Gold(III) hydroxide, gold trihydroxide, or gold hydroxide is an inorganic compound, a

hydroxide Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. I ...

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile me ...

, with formula Au(OH)₃. It is also called auric acid with formula H₃AuO₃. It is easily dehydrated above 140 °C to gold(III) oxide. Salts of auric acid are termed aurates. Gold hydroxide is used in medicine,

porcelain Porcelain () is a ceramic material made by heating substances, generally including materials such as kaolinite, in a kiln to temperatures between . The strength and translucence of porcelain, relative to other types of pottery, arises main ...

making,

gold plating Gold plating is a method of depositing a thin layer of gold onto the surface of another metal, most often copper or silver (to make silver-gilt), by chemical or electrochemical plating. This article covers plating methods used in the modern elec ...

, and

daguerrotype Daguerreotype (; french: daguerréotype) was the first publicly available photography, photographic process; it was widely used during the 1840s and 1850s. "Daguerreotype" also refers to an image created through this process. Invented by Loui ...

s. Gold hydroxide deposited on suitable carriers can be used for preparation of gold

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

s. Gold hydroxide is a product of electrochemical

corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engi ...

of gold metalization subjected to moisture and positive electric potential; it is one of the corrosion failure modes of

microelectronics Microelectronics is a subfield of electronics. As the name suggests, microelectronics relates to the study and manufacture (or microfabrication) of very small electronic designs and components. Usually, but not always, this means micrometre-s ...

. Voluminous gold hydroxide is produced from gold metalization; after the layer grows thick it may

spall Spall are fragments of a material that are broken off a larger solid body. It can be produced by a variety of mechanisms, including as a result of projectile impact, corrosion, weathering, cavitation, or excessive rolling pressure (as in a ba ...

, and the conductive particles may cause short circuits or leakage paths. The decreased thickness of the gold layer may also lead to an increase in its electrical resistance, which can also lead to electrical failure.

Preparation and reactions

Gold(III) hydroxide is produced by the reaction of

chloroauric acid Chloroauric acid is an inorganic compound with the chemical formula . It forms hydrates . Both the trihydrate and tetrahydrate are known. Both are orange-yellow solids consisting of the planar anion. Often chloroauric acid is handled as a soluti ...

with an alkali, such as sodium hydroxide: :HAuCl₄ + 4NaOH → Au(OH)₃ + 4NaCl + H₂O Gold(III) hydroxide reacts with ammonia to produce

fulminating gold Fulminating gold is a light- and shock-sensitive yellow to yellow-orange amorphous heterogeneous mixture of different polymeric compounds of predominantly gold (III), ammonia, and chlorine that cannot be described by a chemical formula. Here, the ...

, an explosive compound.

References

Gold(III) compounds Hydroxides {{Inorganic-compound-stub