Eucken’s equation

Approximate values for the thermal conductivity of pure gases, up to moderate pressures, can be estimated from values of the gas viscosity, using Eucken s equation, Eucken (1911) ... 

For Eucken s atomic heat of solid argon the equation C, =/(y) + o °0034T ... 

He said that the vap. press, curve of liquid nitric oxide is somewhat anomalous, and this is attributed to polymerization of the molecules at low temp. The fact that the vapour density at atmospheric press, is quite normal at these temp, indicates, however, that the dissociation of the polymerized mols. is practically complete at this pressure. The high density of the liquid at its b.p., 1 -269, is cited as evidence in support of the view that the liquid mols. are associated. W. Nernst s value for the chemical constant is about 3-7 J. R. Partington s, 1-263 F. A. Hen-glein, and A. Langen, 0-92 and A. Eucken and co-workers gave 0-03 for the integration constant of the thermodynamic vap. press, equation and A. Eucken and F. Fried, 0-95 for the constant in the equilibrium equation for 2NO=N2-j-02. 

For crystals the lower limit of the integral is zero from the considerations just outlined. Equation (57) may be integrated if a relation between Cp and T is known. The available analytical relations are. however, complicated and of limited validity. Fortunately values of S may be obtained from measurements of heat capacity at different temperatures by graphical methods, A convenient method is one proposed by Lewis and Gibson17 which consists in plotting values of Cp/T against T and determining the area of the enclosed plot. Such a plot is shown in Fig. 7 for tine estimation of the entropy of metallic silver, from the work of Eucken, Clusius and Woitinek.18 Below the lowest... 

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