Bunsen coefficients

The narcotic potency and solubiUty in oHve oil of several metabohcaHy inert gases are Hsted in Table 10. The narcotic potency, ED q, is expressed as the partial pressure of the gas in breathing mixtures requited to produce a certain degree of anesthesia in 50% of the test animals. The solubiUties are expressed as Bunsen coefficients, the volume of atmospheric pressure gas dissolved by an equal volume of Hquid. The Hpid solubiHty of xenon is about the same as that of nitrous oxide, a commonly used light anesthetic, and its narcotic potency is also about the same. As an anesthetic, xenon has the virtues of reasonable potency, nonflammability, chemical inertness, and easy elimination by the body, but its scarcity and great cost preclude its wide use for this purpose (see Anesthetics). 

For pressure effects, the Bunsen coefficient is used and is calculated from the equation as follows ... 

In addition, when using semiconductor sensors for measuring concentration of oxygen in carrier gases, or in liquid media, one can also determine the relative contents of oxygen in a liquid and in saturated vapour over its surface (the Bunsen coefficient). 

For this purpose, one should measure variation of electric conductivity of one and the same movable sensor in the saturated vapour-gas phase and in a liquid, caused by the presence of any given concentration of oxygen in a carrier gas (hydrogen, nitrogen, noble gas, etc.). From the results of these measurements the Bunsen coefficient P can be found in accordance with the relation (see Chapter 3, Section 4)... 

The latter formula enables one to estimate the Bunsen coefficient using a semiconductor sensor. 

Dass association constant for ion pair formation Dbs Bunsen coefficient for solubility of gas in a liquid... 

There are several ways of expressing the solubilities of gaseous species in melts or hquids. The Bunsen coefficient defines the volume of reduced gas at T = 273.15 K, P = 1.013 bar adsorbed by a unit volume of solvent at T of interest and P = 1.013 bar. The equation used to calculate the Bunsen coefficient is... 

Bunsen coefficient 13 (dimensionless) Normal Volume of ozone (calculated for STP) dissolved per volume of water at T, when the partial pressure of ozone in the gas phase is one standard atmosphere (= 101 325 Pa) (273.15 K/T) He... 

Bunsen coefficients -of gases [HELIUM GROUP - GASES] (Vol 13)... 

Weiss (1970a) reviewed and evaluated the literature data then available for N2, 02, and Ar and fitted them to a smooth functional dependence. His results are reported in terms of the Bunsen coefficient j5, defined as the quantity of gas (in cm3 STP) dissolved in unit volume (1 cm3) under unit partial pressure (1 atm). Pure water data were fitted to an integrated van t Hoff equation ... 

The units used to express solubilities of gases, e.g. Henry s law coefficients, Ostwald coefficients and Bunsen coefficients, have to be converted to the relevant solution standard state (p. 213). Such solubilities (Battino and Clever, 1966 Wilhelm and Battino, 1973) are valuable in the analysis of kinetic data. For example, the solubility of a neutral solute in a range of aqueous mixtures can provide some indication of the variation of the chemical potential of a neutral reactant because, from eqn (11), 8m AGe = 8mnf. Where the pure solute is a liquid or solid, it is often convenient to chose the pure solute as a standard state, represented by the symbol, ° in eqn (12). Similar comments apply to the related thermodynamic quan-... 

The solubility was expressed in terms of the Ostwald absorption coefficient, L, which is defined as the ratio of the volume of absorbed gas to the volume of absorbing liquid at the temperature and pressure of the measurement. This is because the Ostwald coefficient is really an equilibrium constant, and the method of correction to standard conditions does not need to be specified in comparison with the Bunsen coefficient. 

TABLE 22. BUNSEN COEFFICIENTS (P) OF GASES AT latm IN ORGANIC SOLVENTS AT 20 C ... 

The solubility of the gas in the liquid the Bunsen coefficient defines the volume of gas which dissolves, at STP, in a unit volume of solvent at one atmosphere gas pressure. 

For photolysis at 1470 A. a combination Xe arc and reaction cell (15) was used. The light flux through the sapphire exit window was about 8 X 10"9 Einsteins/sec. The actinometer used was the photolysis of cyclohexane for which < (H2) has been shown to be 1.0 (25). In die cell the solutions were in contact with the sapphire window. Solutions were photolyzed for — 20 min., and the conversion was approximately 0.1%. The solutions were stirred during photolysis and cooled to 13 db 2°C. to prevent evaporation. The concentration of nitrous oxide in the liquid phase was calculated from the Bunsen coefficients of 3.3 for cyclohexane and n-hexane and 3.8 for 2,2,4-trimethylpentane (26). 

Yet, none of these units is common in the literature on gas solubilites. For the determination of gas solubilities in controlled lab experiments, often a pure gas phase at known pressure (usually 1 atm) is brought into contact with a known mass or volume of the solvent (e.g., pure water). A convenient way to express gas solubilities is then the Bunsen coefficient Pi, which is the volume of gas i at STP adsorbed per volume of solvent if the gas pressure pi is 1 atm. Alternatively, the so-called mole fraction solubility Xi states the mole fraction of gas i in the solution at equilibrium with the pure gas at 1 atm. In field samples one usually determines the amount of dissolved gases per mass of solution. 

The Bunsen coefficients, a, and the standard deviation among a number of tests performed under identical conditions are presented. The Bunsen coefficient is defined as the gas volume at STP (0.101 325 MPa and 273.15 K) absorbed per unit volume of pure liquid at the temperature of the measurement. All data refer to a temperature of 310.2 K and a pressure of 0.101 325 MPa. 

Dissolving a gas in a liquid is an exothermic process. Assuming an ideal gas, account for this in terms of molecular forces. Suggest a molecular explanation of the Bunsen coefficient a increase with increasing gas boiling point. 

The value of the Sechenow coefficient, as well as the solubility and Bunsen coefficients, depends on temperature. This is why attempts were undertaken to express the correlation of Bunsen solubility coefficient vs. temperature and salinity by one common equation. For instance, Ray Weiss (1970) gathered published data on solubility, put them into one dimension and using the least square technique came up with empiric exponential series of the correlation between Bunsen solubility coefficient (mole-k bar"0 vs. temperature and water salinity ... 

There are other ways of accounting for the effect of water salinity. Ray F. Weiss proposed to use for the sea water directly the empiric equation (2.291), whose constants are presented in Table 2.30. And lastly, the Z. Duans group, combining the Pitzer equation (2.292) and equations of real gas solution state, calculated Bunsen coefficients for O, N, CH, H S and CO in conditions of temperature between 0 and 200-300 °C, pressure of 1 to 200-2,000 bar with NaCl content of 0 to 6 mole-kg" (Duan et at, 2006 Duan et al, 2007 Mao and Duan, 2006 Geng and Duan, 2010). However, their values are noticeably different from experimentally derived under high temperature. 

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