Inorganics, solubility definition

This volume covers ongoing research and, thus, leaves many questions unanswered and many problems unsolved. The geochemistry of disposed radioactive wastes involves many complex issues that will require years of additional research to resolve. High-priority problems include integration of geochemical data with computer models of chemical interaction and transport, definition of environmental conditions that affect the behavior of radionuclides at specific disposal sites, evaluation of complex formation of dissolved radionuclides with inorganic and organic complexants, and determination of radionuclide solubilities in natural waters. 

SOLUBILITY OF PRECIPITATES A large number of reactions employed in qualitative inorganic analysis involve the formation of precipitates. A precipitate is a substance which separates as a solid phase out of the solution. The precipitate may be crystalline or colloidal, and can be removed from the solution by filtration or by centrifuging. A precipitate is formed if the solution becomes oversaturated with the particular substance. The solubility (5) of a precipitate is by definition equal to the molar concentration of the saturated solution. Solubility depends on various circumstances, like temperature, pressure, concentration of other materials in the solution, and on the composition of the solvent. 

The broadest definition of, for example, total mercury (Hg) in a sample is the sum of the elemental Hg°, the Hg in all inorganic compounds of Hg +, the Hg in all inorganic compounds of Hg +, and the Hg in all organic compounds in which Hg is bonded to C, O, N, S, or some other element. All phases are included because some species may be present in the vapor phase (Hg°), some soluble in water, and some insoluble in water or present in the particulate phase of an air sample. More limited definitions of total are often used in analytical methods that separate physical phases or chemical forms that contain the element of interest. 

Many insoluble compounds of the metals are found in the earth s crust. Solids that contain these compounds are the ores from which metals are extracted. Ores contain minerals, which are naturally occurring inorganic solid substances having definite chemical compositions and characteristic crystalline structures. These minerals occur in mixtures with relatively large amounts of gangue—sand, soil, rock, and other material. Soluble compounds are found dissolved in the sea or in salt beds in areas where large bodies of water have evaporated. Metal ores can be classified by the anions with which the metal ions are combined (Table 26-1 and Figure 26-1). 

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