Non-metals phosphorus

Introduction Sublimation of white and red phosphorus has been examined in numerous studies summarized in [1]. Of particular interest is the enormous difference between the evaporation rates of white and red phosphorus, reaching 

6-7 orders of magnitude according to the existing estimates [2-4]. The low-vapour pressure of red phosphorus was attributed, in all these studies, to complicated removal of phosphorus in the form of the most stable tetrahedral P4 molecules from the surface of triclinic red phosphorus containing no such fragments in the crystal structure. In 1997, L vov and Novichikhin [5] compared the experimental (measured by the second-law method) and calculated enthalpies of vaporization and concluded that vaporization of red phosphorus occurs with the formation of P2 rather than P4 molecules (see Sect. 10.3). 

Results and Discussion This conclusion is also confirmed by the data given below, obtained by the third-law method. The thermod3mamic functions required to determine the enthalpy are given in Table 16.1. Only one paper published by Melville and Gray [2] 70 years ago was found, in which the equivalent pressure of red phosphorus was measured under the free-surface vaporization conditions (after Langmuir). The vapour pressure in this study was determined in the range 578-673 K from the mass of the vapour condensate (Table 16.2). 

The quantities determined from these data by the third-law method 

Comparison of the data given in Table 16.2 shows that the difference between the experimental and calculated values at various temperatures reaches 10-20%. Nevertheless, this agreement can be considered as satisfactory, taking into account the poor reproducibility of the initial data [2]. 

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Lead chromate Sulfur Lead(II) chlorite Non-metals Phosphorus(III) oxide Potassium bromate Non-metals Potassium chlorate Charcoal, etc., or Non-metals Potassium chlorite Sulfur Potassium perchlorate Sulfur Potassium permanganate Non-metals Silver bromate Sulfur compounds Silver chlorite Hydrochloric acid, etc. 

Other non-metals phosphorus, sodium, nitrogen and deuterium... 

Cheng L, Zhang Z, Niu W, Xu G, Zhu L (2008) Carbon-supported Pd nanocatalyst modified by non-metal phosphorus for the oxygen reduction reaction. J Power Sources 182(l) 91-94... 

Majority mineral elements Or quantity elements, formerly referred to as macroelements, which occur in food in larger amounts, usually in hundredths to units of weight per cent (hundreds to ten thousands mg/kg) and include alkali metals sodium (Na) and potassium (K), alkaline earth metals magnesium (Mg) and calcium (Ca), halogen chlorine (Cl) and non-metals phosphorus (P) and sulfur (S). 

Among the non-metals, nitrogen and chlorine, for example, are gases, but phosphorus, which resembles nitrogen chemically, is a solid, as is iodine which chemically resembles chlorine. Clearly we have to consider the physical and chemical properties of the elements and their compounds if we are to establish a meaningful classification. 

Nitrogen is unusual in forming so many oxides. The acidity of the Group V oxides falls from phosphorus, whose oxides are acidic, through arsenic and antimony whose oxides are amphoteric, to the basic oxide ofbismuth. This change is in accordance with the change from the non-metallic element, phosphorus, to the essentially metallic element, bismuth. The +5 oxides are found, in each case, to be more acidic than the corresponding + 3 oxides. 

Sulphur is less reactive than oxygen but still quite a reactive element and when heated it combines directly with the non-metallic elements, oxygen, hydrogen, the halogens (except iodine), carbon and phosphorus, and also with many metals to give sulphides. Selenium and tellurium are less reactive than sulphur but when heated combine directly with many metals and non-metals. 

Chlorine reacts with most elements, both metals and non-metals except carbon, oxygen and nitrogen, forming chlorides. Sometimes the reaction is catalysed by a trace of water (such as in the case of copper and zinc). If the element attacked exhibits several oxidation states, chlorine, like fluorine, forms compounds of high oxidation state, for example iron forms iron(III) chloride and tin forms tin(IV) chloride. Phosphorus, however, forms first the trichloride, PCI3, and (if excess chlorine is present) the pentachloride PCI5. 

Arsenic exists as grey, yellow and black forms of differing physical properties and susceptibilities towards atmospheric oxygen. The general chemistry is similar to that of phosphorus but whereas phosphorus is non-metallic, the common form of arsenic is metallic. Traces of arsenides may be present in metallic residues and drosses these may yield highly toxic arsine, ASH3, with water. 

Industrially, chlorine is obtained as a by-product in the electrolytic conversion of salt to sodium hydroxide. Hazardous reactions have occuned between chlorine and a variety of chemicals including acetylene, alcohols, aluminium, ammonia, benzene, carbon disulphide, diethyl ether, diethyl zinc, fluorine, hydrocarbons, hydrogen, ferric chloride, metal hydrides, non-metals such as boron and phosphorus, rubber, and steel. 

Phosphorus also occurs in all living things and the phosphate cycle, including the massive use of phosphatic fertilizers, is of great current interest.O 20) -pj.jg movement of phosphorus through the environment differs from that of the other non-metals essential to life (H, C, N, O and S) because it has no volatile compounds that can circulate via the atmosphere. Instead, it circulates via two rapid biological... 

There are three main types of pyrophoric agents white phosphorus and other inorganic non metals, finely divided metals, and certain organometallic compds... 

See Chromyl chloride Non-metal halides Oxygen (Gas) Phosphorus tribromide Ruthenium(VIII) oxide Phosphorus tribromide... 

See Chromium pentafluoride Phosphorus trichloride Chromyl chloride Non-metal halides Fluorine Phosphorus halides Iodine chloride Phosphorus trichloride... 

Alone, or Non-metals, or Sulfuric acid Goralevich, D. K., J. Russ. Phys. Chem. Soc., 1926, 58, 1115 It explodes on heating or impact, or in contact with charcoal, phosphorus, sulfur or sulfuric acid. 

Although the massive metal is relatively inert, when powdered it becomes very reactive. The dry powder may react explosively at elevated temperatures with nitrogen, phosphorus, oxygen, sulfur and other non-metals. The halogens react similarly, and in contact with hot cone, nitric acid and other oxidants it may explode (often after a delay with nitric acid). The powder is pyrophoric and readily ignitable by friction, heat or static sparks, and if dry bums fiercely. Presence of... 

See Phosphorus tribromide Sulfur acids Phosphorus trichloride Sulfur acids See Other IODINE COMPOUNDS, HALOPHOSPHINES, NON-METAL HALIDES... 

See Phosphorus Non-metal oxides See other non-metal oxides, oxidants... 

See metal halogenates non-metals See also metal chlorates phosphorus, etc. 

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