Determination of partial pressure

Figure 17.2. Determination of partial pressure of solute in its standard state.

Measurement of total pressure is insufficient for the characterisation of vacuum systems. Detailed information (system cleanliness, presence of leaks, etc.) can only be obtained by the identification of components present in the gas phase by means of residual gas analysis. Having established gas composition, however, the determination of partial pressures is relatively straightforward. 

Ratios of ionization cross sections are necessary for the pressure computation according to Eq. (2) since k also depends on the ionization cross section of the reference species. The substance used for the pressure calibration (method 1) should, therefore, also be selected in a way that the uncertainty arising from estimated ionization cross section ratios is minimized. Hiipert et al. [61] for example used Nal(s) instead of Ag(s) for the determination of partial pressures over phases of the Nal-Fel2 system. 

A blood gas analyzer for the determination of partial pressures, contents, and the Ot dissociation curve was constructed and tested. A membrane permeation cell was connected to the input of a mass spectrometer. During injection of the blood sample, the output of the analyzer was a function of the partial pressures. When injection ceased, gases were depleted from the blood sample. The area of the depletion curve was proportional to the original amount of gas in the sample. Any point on the depletion curve for 02 in blood could be transformed to a point on the Ot dissociation curve. 

Fig. 16. Diagram of determination of partial pressures of remaining constituents by the Dam-...

Fig. 17. Graphical determination of partial pressure values or the following approximation. Damkohler and Edse proceeded thus ...

Ac Che limic of Knudsen screaming Che flux relacions (5.25) determine Che fluxes explicitly in terms of partial pressure gradients, but the general flux relacions (5.4) are implicic in Che fluxes and cheir solution does not have an algebraically simple explicit form for an arbitrary number of components. It is therefore important to identify the few cases in which reasonably compact explicit solutions can be obtained. For a binary mixture, simultaneous solution of the two flux equations (5.4) is straightforward, and the result is important because most experimental work on flow and diffusion in porous media has been confined to pure substances or binary mixtures. The flux vectors are found to be given by... 

An Instrument for Determining the Partial Pressure of Oxygen in a Gas1... 

C05-0037. A weather report gives the current temperature as 18 °C and sets the dew point at 10 °C. Using data from Table 5A, determine the partial pressure of water vapor in the atmosphere and calculate the relative humidity. 

Plan (1) Determine the partial pressure of acetic acid, CH3COOH, and carbon dioxide, C02, in the mixture. 

Mass spectrometry techniques are the most usual and versatile methods for analysis of the gas [90], Here the effusing vapour is ionized by an ionization source and the product analyzed with a mass spectrometer. The different vapour species are identified and the partial pressures of all species determined. The partial pressure of species i of a compound or a solution with a specific composition is at a specific temperature ... 

A sample of methane gas was collected over water at 35°C. The sample was found to have a total pressure of 756 mm Hg. Determine the partial pressure of the methane gas in the sample (vapor pressure of water at 35°C is 41 mm Hg). 

There is some air that is 2 ppm(v) methane. Determine the partial pressure of methane at an atmospheric pressure of 1 atm. 

In this equation, fugacities were used instead of partial pressures, to take into account the nonideal behaviour of gases at high pressure. The coefficients, A to E, were determined by means of non-linear regression calculation by a method of Marquardt [25], From the measurements at various temperatures, the frequency factor, k0, and the activation energy, E, were evaluated. The data are collected in Table 3.3-1. 

For a measure of amount of water relevant to stability concerns, vapor pressure, or its related thermodynamic parameters, is more relevant. Determination of vapor pressure uses methods developed from thermodynamic roots, though if the product is not at true equilibrium, the measured quantity is not a thermodynamic descriptor of the product, although it is still a measure of a product characteristic. Water mobilities are often inferred from spectroscopic measurements of relaxational phenomena. Many workers attempt to identify different classes of water characteristic of different ranges of water content and water partial vapor pressure. Spectroscopic measurements, too, are often interpreted in terms of populations of water molecules with similar characteristics. 

The method determines the partial pressure of methane in the gas phase above the solution (Henry s law). Methane catalytically oxidizes on a heated platinum filament, that is part of a Wheatstone bridge. The heat generated increases the electrical resistance of the filament which is measured and compared against calibrated standards. 

C, the vapor pressure of methanol is 94 torr and that of ethanol is 44 torr. (a) Determine the partial pressure exerted by each component in a solution containing 20 g CH3OH and 100 g C2H5OH. (b) What are the mole... 

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