Constant of Normal and Heavy Water

IONIZATION CONSTANT OF NORMAL AND HEAVY WATER Serguei N. Lvov and Allan H. Harvey... 

Combustion. The primary reaction carried out in the gas turbine combustion chamber is oxidation of a fuel to release its heat content at constant pressure. Atomized fuel mixed with enough air to form a close-to-stoichiometric mixture is continuously fed into a primary zone. There its heat of formation is released at flame temperatures deterruined by the pressure. The heat content of the fuel is therefore a primary measure of the attainable efficiency of the overall system in terms of fuel consumed per unit of work output. Table 6 fists the net heat content of a number of typical gas turbine fuels. Net rather than gross heat content is a more significant measure because heat of vaporization of the water formed in combustion cannot be recovered in aircraft exhaust. The most desirable gas turbine fuels for use in aircraft, after hydrogen, are hydrocarbons. Fuels that are liquid at normal atmospheric pressure and temperature are the most practical and widely used aircraft fuels kerosene, with a distillation range from 150 to 300 °C, is the best compromise to combine maximum mass —heat content with other desirable properties. For ground turbines, a wide variety of gaseous and heavy fuels are acceptable. 

Enzymatic reactions conducted in heavy water frequently proceed with rate constants that differ from those of reactions in normal water, and the ratio of these rate constants, or the solvent deuterium... 

An alternative pathway to bicarbonate is possible due to reaction of CO2 and OH in water but is normally less important (Skirrow, 1975). The proton concentration is also inbuenced by total alkalinity and water dissociation, which, in turn, will inbuence the details of the simplibed chemical process depicted above. The relative concentrations of the DIC species in Equation (15) are mainly a function of pH, temperature, and salinity. In seawater, bicarbonate is the dominant species (Skirrow, 1975), and bicarbonate and carbonate are the main components of alkalinity (Broecker and Peng, 1974). The chemical equilibrium for each of the steps in the DIC system in Equation (15) is determined from the specibc temperature sensitive reaction constants (Aix). Note that in the complex system of seawater, empirical Kj values, rather than thermodynamic theoretical values, are usually adopted. Such reacbon constants are of course sensitive to the effects of molecular mass, with molecules containing heavy isotopes favoring slower reactions rates, and are therefore associated with temperature-sensitive isotopic fractionations. Typical equilibrium fractionation values for the carbonate system in dilute solution at 25 °C are (Deuser and Degens, 1967 Mook, 1986 Mook et al., 1974) ... 

The equilibrium equations that normally have to be considered in the EKR modeling of a soil contaminated by heavy metals can be classified into one of the following categories complex formation reactions, precipitation of the metal hydroxides or of other species, ion exchange reactions, surface complexation reactions, etc. Anyway, the autoionization of water always has to be considered and the precipitation of carbonates, together with the carbonate-bicarbonate equilibrium, should normally also be considered. However, the above equations have only considered the species in aqueous phase, so if a species precipitates, a new master species has to be included in this equilibrium system, whose concentration would be the amount of the precipitated species per unit volume of water. This additional degree of freedom is constrained by the solubility product constant of the precipitate (KO, because the new solid phase is in equilibrium with the aqueous phase. If there exists Np precipitated species, the pure-phase equilibria can be represented with the following equation ... 

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