About Chloroauric acid
Chloroauric acid is an orange-yellow crystal, easily deliquescent and soluble in water. Heat breaks down into gold. Chloroauric acid is the most common compound of gold. Chloroauric acid is widely used in analytical reagents and gold plating reagents.
After the reaction of pure gold and aqua regia through filtration and concentration, add concentrated hydrochloric acid to remove nitride, and then concentrate and crystallize the product. Anhydrous chloroauric acid (HAuCl) can be crystallized from ethanol solution.
Reaction equation: Au+HNO+4HCl=HAuCl+NO+2HO
In this reaction, the chloride ions in the concentrated hydrochloric acid combine with the gold coordination (4Cl +Au==(AuCl)) to make it easier to be oxidized, and then the N in the concentrated nitric acid oxidizes the coordinated gold to Au and reduces itself to N, (N +(AuCl) ==(AuCl) +N) and releases the extra O in the molecule. O combines with the excess hydrogen ions in concentrated hydrochloric acid to form HO, while N is released as NO.
Chloroauric acid reagents generally contain four crystalline waters, the chemical formula is AuCl·HCl·4HO, is golden yellow or orange needle crystal. The air is very deliquescent. Lose a water molecule in dry air. Soluble in water but also in alcohol and ether, slightly soluble in trichloromethane. It is corrosive and can leave purple spots on the skin. Anhydrous chloroauric acid can be crystallized from ethanol solution. Gold is generally dissolved in aqua regia to remove nitrogen compounds by evaporation.
Gold trichloride dissolves in concentrated hydrochloric acid to obtain chloroauric acid. It has been reported that gold powder dissolved in hydrogen peroxide-concentrated hydrochloric acid can also be used to prepare chloro auric acid safely and environmentally.
Chloro auric acid can be used for the gold plating of semiconductor and integrated circuit lead frames, printed circuit boards, electronic connectors and other electrical contact elements. Red glass can also be made. Used as an analytical reagent, especially for the microanalysis of rubidium and cesium and the measurement of alkaloid composition. Also used in photographic materials.