Silver cyanide

Physical Properties

Grayish-white hexagonal crystals; decomposes at 320°C; insoluble in water, alcohol or dilute acids; moderately soluble in concentrated ammonia; soluble in concentrated boiling nitric acid; also soluble in alkali cyanide solutions.

Preparation

Silver cyanide is prepared by adding a solution of an alkali cyanide to a solution of silver nitrate:
Ag+ (aq) + CN¯ (aq) → AgCN (s)

Chemical Properties

white to off-white powder

Chemical Properties

Silver cyanide is a white or grayish, odorless powder which darkens when exposed to light.

Physical properties

Grayish-white hexagonal crystals; density 3.95 g/cm³; decomposes at 320°C; insoluble in water, alcohol or dilute acids; moderately soluble in concentrated ammonia; soluble in concentrated boiling nitric acid; also soluble in alkali cyanide solutions.

Uses

Silver cyanide is used in silver-plating.

Uses

For silver plating; formerly used for extemporaneous preparation of dil hydrocyanic acid by treatment with HCl.

General Description

A white to gray odorless tasteless powder that darkens on exposure to light. Insoluble in water. Toxic by skin absorption through open wounds, ingestion and inhalation of dust. Toxic oxides of nitrogen are produced in fires.

Air & Water Reactions

Insoluble in water. Decomposes slowly when moist, giving off hydrogen cyanide, which is toxic by inhalation.

Reactivity Profile

Silver cyanide is very rapidly decomposed by acids giving off hydrogen cyanide, a flammable poison gas. Soluble in aqueous ammonia, dilute boiling nitric acid, aqueous potassium cyanide solution and aqueous sodium thiosulfate solutions. Subject to explosive instability or violent oxidation under certain conditions. Fusion with metal chlorates, perchlorates, nitrates, or nitrites can cause a violent explosion [Bretherick 1979 p. 101]. Fluorine and Silver cyanide react with explosive violence at ordinary temperatures [Mellor 2 Supp. 1:63 1956].

Hazard

Toxic by ingestion or inhalation.

Health Hazard

Highly toxic, may be fatal if inhaled, swallowed or absorbed through skin. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.
LD50 oral (rat): 123mg/kg

Fire Hazard

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Containers may explode when heated. Runoff may pollute waterways.

Flammability and Explosibility

Not classified

Safety Profile

Deadly poison by ingestion. A skin and severe eye irritant. When heated to decomposition it emits very toxic fumes of CNand NO,. Incompatible with phosphorus tricyanide, fluorine. Used in silver plating. See also SILVER COMPOUNDS and CYANIDE.

Potential Exposure

It is primarily used in silver plating.

Shipping

UN1684 Silver cyanide, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Purification Methods

It is a POISONOUS white or grayish white powder. Stir it thoroughly with H2O, filter, wash well with EtOH and dry it in air in the dark. It is very insoluble in H2O (0.000023g in 100mL H2O) but is soluble in HCN or aqueous KCN to form the soluble Ag(CN) 22
complex. [Schnitz-Dumont Chem Ber 72 298 1939, Randall & Halford J Am Chem Soc 52 184 1930.]

Incompatibilities

Acetylene, ammonia, and hydrogen peroxide (H2O2). Contact with moisture, CO2, acid and acid fumes release hydrogen cyanide. Contact with fluorine is violently explosive at normal temperatures. Incompatible with phosphorus cyanide.

Waste Disposal

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform to EPA regulations governing storage, transportation, treatment, and waste disposal

Raw materials

Preparation Products