Come in, chemistry student.

Don't think that gold can't react directly with acid, or the so-called "real gold is not afraid of fire". The landlord thinks that gold has no compounds. In fact, gold can form many compounds, especially organic compounds. Many biological enzymes containing gold have many special physiological functions.

There are two kinds of gold hydroxide you ask: AuOH and Au(OH)3, usually Au(OH)3, which is a brown powdery solid and a hydrate of Au2O3, and can be dissolved in acid.

Other common gold compounds are:

1, aurous chloride AuCl

English name aurous chloride

Density 7.4

Character bright yellow crystal.

Dissolved in cold water, it is easy to dissolve and partially decompose, but completely decomposed in hot water.

The preparation or source is obtained by decomposing gold chloride at 65438 085℃ or thermally decomposing it in hydrogen chloride gas flow at 65438 075℃.

2. Gold chloride AuCl3

English name goldchlorine

The density is 3.9 g cm-3.

Melting point (℃)229

Character magenta prism crystal.

Soluble in water, ethanol and ether, insoluble in carbon disulfide.

Uses: Dyeing in black and white photography, gold plating in the manufacture of special ink, ceramics and glass.

Preparation or source: gold is dissolved in aqua regia, heated with concentrated hydrochloric acid to remove nitric acid, and dehydrated at 100℃ under vacuum.

Others begin to decompose at 254℃ and sublimate at 265℃. It is hygroscopic.

3. HAuCl4 hydrochloride

English name aurichlorohydric acid (hydrogen) chloroauric acid

Character orange crystal.

Soluble in water, ethanol and ether.

Used for photography and gold plating, as well as making special ink, red glass and gold powder.

The preparation or source is the effect of aqua regia on gold.

Other hygroscopicity is strong.

4. Potassium aurous cyanide; potassium dicyanoaurate

English name aurocyanide potassium; potassium dicyanoaurate

Density 3.42 (anhydrous)

Melting point (℃)200

White crystalline powder

Soluble in water, slightly soluble in ethanol, insoluble in ether.

Used for electroplating gold and chemical reagents.

This preparation or raw material can be obtained by the action of potassium cyanide on aurous chloride.

Everything else is highly toxic.

5. Gold cyanide

The density is 7.12g cm-3-3, and it is decomposed into cyanide and gold by heating.

6. Gold cyanide

Colorless flaky crystal, heated to 50℃ for decomposition.