Elements, reactions with water

White Phosphorus Oxidation. Emission of green light from the oxidation of elemental white phosphoms in moist air is one of the oldest recorded examples of chemiluminescence. Although the chemiluminescence is normally observed from sotid phosphoms, the reaction actually occurs primarily just above the surface with gas-phase phosphoms vapor. The reaction mechanism is not known, but careful spectral analyses of the reaction with water and deuterium oxide vapors indicate that the primary emitting species in the visible spectmm are excited states of (PO)2 and HPO or DPO. Ultraviolet emission from excited PO is also detected (196). 

Phosphine is prepared commercially from the acid- or base-cataly2ed reaction of elemental phosphoms with water. In the acid-cataly2ed reaction, P4, white phosphoms, converts in part to red phosphoms. The latter is the main reactant (69). 

Few industrial uses have so far been found for phosphides. Ferrophosphorus is produced on a large scale as a byproduct of P4 manufacture, and its uses have been noted (p. 480). Phosphorus is also much used as an alloying element in iron and steel, and for improving the workability of Cu. Group 3 monophosphides are valuable semiconductors (p. 255) and Ca3P2 is an important ingredient in some navy sea-flares since its reaction with water releases spontaneously flammable... 

Again, we see that the alkali metals display likeness in their reactions with water. Furthermore, the reaction products always include an aqueous ion of the alkali element in which one electron has been removed, giving a 1+ ion. 

This reaction is an example of a hydrolysis reaction, a reaction with water in which new element-oxygen bonds are formed. Another example is the reaction ot PC15 (phosphorus oxidation state +5) with water to produce phosphoric acid, H3P04 (also phosphorus oxidation state - -5) ... 

The finely divided hydride produced by pyrolysis is pyrophoric in air, while synthesis from the elements produces a substantially air-stable product [1]. That prepared by reduction of butylmagnesium bromide with lithium tetrahydroalumi-nate is pyrophoric and reacts violently with water and other protic compounds [2], The hydride produced from magnesium anthracene has a very large specific surface area and is pyrophoric [3], In the context of use of the hydride for energy storage purposes, ignition and combustion behaviour of 100-400 g portions were studied, as well as the reaction with water [4],... 

The fe-ester derivatives of trithiophosphinic acids, RP(S)(SR )2, have also been studied and, similar to the metal and ammonium salts, show enhanced thermal stability compared to their parent acids. Trithiophosphonic acid Zj zA (tr im e t lr y 1 s i 1 y 1) esters have been synthesised from organo-/u.v(trim-ethylsilyl)phosphanes with elemental sulfur in toluene (Equation 40).53 These 6z,s(silyl esters) can be readily converted into the parent trithiophosphinic acid by a very slow, controlled reaction with water or methanol.53... 

Elemental composition Co 50.83%, F 49.17%. Cobalt (III) fluoride may be digested with nitric acid and the resulting acid extract diluted with water and analyzed for cobalt by various instrumental techniques (see Cobalt). The compound may be identified from its reaction with water forming a black powder material. 

Compare the properties of the trioxides of the chromium subgroup elements (their colour, thermal stability, oxidizing ability, and reaction with water). 

Hazardous Reactions with Water-Reactive Materials. Accdg to Refs 1,2,3 5, w reacts with a variety of elements, compds and mixts to generate at RT either an expln or a combustion reaction because of the hydrogen released and the heat of reaction. Table 1 presents an identification of the reactants, and a generalized classification of the results of these reactions into either expln or combustion . From Ref 3, a more quantitative approach yielded data in terms of temp increase and the time required to reach the max temp on a selected group of w-reactants (Table 2). Table 3 displays the results of an attempt to determine if the order of addition (effects of dilution and/or surface... 

Many of these have been known for a very long time, but others are difficult to generate—indeed several have only been characterized in recent years. Difficulties stem mainly from redox reactions with water or air, or through strong complexing tendencies. The problems and their solution are illustrated by such species as Mo(aq)3+, Ir(aq)3+, Ru(aq)2+, Mo2(aq)4+ and Pt(aq)2+, detailed under their respective elements elsewhere. 

Reaction with Water The most well-known and dramatic reaction of the alkali metals is with water to yield hydrogen gas and an alkali metal hydroxide, MOH. In fact, it s this reaction that gives the elements their group name The solution of metal hydroxide that results from adding an alkali metal to water is alkaline, or basic. 

With the exception of beryllium, the alkaline earth elements react with water to yield metal hydroxides, M(OH)2. Magnesium undergoes reaction only at temperatures above 100°C calcium and strontium react slowly with liquid water at room temperature. Only barium reacts vigorously. 

Halogen azides are compounds with the general formula XN3, where X is one of the halogens. These compounds are extremely reactive and can be spontaneously explosive. Their reactions with water can produce toxic fumes of the elemental halogen, acid (e.g., HC1), and NOx. The compound vapors are irritants. 

The strategy of design, illustrated in Figure 8.1, consists of an evolutionary search of the feasible design space by means of a systematic combination of thermodynamic analysis, computer simulation and only limited experiments. The approach is generic for developing a RD process, at least for similar systems. The first element of similarity is the existence of an equilibrium reaction with water as product This raises the problem of possible aqueous-phase segregation. The second element is the similarity of thermodynamics properties over a class of substrates. However, while the fatty acids and fatty esters manifest a certain... 

Oxides of elements classified in terms of their reactions with water. 

Reaction with water vapor or humid air (60-95% relative humidity) in the temperature range 20-500 °C results in the formation of a WO3 layer. No lower oxides or hydrates could be found by ESCA. The thickness of the oxide layer increases with increasing humidity. The reaction rate depends on temperature and I20]/[H2] partial pressure ratio and is more rapid than with liquid water. Water molecules are adsorbed at the tungsten surface and dissociate. The oxygen atoms difiuse into the tungsten metal, forming at first a solid solution and then the oxide compound, while, hydrogen escapes as element. 

Write the formulas and names of the hydrides of the following second-period elements Fi, C, N, O, F. Predict their reactions with water. 

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