Chemical reactivity of solids

Faraday Society, Discussion No. 28 (1959b) Crystal Imperfections and the Chemical Reactivity of Solids (Aberdeen University Press). 

Enhanced chemical reactivity of solid surfaces are associated with these processes. The cavitational erosion generates unpassivated, highly reactive surfaces it causes short-lived high temperatures and pressures at the surface it produces surface defects and deformations it forms fines and increases the surface area of friable solid supports and it ejects material in... 

It is now well established that surface defects and imperfections determine the chemical reactivity of solid surfaces, making defect engineering an important branch of modern solid state chemistry and physics. However, this reactivity can in turn be responsible for the toxicity of different silicate dusts. A number of interesting studies have appeared which correlate the surface properties of different silicates to their genotoxicity and potential health hazards.190 192 In particular the potential of a surface to generate and release free radicals via the... 

Physical Factors Influencing the Chemical Reactivity of Solid Materials—A Prelimirtary Investigation , NAD-CR-RDTR-137, Naval Ammo Depot, Crane (1969) 192) L. Avrami W.E,... 

The bulk properties of macroscopic crystals cannot be affected drastically by the difference which exists between the structure of the interior and that of a surface film which is approximately 10,000 atoms deep. However, even for macroscopic crystals, rate phenomena such as modification changes which are initiated within the surface are likely to be influenced by the environment, which would include molecules which are conventionally described as physically adsorbed. Apparently it is not generally understood that even the presence of a noble gas can affect the chemical reactivity of solids. Brunauer (3) explained that in principle physical adsorption of molecules should affect the solid in the same manner as chemisorption. As action and reaction are equal, chemisorption may have a stronger effect on both the solid and the adsorbed molecule. 

Chemical Reactivity of Solids. The description of the surface film of a solid as containing its ions in a lower than normal coordination and having internuclear distances smaller than those of the bulk of the crystal does not in itself supply the key to a better understanding of surface chemistry. One has to find the relation-... 

Discussion of the Faraday Society on "Crystal Imperfections and the Chemical Reactivity of Solids" held at Queen s University, Kingston, Ontario, Canada, to be published see also Discussions Faraday Soc., 5, (1949). 

Sherwood, J. N. and Gallagher, H. G. (1984). The influence of lattice imperfections on the chemical reactivity of solids. Final Technical Report European Research Office of the U. S. Army, Contract Number DAIA-37-81-M-0395. Avail. NTVS Gov. Rep. Announce. Index (NS) 1984, 84, 83. [287]... 

Unintentional and perhaps unrecognized incorporation of impurities may occur during crystal preparation. The addition of a controlled quantity of a selected additive is termed doping, and specific systems of this type are discussed in later chapters. Many studies of the influences of additives on decompositions have been reported. Fewer investigations have been concerned with the influences of compositional variations over extensive ranges on the chemical reactivities of solid solutions. 

The interactions of the chemical kinetic and macroscopic transport processes depend to a variable extent on each of the nine couples given in Table 1. For example, transport of solutes by water runoff is a result of atmospheric precipitation, land exposure to water, chemical reactivity of solids in an aqueous solution, and flow of water over the continental surface. The net result of this process is controlled by coupling among the physical, hydrological and chemical entities in Table 1, as shown below ... 

Influence the Reactivity of Solids, with Special Emphasis on the Control of the Chemical Processes in Relation to Practical Applications by V.V. Boldyrev, M. Bulens and B. Delmon... 

Many authoritative accounts of both general and specific aspects of the reactions of solids and related topics appear as plenary lectures and research papers in the series of International Symposia on the Reactivity of Solids [82—86]. The material presented at these meetings reflects contemporary interests in a diverse and developing field, so that changes in emphasis are to be discerned in the content of the successive symposia held at four-yearly intervals. Reference can also be made here to the conference on Reaction Kinetics in Heterogeneous Chemical Systems in which useful review material is found [87],... 

