Vapour-pressure Equations

In the discussion which follows, symbols have the following meanings p vapour pressure 

Chebyshev polynomial coefficients in equation (26) coefficients in equation (29) 

In the section of his treatise dealing with equations relating vapour pressure to temperature, Partington S listed more than fifty formulae which have been used since Dalton first suggested that the vapour pressure was proportional to some power of the temperature. Few of them are of more than historical interest, and today almost all are related to the simple approximate form  

Partington, An Advanced Treatise on Physical Chemistry , Longmans, London, 1951, vol. 2, p. 265. 

At temperatures less than Tt = 0.75, the equation most widely used today is that due to Antoine, which the Reporter now prefers in the form 

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The analogy between (17) and the Kirchhoff vapour-pressure equation ( 88) is evident. R. T. Hardman and the author have shown that (17) enables one to calculate the solubility when the solubility parameters A, B, C have been obtained, and this... 

It is evident that the laws of dilute solution, assumed in the deduction of (17), cannot apply to solutions, or rather syrups, containing more than three times as much sugar as water. The analogy between (17), and Kirchhoff s vapour-pressure equation is therefore surprisingly extensive. 

The vapour-pressure equation (22) has been verified for brom-and iodo-naphthalene by L. Rollo(7) (1909), and for toluene, naphthalene, and benzene by J. T. Barker (1910). The latter finds that the solid and liquid states give the same chemical constant, which is in agreement with Nemst s theory. 

Gas, cells, 464, 477, 511 characteristic equation, 131, 239 constant, 133, 134 density, 133 entropy, 149 equilibrium, 324, 353, 355, 497 free energy, 151 ideal, 135, 139, 145 inert, 326 kinetic theory 515 mixtures, 263, 325 molecular weight, 157 potential, 151 temperature, 140 velocity of sound in, 146 Generalised co-ordinates, 107 Gibbs s adsorption formula, 436 criteria of equilibrium and stability, 93, 101 dissociation formula, 340, 499 Helmholtz equation, 456, 460, 476 Kono-walow rule, 384, 416 model, 240 paradox, 274 phase rule, 169, 388 theorem, 220. Graetz vapour-pressure equation, 191... 

Machines, 25, 52 Macro-differential, 39 Magnetic energy, 27 Magnus s vapour-pressure equation, 180... 

Range of a process, 114 Rankine s cycle, 113 vapour-pressure equation, 179 Raoult s freezing-point law, 299 ... 

The simulation emphasises that when reactions start to run away they do so extremely fast. In this example the rate of pressure generation is compounded by the double exponential terms in the Arrhenius and vapour pressure equations. 

The equation presented here, due to Haggenmacher (1946), is derived from the Antoine vapour pressure equation (see Section 8.11). 

Values of the coefficients AL and of the constants B and C for the 3He and 4He vapour pressure equations and the temperature range for which each equation is valid [14-16]... 

Equation (11) is an integrated form of Clausius-Clapeyron equation. If the integration is carried out indefinitely (without limits) then we can write the vapour-pressure equation (9) as,... 

Mujtaba and Macchietto (1988) and Mujtaba (1989) used two typical binary mixtures and a variety of separation specifications to demonstrate how optimal recycle policies can be obtained and to assess the validity of the degree of difficulty measure. The mixtures were 1) Benzene-Toluene 2) Butane-Pentane. For simplicity ideal equilibrium and Antoine s vapour pressure equations were used. The light component was always the first one. 

Creighton 1 proposed a formula for fluidities similar to Ramsay arid YdQng s vapour pressure equation, 8.VIII K. If R and R are the ratios of the absolute temperatures for which two liquids have the same fluidities =ljrj then ... 

Several vapour pressure equations have been used specially for water ... 

An important vapour pressure equation was proposed by Rankine, Kirch-hoff,8 and Dupr6 ... 

This is Kirchhofif s vapour pressure equation ( 19.VIIIJ), which applies empirically over a wide range of temperature (almost to the critical point) i in the form ... 

Av=vg—vi), which gives approximate results with steam. Values ofp(dTjdp) were calculated by Kirejew and related to cohesive forces, latent heats, and the van der Waals vapour pressure equation ( 22,VIIC). 

Palacios by taking account of gas imperfection by a characteristic equation, obtained a good value for the chemical constant of hydrogen (Ih2= 1-105) from the vapour pressure equation. 

Valson s law of moduli, 32, 198 van der Waals s constants, 23, 154-5 surface tension equations, 141, 151 vapour pressure equation, 267... 

The vapour pressure equations (21.21) show that in the present case... 

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