Formal Oxidation States For Pyrite, Marcasite, and Arsenopyrite
From the perspective of classical inorganic chemistry, which assigns formal oxidation states to each atom, pyrite is probably best described as Fe2+S22ā. This formalism recognizes that the sulfur atoms in pyrite occur in pairs with clear SāS bonds. These persulfide units can be viewed as derived from hydrogen disulfide, H2S2. Thus pyrite would be more descriptively called iron persulfide, not iron disulfide. In contrast, molybdenite, MoS2, features isolated sulfide (S2ā) centers because the oxidation state of molybdenum is Mo4+. The mineral arsenopyrite has the formula FeAsS. Whereas pyrite has S2 subunits, arsenopyrite has AsS units, formally derived from deprotonation of H2AsSH. Analysis of classical oxidation states would recommend the description of arsenopyrite as Fe3+(AsS)3ā.
Read more about this topic: Pyrite
Famous quotes containing the words formal and/or states:
“It is in the nature of allegory, as opposed to symbolism, to beg the question of absolute reality. The allegorist avails himself of a formal correspondence between “ideas” and “things,” both of which he assumes as given; he need not inquire whether either sphere is “real” or whether, in the final analysis, reality consists in their interaction.”
—Charles, Jr. Feidelson, U.S. educator, critic. Symbolism and American Literature, ch. 1, University of Chicago Press (1953)
“Colonel “Bat” Guano: Okay, I’m going to get your money for you. But if you don’t get the President of the United States on that phone, you know what’s going to happen to you?
Group Captain Lionel Mandrake: What?
Colonel “Bat” Guano: You’re going to have to answer to the Coca-Cola company.”
—Stanley Kubrick (b. 1928)