Pure vapor pressure

Raoult s law states that the partial pressure (P ) is equal to the product of the pure vapor pressure (P°) and the mole fraction (X) of the component being considered as follows [29] ... 

Vapor pressure lowering. Raoult s law says that the vapor pressure of a solution component, A, whose pure vapor pressure is P is proportional to... 

Pj is called the partial pressure of species i in the vapor mixture and Pisat denotes the pure vapor pressure of the component i at the solution temperature. 

As shown by Rault s law and Henry s law, the partial vapor pressure of a solution component is always proportional to its mole fraction. If the component predominates as Hie solvent, Rault s law says that the partial vapor pressure is proportional to the pure vapor pressure. If the component represents a tiny amount of solution. Henry s law says that the vapor partial pressure is proportional to Benny s irw constant. 

Let PA,pure = vapor pressure of pure A and PB,pure = vapor pressure of pure B. 

Liquefied gases operate under the principle of Raoult s Law, which states that the total pressure of a system is equal to the sum of the partial pressures of the volatile ingredients. The partial pressure of each ingredient is equal to the mole fraction of that ingredient in the mixture times its own pure vapor pressure. The equation becomes... 

The separate liquid-water phase exerts a partial pressure equal to its pure vapor pressure. Thus, pw = Pw = 12.3 kPa. Extending (3-4), the total pressure is... 

For a pure liquid at 350 K and having a molar volume v = 0. liter/mol, estimate the pressure at which the Poynting factor deviates by 2% from unity. For the pure vapor pressure at 350 K, use P = 0.1 MPa. 

Figure 9.8 Pressure-temperature diagram for the alkane(l)-aromatic(2) mixture in Figures 9.4-9.7. Solid lines are pure vapor-pressure curves, ending at pure critical points (filled circles). Dashed line is the mixture critical line. Dash-dot lines are liquid constant-composition lines small dashed lines are vapor constant-composition lines. Filled square at A is a vapor-liquid equilibrium point it occurs at 14.5 bar, 386.7 K, Xj = 0.25, t/j = 0.75.

Figure 9.22 Schematic PT diagrams for the five major classes of binary fluid mixtures. Large dots are pure vapor-liquid critical points dashed lines are pure vapor-pressure curves. Solid lines starting from the pure, high-pressure critical point are mixture vapor-liquid critical lines other solid lines are mixture liquid-liquid critical lines. Small dots are upper (U) and lower (L) critical end points dash-dot lines are three-phase VLLE lines. Diagrams shown here are representative of the classes, but they do not exhaust the possibilities.

Figure 10.1 When computed from an analytic equation of state using FFF 1, the fugacity vs. composition curve may change significantly with state condition. Top PT diagram for a binary mixture. Filled circles are pure critical points vpl and vp2 are pure vapor-pressure curves cl = critical line mcl = mechanical critical line. Bottom Corresponding fugacity of the more volatile component at 275 K. Broken lines are vapor-liquid tie lines. Isobars at bottom correspond to open circles at top. Bottom same as Figure 8.13. Computed from Redlich-Kwong equation.

If a value for a pure-component fugadty cannot be obtained at the mixture pressure P, then one may be available at the pure vapor pressure P (T). In such cases we use a Poynting factor to correct the known fugadty to the system pressure. 

Standard states for liquids. For a liquid species i, the standard state is usually taken to be the pure liquid at the equilibrium temperature T and at the pure vapor pressure P° = Pi(T). Then the standard-state fugacity becomes... 

When the standard-state pressure P- and the pure vapor pressure P are both low, then the liquid enthalpies are essentially the same at both pressures likewise for the vapor enthalpies. Then we have this approximation... 

Figure 12.19 Effect of temperature on fugacity of a pure saturated liquid. Vapor-phase nonidealities (cpf) lower from the pure vapor-pressure curve, but the variation of /j-"with 1/T remains roughly linear. At supercritical temperatures, jnue vapor pressures do not exist nevertheless, for (0.9 < r /T < 1), we may choose the hypothetical pure liquid for the standard state and obtain a value of f° by extrapolation. These values were comjnited for pure water using data from steam tables [14].

The system benzene-toluene follows Raoult s law, so the boiling-point diagram can be calculated from the pure vapor-pressure data in Table 11.1-1 and the following equations ... 

Heptane (pure vapor pressure = 92.0torrat 40°C) Is a more volatile liquid than octane (pure vapor pressure =... 

Donahue NM, Trump ER, Pierce JR, Riipinen I (2011) Theoretical constraints on pure vapor-pressure driven condensation of organics to ultrafine particles. Geophys Res Lett 38 L16801... 

According to RaouUi law, the partial pressure of a substance ov a solution is equal to the mole fraction (j() of the substance times its pure vapor pressure iP°). An ideal solution is one that ob Raonit s law. 

FIGURE 7.4 The total pressure of an ideal liquid solution is a smooth transition from one pure vapor pressure to the other. 

FIGURE 7.5 The mole fractions in the vapor phase are not the same as in the liquid phase. The bubble point line gives total pressure versus liquid-phase mole fraction, x,. The dew point line gives total pressure versus vapor-phase mole fraction, y,. The two lines would coincide only if both components had the same pure vapor pressure. 

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