Pressure of saturation

The partial pressure of water vapor in air cannot be higher than the vapor pressure of saturated water ft (T) corresponding to air temperature T. If it were higher, condensation of water vapor would occur until the equilibrium state corresponding to the saturated vapor pressure was achieved. 

A simpler approximation for the pressure of saturated water vapor is... 

Critical relative humidity The primary value of the critical relative humidity denotes that humidity below which no corrosion of the metal in question takes place. However, it is important to know whether this refers to a clean metal surface or one covered with corrosion products. In the latter case a secondary critical humidity is usually found at which the rate of corrosion increases markedly. This is attributed to the hygroscopic nature of the corrosion product (see later). In the case of iron and steel it appears that there may even be a tertiary critical humidity . Thus at about 60% r.h. rusting commences at a very slow rate (primary value) at 75-80% r.h. there is a sharp increase in corrosion rate probably attributable to capillary condensation of moisture within the rust . At 90% r.h. there is a further increase in rusting rate corresponding to the vapour pressure of saturated ferrous sulphate solution , ferrous sulphate being identifiable in rust as crystalline agglomerates. The primary critical r.h. for uncorroded metal surfaces seems to be virtually the same for all metals, but the secondary values vary quite widely. 

Total (standard) pressure = 1013.25 mbar Partial pressure of saturated vapour = 31.66 mbar... 

Dissolution is endothermic, solution becomes cold (and hence its apphca-tion in freezing bath) elevates the boiling point of water by 1°, 7.5°, 28.5° and 70°C at 10, 40, 80 and 95% (w/w) concentrations, respectively vapor pressure of saturated solution, 11.2 torr at 20°C. 

The most frequently used calibration procedure is based on temperature dependence of pressure of saturated mercury vapour [19,39-41]. At 25°C this pressure is of 0.0018 mm Hg height it corresponds to the vapour density of 20 pg/1. To get in the measurement cell a mercury concentration of about 10 ng/1, the saturated vapour should be strongly diluted. Instead of dilution, a lower temperature can be used however, the density of saturated vapour of 10 ng/1 corresponds to the temperature of less than —40°C. Both dilution and temperature decrease can be realized easily in laboratory conditions but their incorporation into a miniaturized chemical sensor is rather complicated. An attempt to develop such a device is reported in Ref. [41]. An additional problem in application of these techniques in portable sensing devices with integrated calibration is the necessity to have a reservoir with mercury in the device it complicates recycling of these devices and does not correspond to modern trends in technology. 

Ethylchloride is a colourless liquid with a pleasant odour (the boiling point is 12.5°C, the solidification point is -138.7 °C) it is combustible. The pressure of saturated ethylchloride vapours is 0.113 MPa at 15°C. Its evaporation heat is 387 KJ/kg. It dissolves well in organic solvents and only to some extent in water (100 g water at 0°C dissolve only 0.45 g of ethylchloride). 

Ravich MI, Borovaya FE, Ketkovich VYa. Solubility and vapor pressure of saturated solutions in the KC1-K2S04 H20 system. Izv Sekt Fiz-Him Anal Inst Obs Neorg Him Im NS Kurnakova 1953 22 225. 

At 20° the concentration of saturated water vapor is such that its pressure is 17.4 mm. At other temperatures the concentration is different, but it has an absolutely definite value for each temperature. The pressure of saturated water vapor has been carefully measured at different temperatures. The values from 0° to 100° are given in the table on page 353 in the Appendix. 

The amount of heat required to convert 1 g. of a pure liquid into saturated vapour at any given temperature (or pressure, since the pressure of saturated vapour is a function only of temperature) is called the latent heat of evaporation (sometimes latent heat of vaporisation), denoted by 4. It is usually understood to apply to evaporation at the normal b.p. at 1 atm. pressure, and it varies rather considerably with temperature. For water ... 

If wb consider a solution of given concentration s, at each temperature it will have a well-defined pressure of saturated vapor if, on the two rectangular coordinate axes sOT, On (Fig. 53)... 

At the temperature T, let Pj and Pj be the pressure of saturated vapors of the liquids 1 and 2 taken in the state of purity suppose also that the liquid 1 be more volatile than the liquid 2, so that Pj exceeds Pj. 

PRESSURE OF SATURATED WATER VAPOUR IN EQUIRIBLIUM WITH WATER AT VARIOUS TEMPERATURES, DEGREES CELSIUS... 

The temperatures and pressures of saturated steam have a two-way correlation. Once the... 

Diffuse-reflectance IR spectra were measured in the spectral range of 4000 -1800 cm l using a Perkin-Elmer 580 B spectrophotometer supplied with a diffuse-reflectance attachment [10]. Trifluoromethane, chloroform, acetylene, methylacetylene, phenylacetylene, diethylacetal of propargylaldehyde were used as probe-molecules for basic centers in the zeolites under study. The substances were adsorbed at room temperature either from the gas phase at a pressure of 1-30 torr or from the vapor phase at a pressure of saturated vapors. 

Fig. 23.5 Effect of pressure of saturated steam on rate of dyeing of Nylon 66 (Peters and White, J.S.D.C., mi, COI)...

CALL THE PROGRAM TO CALCULATE THE VAPOR PRESSURE OF SATURATED LIQUIDS (PAGE 214 Yaws et. al.)... 

Micka and Ebert [861VI1C/EBE2] measured the water vapour pressure of saturated solutions in the system K2Se03-H2Se03-H20. From these measurements they calculated the selected Gibbs energy of the reaction ... 

Abstract The behavior of the self diffusion coefficient in simple liquids under pressure is discussed. It is taken into account that the self-diffusion coefficient is the sum of the collective and one-particle contributions. From our reasons it follows that the collective contribution monotonously increases with pressure. The comparison with the computer simulation data for the full self-diffusion coefficient of argon shows that the relative value of the collective part increases from 0.2 for the pressure of saturated vapor up to 0.76 and larger for pressure 10 GPa. 

Many authors have tried to derive the enthalpies of the gas-phase reactions (Eq. 1) as well as the entropies S° of the various S molecules for n=2-8 from the temperature dependence of the mass and Raman spectra in combination with the total pressure of saturated and unsaturated sulfur vapor. These results are summarized in Table 1 and will be commented on in detail in the following sections. Most authors assumed that only one species is present for each molecular size in other words, possible isomers were neglected. It has later been found out that this is an oversimplification (see below). 

It) rePresents e c ange m vapour pressure of the liquid per degree rise in temperature Since, however, we know that the pressure of saturated vapour is independent of the volume of the vapour so long as any liquid is present, we need not retain the restnction of constant v in this case, but may simply write—... 

Expressions for the Pressure of Saturated Vapour [in contact with Liquid) and the Heat of Vaporisation... 

---