Point defects were mentioned in a prior chapter. We now need to determine how they aiffect the structure auid chemical reactivity of the solid state. We will begin by identifying the various defects which can arise in solids and later will show how they can be manipulated to obtain desirable properties not found in naturally formed solids. Since we have already defined solids as either homogeneous and heterogeneous, let us look first at the homogeneous t5 e of solid. We will first restrict our discussion to solids which are stoichiometric, and later will examine solids which can be classified as "non-stoichiometric", or having an excess of one or another of one of the building blocks of the solid. These occur in semi-conductors as well as other types of electronically or optically active solids. 

It is for this reason that compounds containing impurities sometimes have quite different chemical reactivities than the purest ones. That also has an effect upon the chemical reactivity of the solid. However, the interstitial impurity does not affect the lattice ordering at all. Now, let us look at another type of defect in the solid. Let us consider the heterogeneous lattice... 

R. J. Madix, Selected principles in surface reactivity reaction kinetics on extended surfaces and the effects of reaction modifiers on surface reactivity, in The Chemical Physics of Solid Surfaces and Heterogeneous Catalysis, Vol. 4, ed. D. A. King and D. P. Woodruff, Elsevier, Amsterdam, 1982, 1. 

Frequently the most important planar defects in a crystal are the external surfaces. These may dominate chemical reactivity, and solids designed as catalysts or, for example, as filters must have large surface areas in order to function. Rates of reaction during corrosion are frequently determined by the amount of surface exposed to the corrosive agent. (A further discussion of surface physics and chemistry, although fascinating, is not possible within the scope of this volume.)... 

There are a number of other reasons for carrying out size reduction. It may, for example, be necessary to break a material into very small particles in order to separate two constituents, especially where one is dispersed in small isolated pockets. In addition, the properties of a material may be considerably influenced by the particle size and, for example, the chemical reactivity of fine particles is greater than that of coarse particles, and the colour and covering power of a pigment is considerably affected by the size of the particles. In addition, far more intimate mixing of solids can be achieved if the particle size is small. 

Feltz, A. Martin, A. (1987) Solid-state reactivity and mechanisms in oxide systems. 11 Inhibition of zinc ferrite formation in zinc oxide - a-iron(lll) oxide mixtures with a large excess of a-iron(lll) oxide. In Schwab, G.M. (ed.) Reactivity of solids. Elsevier, 2 307—313 Fendorf, S. Fendorf, M. (1996) Sorption mechanisms of lanthanum on oxide minerals. Clays Clay Miner. 44 220-227 Fendorf, S.E. Sparks, D.L. (1996) X-ray absorption fine structure spectroscopy. In Methods of Soil Analysis. Part 3 Chemical Methods. Soil Sd. Soc. Am., 377-416 Fendorf, S.E. Eick, M.J. Grossl, P. Sparks, D.L. (1997) Arsenate and chromate retention mechanisms on goethite. 1. Surface structure. Environ. Sci. Techn. 31 315-320 Fendorf, S.E. Li,V. Gunter, M.E. (1996) Micromorphologies and stabilities of chromiu-m(III) surface precipitates elucidated by scanning force microscopy. Soil Sci. Soc. Am. J. 60 99-106... 

Ideally, the variation of reaction rate with temperature for gas-carbon reactions can be divided into three main zones, as shown in Fig. 5 and as previously discussed by Wicke (31) and Rossberg and Wicke (82). In the low-temperature zone. Zone I, the reaction rate is controlled solely by the chemical reactivity of the solid (step 3). The measured or apparent activa-... 

Boukherroub, R. Chemical reactivity of hydrogen-terminated crystalline silicon surfaces. Current Opinion in Solid State Materials Science 9, 66 (2005). 

Recently Freeman, Anderson and Campisi [11] examined the effects of X-rays on the chemical reactivity of ammonium perchlorate in the solid state. They found that pre-exposure of ammonium perchlorate to high energy radiation greatly affects the way it decomposes thermally. 

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