Calcium phosphide (CP) is the

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemis ...

with the formula Ca₃P₂. It is one of several

phosphide In chemistry, a phosphide is a compound containing the ion or its equivalent. Many different phosphides are known, with widely differing structures. Most commonly encountered on the binary phosphides, i.e. those materials consisting only of phos ...

s of calcium, being described as the salt-like material composed of Ca²⁺ and P³⁻. Other, more exotic calcium phosphides have the formula CaP, CaP₃, Ca₂P₂, and Ca₅P₈. Ca₃P₂ has the appearance of red-brown crystalline powder or grey lumps. Its trade name is Photophor for the incendiary use or Polytanol for the use as

rodenticide Rodenticides are chemicals made and sold for the purpose of killing rodents. While commonly referred to as "rat poison", rodenticides are also used to kill mice, squirrels, woodchucks, chipmunks, porcupines, nutria, beavers, and voles. Despi ...

Preparation and structure

It may be formed by reaction of the elements, but it is more commonly prepared by carbothermal reduction of calcium phosphate: :Ca₃(PO₄)₂ + 8 C → Ca₃P₂ + 8 CO The structure of the room temperature form of Ca₃P₂ has not been confirmed by X-ray crystallography. A high temperature phase has been characterized by

Rietveld refinement Rietveld refinement is a technique described by Hugo Rietveld for use in the characterisation of crystalline materials. The neutron and X-ray diffraction of powder samples results in a pattern characterised by reflections (peaks in intensity) at ...

. Ca²⁺ centers are octahedral.

Uses

Metal phosphides are used as a

. A mixture of food and calcium phosphide is left where the rodents can eat it. The acid in the digestive system of the rodent reacts with the phosphide to generate the toxic gas

phosphine Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting ...

. This method of vermin control has possible use in places where rodents immune to many of the common

warfarin Warfarin, sold under the brand name Coumadin among others, is a medication that is used as an anticoagulant (blood thinner). It is commonly used to prevent blood clots such as deep vein thrombosis and pulmonary embolism, and to prevent st ...

-type (

anticoagulant Anticoagulants, commonly known as blood thinners, are chemical substances that prevent or reduce coagulation of blood, prolonging the clotting time. Some of them occur naturally in blood-eating animals such as leeches and mosquitoes, where t ...

) poisons have appeared. Other pesticides similar to calcium phosphide are

zinc phosphide Zinc phosphide ( Zn3 P2) is an inorganic chemical compound. It is a grey solid, although commercial samples are often dark or even black. It is used as a rodenticide. Zn3P2 is a II-V semiconductor with a direct band gap of 1.5 eV and may have a ...

and aluminium phosphide. Calcium phosphide is also used in

fireworks Fireworks are a class of low explosive pyrotechnic devices used for aesthetic and entertainment purposes. They are most commonly used in fireworks displays (also called a fireworks show or pyrotechnics), combining a large number of devices ...

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, ...

es, self-igniting naval pyrotechnic flares, and various water-activated ammunition. During the 1920s and 1930s,

Charles Kingsford Smith Sir Charles Edward Kingsford Smith (9 February 18978 November 1935), nicknamed Smithy, was an Australian aviation pioneer. He piloted the first transpacific flight and the first flight between Australia and New Zealand. Kingsford Smith was b ...

used separate buoyant canisters of

calcium carbide Calcium carbide, also known as calcium acetylide, is a chemical compound with the chemical formula of Ca C2. Its main use industrially is in the production of acetylene and calcium cyanamide. The pure material is colorless, while pieces of te ...

and calcium phosphide as naval flares lasting up to ten minutes. It is speculated that calcium phosphide—made by boiling bones in urine, within a closed vessel—was an ingredient of some ancient

Greek fire Greek fire was an incendiary weapon used by the Eastern Roman Empire beginning . Used to set fire to enemy ships, it consisted of a combustible compound emitted by a flame-throwing weapon. Some historians believe it could be ignited on contact w ...

formulas. Calcium phosphide is a common impurity in

, which may cause the resulting phosphine-contaminated acetylene to ignite spontaneously.

References

{{DEFAULTSORT:Calcium Phosphide Phosphides Calcium compounds Rodenticides Fumigants

Preparation and structure

Uses

See also

References