Silver cyanide is a chemical compound with the formula AgCN. It is a white solid that precipitates upon treatment of solutions containing Ag + with cyanide , which is used in some schemes for the recovery of silver from solutions. Silver cyanide is used in silver-plating.
Its structure includes the – [Ag-CN] – chain in which the linear two-coordinate Ag + ions are bridged by cyanide ions, silver specific (I) and other d 10 ions. (This is the same binding mode as seen in the more famous case of light blue .) These chains are then packed hexagonally with adjacent chains by +/- 1/3 of the “c” lattice parameter. It is similar in structure to the high temperature polymorphism adopted by copper(I) cyanide . The carbon and silver to nitrogen bond lengths in AgCN are both ~2.09 [2] and the cyanide groups show head-to-tail disorder.
| Property | |
|---|---|
| chemical formula | AgCN |
| molar mass | 133.8856 g/mol |
| appearance | Colorless, gray (impure) crystals |
| dirt | odorless |
| density | 3.943 g/ cm3 |
| Melting point | 335 °C (635 °F; 608 K) (dissolved) |
| Solubility in water | 0.000023 g / 100 mL (20 ° C) |
| solubility | Soluble in concentrated ammonia , boiling nitric acid , ammonium hydroxide , KCN. insoluble in alcohol , dilute acid |
| Magnetic permeability (() | −43.2 10 −6 cm 3 / mol |
| refractive index ( n d ) | 1.685 |
| structure | |
| crystal structure | hexagonal |
| coordination geometry | linear |
reactions
AgCN is precipitated upon addition of sodium cyanide to the solution containing Ag + . The precipitate dissolves upon addition of further amounts of cyanide to form linear [Ag(CN) 2 ] − (aq) and [Ag(CN) 3 ] 2− (aq) upon further addition of cyanide. Silver cyanide is also soluble in solutions of other cations such as ammonia or tertiary phosphine .
Silver cyanides form structurally complex materials upon reaction with other ions. Some silver cyanides are luminescent .
Use
Both AgCN and KAg(CN) 2 have been used in silver-plating solutions since at least 1840 when the Elkington brothers patented their recipe for silver-plating solutions. A typical, traditional silver-plating solution would contain 15–40 g L −1 KAg (CN) 2 , 12–120 g L −1 KCN and 15 g L −1 K 2 CO 3 .
Observation
Silver cyanide is a chemical compound with the formula AgCN. This white solid is formed upon treatment of a solution of cyanide containing Ag. This precipitation step is used in some schemes to remove silver from the solution. Silver cyanide is used in silver plating.
Chemical formula AgCN. When sodium cyanide NaCN or potassium cyanide KCN is added to an aqueous solution of silver nitrate AgNO 3 at a slightly insufficient level, a white powdery precipitate is obtained . It is stable in dry air , but gradually darkens due to light . On heating it decomposes at 320 °C before melting. Relative density 3.95. In crystals , it is a multiple of bounded straight lines like -Ag-C≡N-Ag-C≡N-. It is believed that the Ag-C bond in the above structure is stronger than the Ag-N bond.This is because the reaction of alkyl halides mainly produces isonitrile RNCs. Solubility in water 2 × 10 6 mol / l (25 ° C). Insoluble in alcohol but soluble in pyridine. This alkali metal cyanide produces complex ions such as [Ag(OH)(CN)] 2 , [Ag(CN) 2 ] , and [Ag(CN) 3 ] 2 and dissolves well in aqueous solutions of alkali metals. toxic substance.
kunihiko mizumachi
