Divalent metal carbonate

Olley JM, Roberts RG, Murray AS (1997) A novel method for determining residence times of river and lake sediments based on disequilibriiun in the thorium decay series. Water Resom Res 33 1319-1326 Onac BP, Lauritzen S-E (1996) The climate of the last 150,000 years recorded in speleothems preliminary results from north-western Romania. Theor Appl Karstology 9 9-21 O Neil JR., Clayton RN, Mayeda TK (1969) Oxygen isotope fractionation in divalent metal carbonates. J ChemPhys 51 5547-5558... 

O Neil JR, Clayton RN, Mayeda TK (1969) Oxygen isotope fractionation in divalent metal carbonates. J Chem Phys 51 5547-5558... 

Figure 6. Stability constants of some hi divalent metal carbonate complexes plotted against stability constants for the corresponding oxalate complexes. Data are from literature and are for 1 = 0. The equation of the line is log Kassoc (MCOs ) = 1.11 X log Kassoc (MC OA)-...

Although the Ca-Mg carbonates constitute the most frequently encountered carbonate minerals, other metal carbonates can also be important. Of these, the most abundant are siderite (FeCO ) and rhodocrosite (MnC03). The divalent metal carbonates typically occur as. solid. solutions and so contain trace to major amounts of one or more secondary metal cations (cf. Reeder 1983). Solubilities of some binary metal-carbonate solid solutions are known (cf. Glynn 1990). 

Pokrovsky, O.S. and Schott, J., Surface chemistry and dissolution kinetics of divalent metal carbonates, Environ. Sci. Technol., 36, 426, 2002. 

Ethylene—Dicarboxylic Acid Copolymers. Partial neutralization of copolymers containing carboxyls in pairs on adjacent carbons, eg, ethylene—maleic acid, has been described (11). Surprisingly, there is no increase in stiffness related to neutralization. Salts with divalent metal cations are not melt processible. The close spacing of the paired carboxyl groups has resulted in ionic cluster morphology which is distinct from that of the commercial ionomer family. 

AT-heterocyclic carbenes show a pure donor nature. Comparing them to other monodentate ligands such as phosphines and amines on several metal-carbonyl complexes showed the significantly increased donor capacity relative to phosphines, even to trialkylphosphines, while the 7r-acceptor capability of the NHCs is in the order of those of nitriles and pyridine [29]. This was used to synthesize the metathesis catalysts discussed in the next section. Experimental evidence comes from the fact that it has been shown for several metals that an exchange of phosphines versus NHCs proceeds rapidly and without the need of an excess quantity of the NHC. X-ray structures of the NHC complexes show exceptionally long metal-carbon bonds indicating a different type of bond compared to the Schrock-type carbene double bond. As a result, the reactivity of these NHC complexes is also unique. They are relatively resistant towards an attack by nucleophiles and electrophiles at the divalent carbon atom. 

Trace elements can be adsorbed on the surface of calcite, influencing their solubility in calcareous soils of arid and semi-arid zones. The carbonate bound fraction is the major solid-phase component for many trace elements (Cd, Pb, Zn, Ni and Cu) in arid and semi-arid soils, especially in newly contaminated soils (Table 5.3). In Israeli arid soils treated with metal nitrates, the carbonate bound fraction is the largest solid-phase component (60-80%, 50-60%, 40-60%, 30-40%, and 25-36% for Cd, Pb, Zn, Ni, and Cu respectively). Divalent metallic cations at low aqueous concentrations first associate with calcite via adsorption reactions. Then they may be incorporated into the calcite lattice as a co-precipitate by recrystallization (Franklin and Morse, 1983 Komicker et al., 1985 Davis et al., 1987 Zachara et al., 1988 Reeder and Prosky, 1986 Pingitore and... 

Carbene" and Metal-2" functional groups consist of a generic divalent metal joined to a carbon atom by a double bond. 

If solid samples are insoluble in water, some decomposition procedure must be used. For inorganic materials, decomposition with mineral acids is most often employed (for a survey of decomposition techniques see [33]). When the sample cannot be dissolved in an acid, it can either be fused (most often with alkali carbonates, hydroxides or their mixtures [157, 47]) or sintered (usually with mixtures of alkali carbonates with divalent metal oxides, sometimes in the presence of oxidants [54]). Sintering is usually preferable, because then contamination of the sample and the resultant ionic strength are lower than is the... 

Ferrite. Iron which, in pig iron or steel, has not combined with carbon to form cementite (FeaC). It exists in a, /9, y and 8 forms, which vary in magnetism and ahility to dissolve cementite. Name also applied to compd NaFe02 (called Na ferrite), to ferromagnetic oxides having a definite cryst structure (spinels) and the formula M++Fe ++04 of which the divalent metal may be Fe, Ni, Zn, or Mn. The magnetic props vary accdg to the divalent atom present, and ferrites are now tailored for their desired effect, as Ni-Al ferrite ... 

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