it was but it looked like yellow quartz to me. :idunno:

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  Gold does Not Oxidize as per say like Rust or Tarnish.   It can be Restated !  That is to put it in a Oxidized State.



Gold(III) chloride solution in water

Although gold is the most noble of the noble metals,[31][32] it still forms many diverse compounds. The oxidation state of gold in its compounds ranges from −1 to +5, but Au(I) and Au(III) dominate its chemistry. Au(I), referred to as the aurous ion, is the most common oxidation state with soft ligands such as thioethers, thiolates, and tertiary phosphines. Au(I) compounds are typically linear. A good example is Au(CN)2, which is the soluble form of gold encountered in mining. The binary gold halides, such as AuCl, form zigzag polymeric chains, again featuring linear coordination at Au. Most drugs based on gold are Au(I) derivatives.[33]

Au(III) (auric) is a common oxidation state, and is illustrated by gold(III) chloride, Au2Cl6. The gold atom centers in Au(III) complexes, like other d8 compounds, are typically square planar, with chemical bonds that have both covalent and ionic character.

Gold does not react with oxygen at any temperature[34] and, up to 100 °C, is resistant to attack from ozone.[35]

Some free halogens react with gold.[36] Gold is strongly attacked by fluorine at dull-red heat[37] to form gold(III) fluoride. Powdered gold reacts with chlorine at 180 °C to form AuCl3.[38] Gold reacts with bromine at 140 °C to form gold(III) bromide, but reacts only very slowly with iodine to form the monoiodide.

Gold does not react with sulfur directly,[39] but gold(III) sulfide can be made by passing hydrogen sulfide through a dilute solution of gold(III) chloride or chlorauric acid.

Gold readily dissolves in mercury at room temperature to form an amalgam, and forms alloys with many other metals at higher temperatures. These alloys can be produced to modify the hardness and other metallurgical properties, to control melting point or to create exotic colors.[25]

Gold reacts with potassium, rubidium, caesium, or tetramethylammonium, to form the respective auride salts, containing the Au ion. Caesium auride is perhaps the most famous.

Gold is unaffected by most acids. It does not react with hydrofluoric, hydrochloric, hydrobromic, hydriodic, sulfuric, or nitric acid. It does react with selenic acid, and is dissolved by aqua regia, a 1:3 mixture of nitric acid and hydrochloric acid. Nitric acid oxidizes the metal to +3 ions, but only in minute amounts, typically undetectable in the pure acid because of the chemical equilibrium of the reaction. However, the ions are removed from the equilibrium by hydrochloric acid, forming AuCl4 ions, or chloroauric acid, thereby enabling further oxidation.

Gold is similarly unaffected by most bases. It does not react with aqueous, solid, or molten sodium or potassium hydroxide. It does however, react with sodium or potassium cyanide under alkaline conditions when oxygen is present to form soluble complexes.[39]

Common oxidation states of gold include +1 (gold(I) or aurous compounds) and +3 (gold(III) or auric compounds). Gold ions in solution are readily reduced and precipitated as metal by adding any other metal as the reducing agent. The added metal is oxidized and dissolves, allowing the gold to be displaced from solution and be recovered as a solid precipitate.

Rare oxidation states

Less common oxidation states of gold include −1, +2, and +5.

The −1 oxidation state occurs in compounds containing the Auanion, called aurides. Caesium auride (CsAu), for example, crystallizes in the caesium chloride motif.[40] Other aurides include those of Rb+, K+, and tetramethylammonium (CH3)4N+.[41] Gold has the highest Pauling electronegativity of any metal, with a value of 2.54, making the auride anion relatively stable.

Gold(II) compounds are usually diamagnetic with Au–Au bonds such as [Au(CH2)2P(C6H5)2]2Cl2. The evaporation of a solution of Au(OH)
in concentrated H
produces red crystals of gold(II) sulfate, Au2(SO4)2. Originally thought to be a mixed-valence compound, it has been shown to contain Au4+
cations, analogous to the better-known mercury(I) ion, Hg2+
.[42][43] A gold(II) complex, the tetraxenonogold(II) cation, which contains xenon as a ligand, occurs in [AuXe4](Sb2F11)2.[44]

Gold pentafluoride, along with its derivative anion, AuF
, and its difluorine complex, gold heptafluoride, is the sole example of gold(V), the highest verified oxidation state.[45]

Some gold compounds exhibit aurophilic bonding, which describes the tendency of gold ions to interact at distances that are too long to be a conventional Au–Au bond but shorter than van der Waals bonding. The interaction is estimated to be comparable in strength to that of a hydrogen bond.

Well-defined cluster compounds are numerous.[41] In such cases, gold has a fractional oxidation state. A representative example is the octahedral species {Au(P(C6H5)3)}62+. Gold chalcogenides, such as gold sulfide, feature equal amounts of Au(I) and Au(III).

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 :goodpost: Excellent post, Homie.  That's exactly what I was going to post. ... word for word...    No really I was ;p

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