Chloroauric acid | |
---|---|
Other names
Hydrogen tetrachloroaurate, |
|
Identifiers | |
CAS number | 16903-35-8 |
ChemSpider | 26171 |
Jmol-3D images | Image 1 |
|
|
|
|
Properties | |
Molecular formula | HAuCl4 |
Molar mass | 339.785 g/mol (anhydrous) 393.833 g/mol (trihydrate) 411.85 g/mol (tetrahydrate) |
Appearance | golden yellow crystals hygroscopic |
Density | 3.9 g/cm3 (tetrahydrate) |
Melting point |
254°C |
Solubility in water | soluble |
Solubility | soluble in alcohol, ether |
Related compounds | |
Other anions | Tetrabromoauric acid |
(verify) (what is: / ?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
|
Infobox references |
Chloroauric acid is a inorganic compound with the formula HAuCl4. This pale yellow compound is a common precursor to gold (Au) in a variety of purposes. The term chloroauric acid is also sometimes used to describe other gold chlorides.
Contents |
Chloroauric acid is obtained by dissolving gold in aqua regia followed by evaporation of these solutions.[1] Upon heating, chloroauric acid liberates hydrogen chloride, giving gold(III) chloride. This reaction is reversible: dissolving gold(III) chloride in hydrochloric acid:
In aqueous solution, chloroauric acid consists of the square planar [AuCl4]− ion. It is a common precursor to other gold coordination complexes.[2]
Chloroauric acid is readily reduced by most metals to precipitate elemental gold.
This compound is reduced by dimethyl sulfide to give chloro(dimethyl sulfide)gold(I), which is also useful as a precursor to other gold complexes.[3]
Chloroauric acid is used as the electrolyte in the Wohlwill process for refining gold.
Generally, colloidal gold and gold nanoparticles are produced in a solution ("liquid chemical methods") by reduction of chloroauric acid with trisodium citrate, although alternative methods exist, such as the Norrish reaction and the aldehyde reduction used in Angel gilding.
|