Calcium cyanide
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| Names | |
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IUPAC name
calcium dicyanide
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Systematic IUPAC name
calcium dicyanide
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| Identifiers | |
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.008.856 |
| EC Number | 209-740-0 |
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PubChem CID
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| Properties | |
| Ca(CN)2 | |
| Molar mass | 92.1128 g/mol |
| Appearance | white powder |
| Odor | hydrogen cyanide |
| Density | 1.853 (20 °C) |
| Melting point | 640 °C (1,184 °F; 913 K) (decomposes) |
| soluble | |
| Solubility | soluble in alcohol, weak acids |
| Structure | |
| rhombohedric | |
| Hazards | |
| NFPA 704 | |
| Non-flammable | |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Infobox references | |
Calcium cyanide also known as black cyanide, is an inorganic compound with the formula Ca(CN)2. It is a white solid, although it is rarely observed in pure form. Commercial samples can be black-gray. It is the calcium salt of cyanide. It hydrolyses readily (even on moist air) to release hydrogen cyanide. Like other similar cyanides it is very toxic.
Calcium cyanide can be prepared by treating powdered calcium oxide with boiling anhydrous hydrocyanic acid in the presence of an accelerator such as ammonia or water in order to minimize the loss of the hydrocyanic acid by polymerization. It may also be prepared by reacting liquid hydrocyanic acid with calcium carbide. Alternatively calcium cyanide may be prepared by reacting hydrocyanic acid gas with quicklime (CaO) at high temperatures around 400 °C. At higher temperatures around 600 °C calcium cyanimide is formed instead. The material prepared often is contaminated with polymeric derivatives of hydrogen cyanide, hence the black color.
Calcium cyanide hydrolyzes readily to form hydrogen cyanide gas. The presence of acid accelerated evolution of hydrogen cyanide gas. It is reactive toward oxidizing agents. Calcium cyanide is also sometimes used to produce ammonium cyanide by reacting it with ammonium carbonate.
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