Vapor Pressure vs Temperature

Known as the Clapeyron equation, this is an exacl thermodynamic relation, providing a vital connection between the properties of the liquid and vapor phases. Its use presupposes knowledge of a suitable vapor pressure vs. temperature relation. Empirical in nature, such relations are approximated by the equation... 

The graph of total vapor pressure vs temperature is drawn below ... 

Fig. 139 Vapor pressure vs. temperature curve for isobutyl alcohol. Clausius Clapyron...

The interactive Vapor Pressure vs. Temperature activity (eChapter 105) compares the number of molecules having a given kinetic energy at two different temperatures. 

When Eq. (4.11) is applied to the vaporization of a pure liquid, dPM/ dT is the slope of the vapor pressure-vs.-temperature curve at the temperature of interest, AV is the diffeVence between molar volumes of saturated vapor and saturated liquid, and AH is the latent heat of vaporization. Thus values of AH may be calculated from vapor-pressure and volumetric data. 

Vapor pressure vs. temperature data are presented graphically for the rare earths by Beavis (7). 

FIG. 1 Vapor pressure vs. temperature curves for water and benzene. 

The liquid solvent added to a pharmaceutical material generally exists in a variety of states. Some will condense or be pulled by capillary forces into macroscopic pores and fissures or into the interstitial spaces between particles. A state of local equilibrium can be assumed to exist at the interface between the liquid and vapor phases of solvent so situated. As a result, the temperature and vapor pressure exerted by the condensed solvent will not be independent of one another. Fig. 4 shows the equilibrium vapor pressure vs. temperature relationship for a number of common solvents. Heats of vaporization are shown parenthetically. Among common solvents, acetone has the highest vapor pressure and water the lowest. Water requires three-five times the energy of the common organic solvents to vaporize. 

Figure 3-4. A plot of vapor pressure vs. temperature for water and ethanol.

Figure 2. Vapor pressure vs. temperature benzene-n-heptane-methylcyclohexane...

Figure 1. Vapor pressure vs. temperature curves of important components of orange essential oil (0 0) a-pinene, ( - ) d-limonene, ( A - A ) myrcene, ( o - o ) linalool, ( - ) a-terpineol, ( - ) decanal, ( A - A ) a-citral (Data from (38)).

Vapor Pressure vs. Temperature for Aqueous Solutions of Monoethanolamine... 

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