Othmer equation

Othmer Equation The Othmer equation relates r(T) to the critical temperature, Tc, and a reference point given by crref at Tref  

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Yaws et al. (10] have compiled and evaluated the parameters needed in the Othmer equation for over 600 compounds. An example is shown in Figure 5.4.1, where the surface tension of acetic anhydride at 16.5°C has been estimated. 

Results from the data compilation of Yaws and co-workers (44,55) were selected. Using data from the literature, surface tension over the full liquid range was achieved by the modified Othmer equation ... 

For the DIFPR project (5), surface tension was correlated by a slightly different Othmer equation ... 

The data compilation Yaws and co-workers (31,44,55) was selected for surface tension for temperatures from melting point to critical point except for epichlorohydrin (5). Using data from the literature, correlation for surface tension as a function of temperature over the frill liquid range was achieved by the modified Othmer equation, Equation (l-4a). Accuracy is good with errors being about 1-10% or less in most cases. 

Thus, and as previously described for viscosity, the surface tension of the DESs decreases as the ratio of the HBA increases, supporting again tire fact that addition of the salt (i.e., ChCl or ZnCl2) disrupts the extensive hydrogen bond network of the HBD (i.e., polyols, urea, carboxylic acids). Also, and as aforementioned for viscosity, the surface tension showed a linear correlation with temperature. Shahbaz et a/." used the Othmer equation to predict the surface tension of different DESs with a mean percentage error of only 2.57%. The Othmer equation is as follows ... 

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