Vapor pressure, table

For any industrial process involving vapors and Hquids, the most important physical property is the vapor pressure. Table 1 presents values for the constants for a vapor-pressure equation and the temperature range over which the equation is vaHd for each butylene. 

This shows that the presence of air in the gas phase has a very small influence on the vapor pressure of water. Repeating the same calculation procedure for other temperatures, we can show that the vapor pressure of water can with good accuracy be taken from the vapor pressure tables for saturated water (water has the same pressure as water vapor when they are in equilibrium), as though there were no air in the gas phase. So the vapor pressure of water is with good accuracy also in this case just a function of temperature, and Eq. (4.97) is valid. New vapor pressure tables will not be needed for calculations with humid air. 

From steam tables (or fluid vapor pressure tables), read at 24.98 psia (for w ater of this example), temperature = 240°F. 

To understand vapor pressure, let s consider an empty jar that is partially filled with water and then covered with a lid. We will assume the space above the water in the jar contains only air when we screw on the jar s lid. After the lid is place on the jar, water molecules leave the liquid and enter the air above the liquid s surface. This process is known as vaporization. As time goes by, more water molecules fill the air space above the liquid, but at the same time, some gaseous water molecules condense back into the liquid state. Eventually, a point is reached where the amount of water vapor above the liquid remains constant. At this point, the rates of vaporization and condensation are equal, and equilibrium is reached. The partial pressure exerted by the water at this point is known as the equilibrium vapor pressure or just vapor pressure. Vapor pressure is directly related to the temperature, that is, the higher the temperature, the higher the vapor pressure. Table 9.4 gives... 

In investigating the reaction of oxygen atoms with isobutene, analysis for propene was carried along with that for carbonyl compounds and CO. Propene was separated from isobutene at —112° to about — 115°C., which was possible due to the sufficient difference in vapor pressures (Table III). Experimental results have shown that the amounts of for-... 

Any substance which may be obtained pure and for which accurate vapor pressure data are available may be used for vapor pressure thermometry. Stock recommended a convenient series of compounds and, in collaboration with Hen-nig and others, he obtained accurate vapor pressure data for these compounds.15 These data were obtained on a temperature scale for which 0°C = 273.1K however, more recent data on several of the compounds show it would be difficult to improve on Stock s vapor pressure tables. When high accuracy is desired, the usual precautions involved in precise manometry (Chapter 7) must be observed. 

Because of great differences in their vapor pressures(Table HE), differences in the process variables originating from carbon number distribution of raw materials are relatively great in this process, especially in the oxidation step. A comparison is summarized in Table IV, which shows the disadvantage of a lower carbon number range to some extent. 

Organic compounds—Tables. 2. Vapor pressure—Tables. 

Redundant measurement means obtaining the same process information with two like measurements or two measurements using different principles. Redundant measurements can be calculated or inferred measurements. Two like measurements would be two pressure transmitters, two temperature measurements, two level measurements, and so on. An example of inferred measurement would be using a pressure measurement and vapor pressure tables to check an actual temperature measurement. 

Until recently, only three chlorofluorocarbon (CFC) propellants, namely CFCs 11, 12 and 114 (Table 1), had been approved worldwide for use in medical MDIs. Their widespread acceptance was due to their ability to substantially meet the ideal propellant properties. All the CFC MDIs that are currently marketed employ CFC 12 as the major constituent mixed with either CFC 11 or with a mixture of CFC 11 and CFC 114. These mixtures of propellants closely obey Raoult s law and therefore the blend selected can be used to give a defined vapor pressure (Table 1). The inclusion of CFC 11 in the formulation also offered advantages in that it increased the solvency of most propellant systems, thereby facilitating the dissolution of surfactants in suspension formulations. By virtue of it being a liquid below 24° C, it was used as the primary dispersion medium for either suspending or dissolving the drug. 

Compare this result with TCE volatilization shown in Examples 2-6 and 2-7. Although benzene and TCE have similar vapor pressures (Table 1-3), benzene... 

The Kelvin equation can be combined with the relative humidity, RH, if water is involved as the fluid relative humidity indicates how moist the air is. The amount of water vapor in the air at any given time is usually less than that required to saturate the air. The relative humidity is the percentage of saturation humidity, generally calculated in relation to the saturated vapor density. Relative humidity may be defined as the ratio of the water vapor density (mass per unit volume) to the saturation water vapor density, usually expressed in percent. Relative humidity is also approximately equal (exactly equal when water is assumed as an ideal gas) to the ratio of the actual water vapor pressure to the saturation water vapor pressure, RH = PJP°. The P° values corresponding to each temperature are given in tables which can be found in handbooks. If RH is measured in an experiment, then Pv can be calculated by using the saturation water vapor pressure tables and can be inserted into the Kelvin equation. 

B7. Brooks, A. A., and P. Wood Vapor Pressure Tables for Liquid Uranium Hexafluoride, Report K-722, Nov. 21, 1957. 

Removed can be calculated from vapor pressure table in 90 Ed., p. 6-5... 

The vapor pressures tables. of toluene and n-heptane are given Vapor pressure of n-heptane 1 in the accompanying ... 

Dew point temperature=55° at 200 psig From vapor pressure table— P =.2130... 

Table B-1 SI Measurement Table B-2 Unit Symbols Table B-3 Symbols Table B-4 Physical Constants Table B-5 Enthalpy of Combustion Table B-6 The Elements Symbols, Atomic Numbers, and Atomic Masses Table B-7 Common Ions Table B-8 Water-Vapor Pressure Table B-9 Densities of Gases at STP Table B-10 Density of Water Table B-11 Solubilities of Gases in Water Table B-12 Solubility Chart Table B-13 Solubility of Compounds Table B-14 Enthalpy of Formation Table B-15 Properties of Common Elements...

The relative humidity of a water vapor-air mixture is defined mixture is cooled from an initial temperature t. This table gives as 100 times the partial pressure of water divided by the satura- relative humidity as a function of the dew point depression t -tion vapor pressure of water at the same temperature. The rela- for several values of the dew point. Values are calculated from the tive humidity may be determined from the dew point which vapor pressure table in Section 6. is the temperature at which liquid water first condenses when the... 

The vapor pressure data for solids is often shown inconspicuously in handbooks. For example, in the vapor pressure tables in [12, p. 2.58] the values for elemental iodine are shown as a row in the table (see Table ll.A). From the value in the rightmost column we see that the four rightmost values are the vapor pressure of pure hquid iodine (above the melting point) and the five leftmost values are the vapor pressures of pure solid iodine. 

Compare this result with TCE volatilization from a lake or river, shown in Examples 2.6 and 2.7. If the dissolved TCE concentrations in the lake or river had been in equilibrium with NAPL-phase TCE (i.e., 1000 mg/liter), the water to air fluxes would be 10 times greater than shown in the examples. Nevertheless, benzene would stiU evaporate from a slick approximately 100 times more rapidly than dissolved TCE would volatilize from a surface water, despite benzene and TCE having similar vapor pressures (Table 1.3). 

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