Sulfuric acid Crystal structure

Atomic weight 186.22. Gray metal powder the solid has a platinum-like luster. M.p. 3170°C d 20.35 Brinell hardness 250. Readily soluble in nitric acid and slowly in sulfuric acid. Crystal structure A 3 type. 

Analysis of the volumetric effects indicates that as a result of such mechanical activation, iron and manganese are concentrated in the extended part of the crystal, while tantalum and niobium are predominantly collected in the compressed part of the distorted crystal structure. It is interesting to note that this effect is more pronounced in the case of tantalite than it is for columbite, due to the higher rigidity of the former. Akimov and Chernyak [452] concluded that the effect of redistribution of the ions might cause the selective predominant dissolution of iron and manganese during the interaction with sulfuric acid and other acids. 

Given the efforts in this group and others (Table 1) to form the Cd based II-VI compounds, studies of the formation of Cd atomic layers are of great interest. The most detailed structural studies of Cd UPD have, thus far, been published by Gewirth et al. [270-272]. They have obtained in-situ STM images of uniaxial structures formed during the UPD of Cd on Au(lll), from 0.1 M sulfuric acid solutions. They have also performed extensive chronocoulometric and quartz crystal microbalance (QCM) studies of Cd UPD from sulfate. They have concluded that the structures observed with STM were the result of interactions between deposited Cd and the sulfate electrolyte. However, they do not rule out a contribution from surface reconstructions in accounting for the observed structures. 

Single crystals of peroxomonosulfuric acid, H2S05 (also known as Caro s acid) have been prepared by the reaction of fuming sulfuric acid and H202. In the crystal structure, the molecules are connected via hydrogen bonds.49 The distance within the peroxo group of the anion is 1.46 A. 

Besides the oxide sulfate described above, (NH4)2[Pt2(S04)4(H20)2] is obtained in the reaction of Pt(N03)2 with concentrated sulfuric acid in sealed glass ampoules at 400 °C.124 In the crystal structure, Pt2 dumbbells are coordinated by four bidentate-bridging sulfate ions and two axial H20 molecules. The... 

As an example we consider the Au(100) surface of a single crystal Au electrode [3]. This is one of the few surfaces that reconstruct in the vacuum. The perfect surface with its quadratic structure is not thermodynamically stable it rearranges to form a denser lattice with a hexagonal structure (see Fig. 15.3), which has a lower surface energy. In an aqueous solution the surface structure depends on the electrode potential. In sulfuric acid the reconstructed surface is observed at potentials below about 0.36 V vs. SCE, while at higher potentials the reconstruction disappears, and the perfect quadratic structure is ob-... 

Working first with Polanyi, Weissenberg, and Brill, and later as the leader of the Textile Chemistry Section, Mark successively published papers on the crystal structures of hexamethylenetetramine, pentaerythritol, zinc salts, tin, urea, tin salts, triphenylmethane, bismuth, graphite, sulfur, oxalic acid, acetaldehyde, ammonia, ethane, diborane, carbon dioxide, and some aluminum silicates. Each paper showed his and the laboratory s increasing sophistication in the technique of X-ray diffraction. Their work over the period broadened to include contributions to the theories of atomic and molecular structure and X-ray scattering theory. A number of his papers were particularly notable including his work with Polanyi on the structure of white tin ( 3, 4 ), E. Wigner on the structure of rhombic sulfur (5), and E. Pohland on the low temperature crystal structure of ammonia and carbon dioxide (6, 7). The Mark-Szilard effect, a classical component of X-ray physics, was a result of his collaboration with Leo Szilard (8). And his work with E. A. Hauser (9, 10, 11) on rubber and J. R. 

Molecular sieves are crystalline metal aluminosilicates (1). Openings in their crystal structure permit passage of many gas constituents while preferentially adsorbing large, polar, or unsaturated compounds. Acid gas compounds may be adsorbed by certain types of molecular sieves. When used for H2S removal, the sieve is regenerated by a thermal swing cycle CL), being heated to release the H2S for downstream sulfur recovery. 

Fig. 23. Significant coarsening of the domain structure did not occur, at least for the time scale investigated. Thus, charge-induced reconstruction in sulfuric acid results in a much smaller domain size than that associated with a freshly flame-annealed crystal. The domain boundaries act as preferred nucleation sites for subsequent (hex) (1 X 1) transformation, which occurs much more rapidly than for a freshly flame-annealed sample. Studies of this nature have provided keen insight into aging effects that would be difficult to assess by other means.

Many properties of polyamides are attributable to the formation of hydrogen bonds between the NH and CO groups of neighboring macromolecules. This is evidenced by their solubility in special solvents (sulfuric acid, formic acid, m-cresol), their high melting points (even when made from aliphatic components), and their resistance to hydrolysis. In addition, polyamides with a regular chain structure crystallize very readily. 

Amorphous forms exhibit two colors, occurring as a red powder of density 4.26g/cm3 that has a hexagonal crystal structure and a black vitreous solid of density 4.28g/cm3. The red amorphous selenium converts to the black form on standing. Amorphous selenium melts at 60 to 80°C insoluble in water reacts with water at 50°C when freshly precipitated soluble in sulfuric acid, benzene and carbon disulfide. 

Crystalline selenium exhibits two monochnic forms an alpha form constituting dark red transparent crystals, density 4.50 g/cm. The alpha form converts to a metastable beta form of hexagonal crystal structure when heated to about 170°C. Both the crystalline forms are insoluble in water soluble in sulfuric and nitric acids very slightly soluble in carbon disulfide. Also, both the crystalline forms convert into gray metallic modification on heating. 

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