Ostwald coefficient Table

TABLE 23. OSTWALD COEFFICIENTS (Z)/L OF O2AT latm IN AQUEOUS SOLUTIONS AT 25 C ... 

It will be seen from these tables that Henry s Law, when expressed in terms of the Ostwald coefficient k, holds over a much wider pressure range than when expressed in terms of k Up to 200 mm k remains constant within the limits of experimental error, and it will be observed, that at the same time the magnitude of the coefficient shows that the concentration of the dissolved gas becomes very considerable Using an empirical formula, Sackur and Stem have calculated with the aid of Hhese absorption coefficients the values of the osmotic pressure of the... 

TABLE 28. OSTWALD COEFFICIENTS (i)/L OF O2 AT latm IN AQUEOUS SOLUTIONS AT... 

Here, is the molar volume (the volume occupied by 1 mol of liquid) in liters, and p is the pressure in bar. Solubility data expressed by the Ostwald coefficient and by the mole fraction Xg are compiled in Table 10. TTie solubility decreases with increasing temperature. More data can be found in the reviews by Battino and Clever (1966) and Wilhelm and Battino (1973). 

Table 10 Solubility of Gases in Liquid Hydrocarbons at 25°C and a Gas Pressure of 1.013 bar L, Ostwald Coefficient X, Mole Fraction Solubility...

In Fig. 15 the R-lines are drawn on a common scale, and examples of Na values for 760 mm Hg and 25 C are registered on the 760 mm Hg horizontal. In Figs. 16-20 the Na values are registered on the 760 horizontal for each gas, and the probable pattern of the Na/Pa plots are indicated by broken lines. It is seen that the base-line scale (Na) must be reduced stepwise in passing from He to Rn in order to show the relative spread of the Na values. Figures 16-20 are based on Na data by Clever, Battino, Saylor, and Gross (1957) for the h series (hydrocarbons) (He to Kr), and by Saylor and Battino (1958) " for the b series (PhX X = F, Cl, Br, I, CH3) (He to Kr). Two points stand out from the tables in the papers cited. First, the Ostwald coefficient and mole fraction (Na) values do not correlate in two parallel series because the Na value depends upon the molecular weight and density of the liquid S and, second, the Na values for three temperatures ( h series) and for four temperatures ( b series) show that for He and Ne the Na value increases with increase in t°C for every S named. (See Table 6.)... 

Bearing in mind that the Henry s law constant was given as (vol. CO2/V0I. solution)/PCO2 the summary given in the abstract indicates that at low temperatures Henry s law was more nearly followed when the volume of gas was related to the volume of the solution rather than to the volume of the solvent. In Fig. 1551 have compared the vol. CO2/V0I. solution plot with that for vol. CO2/V0I. S for propanol and benzene at different pcoj and at 20°C. To convert vol. A/vol. S (Ostwald coefficient) data into Xa data, the density and molecular weight of the original liquid S are material factors. The statement that the solubility (vol./vol.) decreases with the increase in molecular weight of S, even if the liquids S are chemically related, is, on a molecular basis, invalid. See Table 45. 

Table 9.6 Ostwald coefficients for some representative gases ...

The inhalational anesthetics have distinctly different solubility (affinity) characteristics in blood as well as in other tissues. These solubility differences are usually expressed as coefficients and indicate the number of volumes of a particular agent distributed in one phase, as compared with another, when the partial pressure is at equilibrium (Table 25.3). For example, isoflurane has a blood-to-gas partition coefficient (often referred to as the Ostwald solubility coefficient) of approximately 1.4. Thus, when the partial pressure has reached equilibrium, blood will contain 1.4 times as much isoflurane as an equal volume of alveolar air. The volume of the various anesthetics required to saturate blood is similar to that needed to saturate other body tissues (Table 25.3) that is, the blood-tissue partition coefficient is usually not more than 4 (that of adipose tissue is higher). 

Derive a general expression for the Ostwald partition coefficient in terms of the excess chemical potential of the solute (component 2) in each of the two phases of interest. Table 3.1 gives free energies of hydration or excess chemical potentials for several n-alkanes in liquid water relative to the ideal gas at 25 °C. These free energies were computed from molecular simulations... 

The only tricky thing about Bunson and Ostwald solubility coefficients is that they represent a volume of gas per volume of solvent (not solution). Because gases increase the volume of the solution when they dissolve into it, a correction has to be made for this difference. The correction is significant and on the order of 0.14% (Weiss, 1971). The values presented in Table 3.6 have not been corrected for this effect, and since this is a potential point of confusion, we will use the Henry s Law coefficient most often in this book. 

Ostwald s Definition —The coefficient k is the ratio of the concentration of the C02 in the solution and m the gas space (This is obtained from the k value by employing, m addition, data for the density of the solution ) Both k and k are given m the following table... 

Table 3.1 shows some values of the Ostwald absorption coefficient y of argon in water and in some liquids. It should be noted that the solubility as measured by y is about an order of magnitude smaller in water compared with other solvents. Note, however, that the solubility of argon in ethylene glycol at 25°C is about 0.035, almost the same as in water Isee Ben-Naim (1968)]. 

Table 3.1. Ostwald Absorption Coefficient y for Argon in Water and in Some Organic Liquids at Two Temperatures ...

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