Re: Travellers beware, by Robert Clark, Your Views, St. Albert Gazette, March 19.
Mr. Clark’s letter contains serious chemistry errors. First, mustard gas is not the same as phosgene. Both of these compounds have been used as chemical weapons, but they are completely differently.
Mustard gas is a sulfur-containing compound with the chemical formula C4H8Cl2S. Phosgene has the formula COCl2. Mr. Clark misidentified phosgene as PH3, a compound which is actually named phosphine. Many students of chemistry have also mistakenly thought that phosgene contains phosphorus (P). Indeed, chemical nomenclature can be confusing at times!
Mr. Clark stated that “phosgene-generating capsules are being used extensively in the Far East to combat bed bugs in hotels.” This is incorrect, and I suspect the mistake arose from confusing phosgene with phosphine.
Aluminum phosphide (AlP) pellets can be used to control pests. When aluminum phosphide is ingested by a rodent, for example, the compound reacts to form phosphine (PH3), which is toxic and kills the animal. The small amount of phosphine produced inside the animal would not pose any threat to humans.
Mr. Clark’s notion that phosgene (COCl2) is used to fumigate hotel rooms is simply wrong. Battlefield chemical weapons are not used as insecticides!
Mr. Clark has wartime experience preparing for the horrors of chemical warfare. I suggest that his memories of that experience might be enriched by reading up on the properties of, and the differences among, chemical weapons of that era. In the subject of chemistry, Wikipedia is a very reliable, free resource.
Lawton Shaw, Ph.D., associate professor of chemistry, Athabasca University
