Phosphine is a colorless, flammable gas with the chemical formula PH₃, consisting of one phosphorus atom bonded to three hydrogen atoms in a pyramidal structure. First prepared in 1783 by French chemist Philippe Gengembre by heating phosphorus with an alkali solution, this highly toxic compound is notorious for its revolting smell of rotting fish or garlic at low concentrations. Despite being one of the most dangerous industrial gases – capable of spontaneous ignition and causing rapid organ failure – phosphine plays crucial roles in semiconductor manufacturing for doping silicon chips and as a fumigant for stored grain. Recently thrust into the spotlight by its controversial detection in Venus’s atmosphere, where it might indicate biological processes, phosphine represents both a deadly hazard in earthly applications and a potential biosignature in the search for extraterrestrial life.

Find a review of the 50 most important industrial gases here.

20 Fun Facts About Phosphine

Beyond the basics above, what else should we know about Phosphine? Check out the 20 fun facts below!

1. Phosphine can spontaneously ignite at room temperature when contaminated with traces of diphosphine (P₂H₄), creating “will-o’-the-wisp” lights in marshes.
2. The 2020 Venus phosphine detection suggested 20 parts per billion in clouds where it should be destroyed in minutes, sparking alien life debates.
3. The molecule’s pyramid shape has a 93.5° H-P-H bond angle, making it more pointed than ammonia’s 107° angle.
4. Phosphine is 1.2 times heavier than air but disperses quickly due to its low boiling point of -87.7°C.
5. Grain fumigation with phosphine takes 5-10 days because the gas must penetrate deep into grain kernels to kill pest eggs.
6. The compound glows green when burning, producing phosphoric acid smoke that forms eerie shapes in still air.
7. Semiconductor fabs use 99.9999% pure phosphine to create n-type silicon by adding phosphorus atoms to crystal lattices.
8. Phosphine forms naturally in sewers when phosphate detergents meet anaerobic bacteria, creating explosion hazards.
9. The gas kills by disrupting cytochrome c oxidase worse than cyanide, causing cells to suffocate despite adequate oxygen.
10. Fish actually produce trace phosphine in their guts, contributing to the characteristic “fishy” smell of degrading seafood.
11. Acetylene contaminated with phosphine was responsible for many early lighthouse explosions before the connection was understood.
12. The molecule rotates 10¹¹ times per second, creating microwave emissions detectable by radio telescopes at 267 GHz.
13. Phosphine detectors use silver nitrate strips that turn black from Ag₃P formation at just 0.3 ppm exposure.
14. Meteorites contain phosphine precursors, suggesting the molecule might seed life’s phosphorus chemistry on young planets.
15. The compound costs $5,000 per kilogram at semiconductor purity, requiring specialized tantalum-lined cylinders for storage.
16. Cave formations trap ancient phosphine from bat guano decomposition, creating pockets of toxic gas for spelunkers.
17. Military smokescreens accidentally produced phosphine when white phosphorus munitions hit wet ground, causing additional casualties.
18. The gas liquefies under just 20 atmospheres at room temperature, unlike ammonia which requires 145 atmospheres.
19. Phosphine-resistant insects are evolving rapidly, with some grain beetles now surviving concentrations 100 times historical lethal doses.
20. Jupiter and Saturn contain thousands of ppm of phosphine in their atmospheres, created by extreme pressure and temperature conditions.

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