Zinc phosphide
| Zinc phosphide[1] | |
|---|---|
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| Other names trizinc diphosphide | |
| Identifiers | |
| CAS number | 1314-84-7  |
| ChemSpider | 11344765  |
| UNII | 813396S1PC |
| Jmol-3D images | {{#if:[Zn]=P[Zn]P=[Zn]|Image 1 |
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| Properties | |
| Molecular formula | Zn3P2 |
| Molar mass | 258.12 g/mol |
| Appearance | gray tetragonal crystals |
| Density | 4.55 g/cm3 |
| Melting point | 420°C |
| Boiling point | 1100°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 |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | |
| Infobox references | |
Zinc phosphide (Zn3P2) is an inorganic chemical compound.
Reactions
Zinc phosphide can be prepared by the reaction of zinc with phosphorus; however, for critical applications, additional processing to remove arsenic compounds may be needed.
- 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
Rodenticide
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, none of which have a vomiting reflex.[2]
Zinc phosphide use in New Zealand
The New Zealand Environmental Protection Authority has approved the import and manufacture of Microencapsulated Zinc Phosphide (MZP Paste) for the ground control of possums. The application was made by Pest Tech Limited, with support from Connovation Ltd, Lincoln University and the Animal Health Board. It will be used as an additional vertebrate poison in certain situations. Unlike 1080 poison, it cannot be used for aerial application.[3]
References
- ↑ Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, FL: CRC Press. pp. 4–95. ISBN 0-8493-0594-2.
- ↑ "Why rats can't vomit". Ratbehavior.org. Retrieved 2013-08-17.
- ↑ Environment Risk Management Authority New Zealand. "Zinc phosphide pest poison approved with controls". Retrieved 2011-08-14.
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
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