Calomel crystal structure

A lomic Atomic Crystal structure Melting point (°C) Density Thermal conduc- tivity (W/m K- ) at 20 C Electrical resistivity Specific heat Thermal expansion Magnetic susceptibility Electrode potential w.r.i. sal calomel (V) z c 2... 

Xenon difluoride XeF2 and calcium carbide (form I) CaC2 are isomorphous with Z = 2, the linear triatomic molecule occupies Wyckoff position 2(a) of site symmetry 4/mmm. Hg2Cl2 (calomel) has a very similar crystal structure, although it is tetraatomic. The molecular structure and crystal packing of XeF2 and Hg2Cl2 are compared in Fig. 9.6.15. 

The crystal structure of calomel, Hg2Cl2, which has limited solubility in water (A jp = 1.8 X 10 at 25°C). Notice the Hg-Hg bond in the structure. There is considerable evidence that a similar type of bonding occurs in aqueous solution, and so mercury(I) is represented as Hg. ... 

Figure 6-5. Electrochemical potential controlled reversible domain formation of a singlestrand repetitive 10-adenine sequence linked to a single-crystal Au(lll)-electrode surface in aqueous phosphate buffer, pH 7.6. Left Domain formation after keeping the potential at -0.61 V (vs. saturated calomel electrode, SCE) for 40 min. Recording at -0.21 V (SCE). Middle Disorder after potential stepping to -0.05 V (SCE). Right Recovery of ordered domains from the disordered surface structure shown in the middle figure, after stepping the potential back to -0.61 V (SCE) and recording at -0.21 V (SCE). Reprinted from ref. 6 with permission.

The mercury fulminate (MF) formula is HgCC N" —0 )2 with a covalent bond between the mercury and carbon atoms [20]. Its crystal density is reported to be 4.42-4.43 g cm [29, 30, 39, 40], but recent results of X-ray analysis updated it to 4,467 g cm [21]. Bulk density depends on crystal size and shape—it is reported to be between 1.35 and 1.55 g cm [38]. The heat of formation of MF is reported as being between —268 and —273 kJ moP [29, 41, 42]. The structure of the MF molecule and its crystal was published recently by Beck et al. [21]. Pure and ordinarily prepared mercury fulminate is, for all practical purposes, not hygroscopic, but its hygroscopicity rapidly increases in presence of impurities (e.g., mercury oxalate, calomel, mercuric chloride), which are generally present in the industrial... 

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