Zinc phosphide[1]
Other names	trizinc diphosphide
Identifiers
CAS number	1314-84-7 Y
Properties
Molecular formula	Zn3P2
Molar mass	258.12 g/mol
Appearance	gray tetragonal crystals
Density	4.55 g/cm3
Melting point	1160°C
Solubility in water	insoluble
Solubility	insoluble in ethanol, soluble in benzene, reacts with acids
Structure
Crystal structure	Tetragonal, tP40
Space group	P42/nmc, No. 137
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Zinc phosphide (Zn₃P₂) is an inorganic chemical compound.

Metal phosphides have been used as rodenticides. A mixture of food and zinc 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 phosphine gas. This method of vermin control has possible use in places where rodents immune to many of the common poisons have appeared. Other pesticides similar to zinc phosphide are aluminium phosphide and calcium phosphide.

Zinc phosphide is typically added to rodent baits in amount of around 0.75-2%. The baits have strong, pungent garlic-like odor characteristic for phosphine liberated by hydrolysis. The odor attracts rodents, but has a repulsive effect on other animals; birds, notably wild turkeys, are not sensitive to the smell. The baits have to contain sufficient amount of zinc phosphide in sufficiently attractive food in order to kill rodents in a single serving; a sublethal dose may cause aversion towards zinc-phosphide baits encountered by surviving rodents in the future.

Rodenticide-grade zinc phosphide usually comes as a black powder containing 75% of zinc phosphide and 25% of antimony potassium tartrate, an emetic to cause vomiting if the material is accidentally ingested by humans or domestic animals. However, it is still effective against rats, mice, guinea pigs and rabbits, all of which do not have a vomiting reflex. [1]

[edit] Reactions

Zinc phosphide can be prepared by the reaction of zinc with phosphorus:

3Zn + 2P → Zn₃P₂

Zinc phosphide will react with water to produce phosphine (PH₃) and zinc hydroxide (Zn(OH)₂):

Zn₃P₂ + 6H₂O → 2PH₃ + 3Zn(OH)₂

[edit] References

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (May 2009)

[edit] External links

• Zinc Phosphide Pesticide Information Profile - Extension Toxicology Network
• EPA Proposed Risk Mitigation Decision for Nine Rodenticides
• Zinc phosphide properties and use in Michigan
• MD0173 - Pesticides in the military

v • d • e   Zinc compounds ZnBr2 · Zn(CN)2 · ZnCl2 · Zn(ClO3)2 · ZnCrO4 · ZnF2 · ZnH2 · ZnI2 · ZnMoO4 · Zn(NO3)2 · ZnO · ZnO2 · Zn(OH)2 · ZnS · ZnSO4 · ZnSb · ZnSe · ZnTe · Zn2P2O7 · Zn3As2 · Zn3N2 · Zn3P2 · Zn3(PO4)2

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