Saturation pressure of pure liquid

Table I and Figures 1-4 contain a wealth of information about the solubilization of benzene in aqueous surfactant micelles. Plots of K vs. Xg exhibit shallow minima in the case of the SDS solutions, and rather more pronounced minima for the CPC solutions. The plots of Tg vs. Xg show corresponding maxima, reflecting the fact that K and Yg are related reciprocally by K l/(TBcB ), where cB° is the monomer concentration of benzene in the aqueous phase at saturation. (The minimum in K and the maximum in Yg for the CPC solutions, shown in Figure 1, are not quite reached at the benzene concentrations attainable with the automated vapor pressure apparatus. The automated apparatus is restricted to operating at partial pressures less than about 70% of the vapor pressure of pure liquid benzene. However, the manual apparatus can be used for measurements almost to saturation, and results obtained with this apparatus show extrema in K and Yg at approximately X = 0.55.)...

Relative humidity %RH, lOOP/Po, IOOjc The vapor pressure of water in the atmosphere (P) usually expressed as a percentage of the saturation vapor pressure of pure liquid water (R,) at the same temperature. 

Saturation vapor pressure of pure liquid sorbate (Eq. 20) Adsorbed-phase concentration Saturation limit (Eq. 5)... 

Yi mole fraction of component i in the gas phase mole fraction of component i in the liquid phase P°i(T) saturation pressure of pure component i at the system temperature T... 

In addition to marking the phase boundary, line FC expresses the relationship between saturation pressure and temperature. The saturation pressure generally increases quickly with temperature up to the critical point. There is no vapor-liquid transition above the critical point therefore, the relationship between saturation pressure and temperature exists only below the critical point. The saturation pressure of pure component is an important physical property and a required parameter in many calculations of phase equilibria. Several equations have been developed to describe the mathematical relationship between saturation pressure and temperature. One of the most widely used is the Antoine equation ... 

This equation states that the partial pressure of water vapor in the presence of liquid water is equal to the saturation pressure of pure water at this temperature. Equation along with the normalization condition. 

The adsorption isotherm for nitrogen on silica gel is recorded at 77.3° K in the low pressure region pfp from 0 to about 0.25 (po = saturation vapour pressure of pure liquid nitrogen at 77.3° K p = vapour pressure of the nitrogen adsorbed on the silica gel). 

Suppose that we vary the composition of the solution in system 1 at constant temperature, while adjusting the partial pressure of C so as to keep p constant. If we find that the partial pressure of the solvent over a range of composition is given by pa = XapX where p is the partial pressure of A in system 2 at the same T and p, we will say that the solvent obeys Raoult s law for partial pressure in this range. This is the same as the original Raoult s law, except that p is now the vapor pressure of pure liquid A at the pressure p of the liquid mixture. Section 12.8.1 will show that unless p is much greater than p is practically the same as the saturation vapor pressure of pure liquid A, in which case Raoult s law for partial pressure becomes identical to the original law. 

Here is the vapor pressure of pure liquid solute at the same temperature and total pressure as the solution. If the pressure is too low for pure B to exist as a liquid at this temperature, we can with little error replace with the saturation vapor pressure of liquid B at the same temperature, because the effect of total pressure on the vapor pressure of a liquid is usually negligible (Sec. 12.8.1). If the temperature is above the critical temperature of pure B, we can estimate a hypothetical vapor pressure by extrapolating the liquid-vapor coexistence curve beyond the critical point. 

Table 12.5 gives values of physical quantities at T = 298.152 K needed for this problem. The values of xb and ( / U ) were obtained by Rettich et al from samples of liquid and gas phases equilibrated at temperature T, as explained above, is the saturation vapor pressure of pure liquid water at this temperature. 

You wish to determine the fugacity of a in a liquid mixture with 1 mole of a and 4 moles of b at 30 kPa and 20°C. At this temperature, the saturation pressure of pure a is 50 kPa. The excess Gibbs energy for a mixture of a andb has been lit to the following relation ... 

Using the Peng-Robinson equation of state, calculate the saturation pressure of pure n-pentane at 400 K using fugacity coefficients to calculate the fugadty for both vapor and liquid phases. Compare the results with the values of Ff obtained by the Antoine equation and report the percent error. 

For continuous systems, molar flow rates Q can be used instead of n. The thermodynamic activity (ax) can be calculated according to Equation 2, but requires knowledge of the saturation pressure of the pure compound (Ppsatx). This data can be obtained from the saturation curves (vapor-liquid equilibrium curves) and is taken at the working temperature of the gas stream. The thermodynamic activity is then calculated using the following equation ... 

The isothermal vaporization of pure liquid i represents its transition from saturated liquid to saturated vapor at temperature T and at saturation vapor pressure P8 6. The treatment of this transition is facilitated through use of property changes of vaporization defined by equation 139 ... 

The vapor pressures of the pure liquid components are replaced by the vapor pressures of the liquids saturated with salts. The Wilson equation (5) in its three-constant form is employed as the correlating equation. This yields values of A21, A12, and C and the corresponding vapor compositions. 

Component a making up a liquid phase (L) in contact with a gas phase (G) forms a two phase system. In the equilibrium state, the chemical potential of component a in the gas and contacting phase are equal. The equilibrium saturated vapor pressure of pure component a in the gas phase over the pure liquid phase a can be designated with p. Using the expression for a perfect gas, Eq. (4-1), for the chemical potential of a, one gets an expression of the chemical potential of component a in liquid a, p (L), in the equilibrium state ... 

Consider now that some adsorption of liquid vapours on the solid surface occurs (Figure 1,34.b), leading to a reduction of its surface energy by a quantity Aliquid surface). For the sake of clarity, we denote by cr< v and W the solid surface energy and the work of adhesion in the absence of adsorption, while pure solid/pure liquid/vapour system held at constant temperature, the solid surface is in equilibrium with a saturated vapour of the liquid at a partial pressure of Psat, the equilibrium values of [Pg.45]

When any pure gas (or a gaseous mixture) comes in contact with a liquid, the gas will acquire vapor from the liquid. If contact is maintained for a considerable length of time, vaporization continues until equilibrium is attained, at which time the partial pressure of the vapor in the gas will equal the vapor pressure of the liquid at the temperature of the system. Regardless of the duration of contact between the liquid and gas, after equilibrium is reached no more net liquid will vaporize into the gas phase. The gas is then said to be saturated with the particular vapor at the given... 

PHASE EQUILIBRIA. In humidification and dehumidification operations the liquid phase is a single pure component. The equilibrium partial pressure of solute in the gas phase is therefore a unique function of temperature when the total pressure on the system is held constant. Also, at moderate pressures the equilibrium partial pressure is almost independent of total pressure and is virtually equal to the vapor pressure of the liquid. By Dalton s law the equilibrium partial pressure may be converted to the equilibrium mole fraction in the gas phase. Since the liquid is pure, is always unity. Equilibrium data are often presented as plots of Pg vs. temperature at a given total pressure, as shown for the system air-water at 1 atm in Fig. 23.1. The equilibrium mole fraction y is related to the saturation humidity by Eq. (23.2) thus... 

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