Stoichiometric compounds, calculating densities/concentrations

Calculating Densities/Concentrations in Stoichiometric Compounds or Dilute Solutions... 

When calculating the mass density, molar concentration, or molar volume of a specific individual species that is present in combination with other species (e.g., in a compound or solution), further work is needed. If the material s composition can be expressed in terms of a single stoichiometric compound or formula unit, the approach is still fairly straightforward— it just requires application of the compound stoichiometry. Similarly, dilute solutions, where the solute species is present in very low concentrations relative to the host solvent, can be handled in a relatively straightforward manner by assuming that the host material s density is not affected by the presence of the solute species. 

A mixture of metallic, covalent and ionic components prevails in the bonding of transition metal carbides, nitrides, and carbonitrides. The metallic character is shown by the high electrical conductivities of these compounds. The bonding mechanism has been described extensively by a variety of approaches for calculating the density of states (DOS) and hence the electron density in f.c.c. transition metal carbides, nitrides, and oxides [11]. In the DOS of these compounds there is a minimum at a valence electron concentration (VEC) of 8, which corresponds to the stoichiometric composition of the group ivb carbides TiC, ZrC, and HfC. Transition metal carbides have a lower DOS at the Fermi level than the corresponding transition metal nitrides, hence the electrical properties such as electrical and thermal conductivity and the superconducting transition temperature, T, are lower than those of the nitrides. 

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