Chemical Properties
yellow powder(s); hexagonal; odorless; iridescent in sunlight; slowly decomposes in presence of moisture [MER06]
Physical properties
Yellow hexagonal crystals; odorless; density 7.14 g/cm
3; decomposes slowly in the presence of moisture or decomposes on heating; insoluble in water, alcohol and ether; also insoluble in dilute acids; soluble in aqueous solutions of potassium-, or sodium cyanide, ammonia, and aqua regia.
Uses
Electrolyte in the electroplating industry
Preparation
Gold(I) cyanide may be prepared by boiling sodium aurus cyanide, Na[Au(CN)
2] with hydrochloric acid:Na[Au(CN)2] + HCl AuCN + HCN + NaCl
The complex cyanide, Na[Au(CN)
2] is made by dissolving gold in a dilute solution of sodium cyanide in the presence of air; or by dissolution of a gold anode in a solution of sodium cyanide during electrolysis. The solution is evaporated to separate the complex, Na[Au(CN)
2], which is purified by recrystallization from water. Potassium cyanide may be used instead of sodium cyanide to prepare gold(I) cyanide.
Purification Methods
The lemon yellow powder is sparingly soluble in H2O and EtOH but soluble in aqueous NH3. It is obtained by heating H[Au(CN)2] at 110o. Wash it well with H2O and EtOH and dry it at 110o. It has an IR band at max 2239 cm -1 typical for C stretching vibration. [Glemser & Sauer Handbook of Preparative Inorg anic Chemistry (Ed. Brauer) Academic Press Vol II p 1064 1965.] CARE: may evolve HCN.
