Energy mercury compounds

Table t.1-181 Spin-orbit splitting energies 4so of mercury compounds... 

Oxidation numbers for Hg (I) and (II), as in Hg20, mercurous oxide, HgO, mercuric oxide, and Hg 0 2 [mercuiy(ll) peroxide]. The mercurous ion is dimercury(2+) or dimercury(I), Hg2. Relativity greatly strengthens the Hg-Hg bond but may also explain the metal s liquidity. Relativity shrinks and stabilizes mercury s 6s orbital, making Hg rather like a noble gas but favoring linear sp hybrids with more (1/2 s) low-energy s nature than the tetrahedral sp (1/4 s). The many (linear) oigano-mercury compounds are excluded here. 

Table 14.2 shows that all three elements have remarkably low melting points and boiling points—an indication of the weak metallic bonding, especially notable in mercury. The low heat of atomisation of the latter element compensates to some extent its higher ionisation energies, so that, in practice, all the elements of this group can form cations in aqueous solution or in hydrated salts anhydrous mercuryfll) compounds are generally covalent. 

Details have been collected for the determination of some 50 elements by this technique21,22 and it is possible to effect many difficult separations, such as Cu and Bi, Cd and Zn, Ni and Co it has been widely used in the nuclear energy industry. A number of organic compounds can also be determined by this procedure, e.g. trichloroacetic acid and 2,4,6-trinitrophenol are reduced at a mercury cathode in accordance with the equations... 

International Atomic Energy Agency (1972). Mercury Contamination in Man and His Environment, Technical Report Series 137—Contains some useful accounts of work done in Sweden on ecotoxicology of organomercury compounds that is difficult to find in the general literature. 

Fig. 5.6 (Left) Comparison of band energy levels for different II-VI compounds. Note the high-energy levels of ZnSe. Representation is made here for electrodes in contact with 1 M HQO4. The reference is a saturated mercury-mercurous sulfate electrode, denoted as esm (0 V/esm = +0.65 V vs. SHE). (Right) Anodic and cathodic decomposition reactions for ZnSe at their respective potentials (fidp, Fdn) and water redox levels in the electrolytic medium of pH 0. (Adapted from [121])...

In addition to the ability to react nonspecifically with hydrocarbons, active nitrogen can readily participate in energy transfer reactions with volatile organometal-lic compounds, leading to atomic emission from the metal atom. By use of appropriate optical filters, selective detection of elements such as aluminum, lead, tin, and mercury has been achieved in the presence of large excesses of organics [58],... 

Electrophilic substitution at the anthraquinone ring system is difficult due to deactivation (electron withdrawal) by the carbonyl groups. Although the 1-position in anthraquinone is rather more susceptible to electrophilic attack than is the 2-position, as indicated by jt-electron localisation energies [4], direct sulphonation with oleum produces the 2-sulphonic acid (6.3). The severity of the reaction conditions ensures that the thermodynamically favoured 2-isomer, which is not subject to steric hindrance from an adjacent carbonyl group, is formed. However, the more synthetically useful 1-isomer (6.7) can be obtained by sulphonation of anthraquinone in the presence of a mercury(II) salt (Scheme 6.4). It appears that mercuration first takes place at the 1-position followed by displacement. Some disulphonation occurs, leading to the formation of the 2,6- and 2,7- or the 1,5- and 1,8-disulphonic acids, respectively. Separation of the various compounds can be achieved without too much difficulty. Sulphonation of anthraquinone derivatives is also of some importance. 

The Arrhenius parameters and the thermochemical sum of the phenyl-carbon and phenyl-halogen bond dissociation energies are shown in Table 8. The extent of the diphenyl mercury decomposition was determined from the weight of mercury produced. It is the present author s opinion that in calculating the Arrhenius parameters for this compound Carter et al.81 gave too great a statistical... 

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