Othmer plot

By use of Othmer plots of reference substances, large tables of thermodynamic data can be expressed as simple correlations which are extremely accurate and easy to use. The real power of these correlations is the abiUty to interpolate and extrapolate the correlations beyond the experimental values with considerable accuracy. Mathematically stated... 

An alternative way to extrapolate vapor pressure data would be to use the Othmer plot as explained in Sec. 4.4, or to fit a vapor pressure equation, p =f(T), firom experimental data. 

To indicate how to apply the Othmer plot to estimate the heat of vaporization of compound A, we apply the Clapeyron equation to each substance and take the... 

Figure 4,11 Othmer plot and vapor-pressure curves.

The Othmer plot works well because the errors inherent in the assumptions made in deriving Eq. (4.20) cancel out to a considerable extent. At very high pressures the Othmer plot is not too effective. Incidentally, this type of plot has been applied to estimate a wide variety of thermodynamic and transport relations, such as equilibrium constants, diffusion coefficients, solubility relations, ionization and dissociation constants, and so on, with considerable success. 

Repeat the calculation for the heat of vaporization of isobutyric acid at 200°C using an Othmer plot. 

Make an Othmer plot for refrigerant 12, and calculate the latent heat of vaporization at 100°F compare this value with the one calculated from the following experimental data ... 

Make an Othmer plot to determine the heat of vaporization of at... 

Similarly as for citric acid, Martinez de la Cuesta et al. [154] reported boiling points for NajCit and KjCit by using the Diihring and Othmer plots. These plots give approximately values of boiling points and vapour pressures at Tj p(w) using the corresponding values for water in the form... 

OTHMER, D.F. Ind. Eng. Chem. 32 (1940) 841. Correlating vapor pressure and latent heat date. A new plot. 

The tieline data of the system of Example 14.1 are plotted according to the groups of variables in the equations of Ishida, Hand, and Othmer and Tobias with these results ... 

Tie Line Correlations Useful correlations of ternary data may be obtained by using the methods of Hand [/. Phys. Chem., 34(9), pp. 1961-2000 (1930)] and Othmer and Tobias [Ind. Eng. Chem., 34(6y pp. 693-696 (1942)]. Hand showed that plotting the equilibrium line in terms of mass ratio units on a log-log stiJe often gave a straight line. This relationship commonly is expressed as... 

Figure 13.3-2 Modified plot of drag coefficient for spheres (from Zenz and Othmer [10].

Since this is not a rigorous analysis, the predictions may not be accurate for 6 6 and 6 6. Othmer (1975) plots some numerically... 

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