Trouton’s law

Example 1. The normal boiling point of nonane is 150.8°C and its vapor pressure is 400 mm Hg at 128.2°C. What is the Avap7/° of nonane Compare Avap.S with the Trouton s law value, 85 J/Kmol. 

Show that in the ideal solution limit, for a group of solvents obeying Trouton s law, the fractional change of boiling point produced by a given mole fraction of solute is the same for all the solvents. 

So, the molar heat of vaporisation of a liquid divided by its boiling point on absolute scale, i.e., Le/Tb is constant and is approximately equal to 23, provided the latent heat is expressed in calories. This fact was first observed by Pictet (1876) and rediscovered by Ramsay (1877) and Trouton (1884) and is commonly known as Trouton s law. 

The solid and liquid phase is known as a condensed phase. The condensed phase results due to intermolecular forces. An approximate relationship between the strength of intermolecular forces and the boiling points is provided by Trouton s Law. According to it the value of AS°yap is around 90 JK-1 mol-1... 

When calculating the parameters for the design of a distillation unit, the assumption is made that Trouton s law applies. The energy necessary for heating up and evaporation can be transferred by... 

The expression for the vapor pressure p, in atm., of any substance to which Trouton s law is applicable thus becomes... 

From the results of the preceding exercise determine (approximately) the constant C in equation (27.16), and see how close the result is to that expected from Trouton s law. Using the values of AHv and C just obtained estimate the normal boiling point of carbon tetrachloride. (The actual value is 76.8° C.)... 

Wilson, G.M., Interpretation of Trouton s law in relation to equation of state properties. Equations of State, Theories and Applications, American Chemical Society Symposium Series 300, Washington, D.C, 1986. 

An empirical law known as Trouton s Law says that the entropy of vaporization is almost constant, about 20.3 cal mol K . Water has an anomalously large entropy of vaporization of about 26 cal mol Table 1.6 shows the entropy of vaporization divided by the gas constant R for different liquids. Note that the entropy of vaporization of ethanol is as large as that of water. 

When the heat of vaporisation is expressed in kJ/kg and Tboiimg in Kelvin, the constant is 96. Trouton s law... 

For polymeric liquids, Trouton s law holds only in the limit of vanishingly low deformation rates,(12) j e.,... 

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