On a Relation existing Between the Latent Heats, Specific Heats, and Relative Volumes of Volatile Bodies

Trouton and T-H-E rule

“…Remembered also for the Trouton-Noble experiment, Trouton himself attached little importance to his rule, which he discovered while still an undergraduate "as the result of an afternoon spent playing with numbers." This statement of a memorialist (1) is probably too extreme, for Trouton published two closely related papers (2) in only the second of which (a year after the first) do we find Trouton's rule as such. Let X symbolize the latent heat of vaporization (in cal/g), and M the molecular weight of the vapor (in g/mole).…”

“…The potency of the structural factor thus appears well attested. 2 Rather than pursue nuances of the three factors that may evoke upward displacements of ASh, we turn at once to two molecular characteristics conspicuously inactive in perturbing the value of ASh-As demonstrated repeatedly (13)(14)(15) for the aliphatic hydrocarbons, when other things are equal even many-fold changes in molecular weight fail to perturb AS^. Beyond molecular weight, the liquid's molecular volume (u) isjhe second parameter supposed to have little bearing on ASh.…”

Modified Trouton’s Rule for the Estimation, Correlation, and Evaluation of Pure-Component Vapor Pressure

“…Frederick Trouton published his observations on the relationship between the enthalpy of vaporization and the normal boiling point in two short papers while he was an undergraduate student, and about 20 years old. , He illustrated his finding by evaluating data for just 24 compounds, and stated that the “quantities of heat necessary to evaporate at constant pressure quantities of different liquids taken in the ratio of their molecular weights, it is found that the amount of heat required by any body is approximately proportional to its absolute temperature at the point of ebullition.” Wisniak has written an informative account of the many scientific contributions of Trouton. In modern terms, Trouton’s Rule may be written as where, Δ H VL ( T b ) is the enthalpy of vaporization at the normal boiling temperature ( T b ).…”

“…The Gibbs–Helmholtz equation provides a similar relationship between the temperature derivative of the saturated fugacity and the liquid enthalpy departure . Trouton’s Rule , is an empirical and classical observation that relates the enthalpy of vaporization of fluids to the temperature of vapor–liquid phase change. In this paper, we combine the insights from the Clausius–Clapeyron equation, the Gibbs–Helmholtz equation, and Trouton’s Rule to develop a practical vapor-pressure correlation procedure that has a small number of parameters, and demonstrate its utility.…”

Comment on “Critical Properties, Normal Boiling Temperatures, and Acentric Factors of Fifty Ionic Liquids”

“…We now estimate the T b values from the experimental ∆ vap H 298 values of JL for comparison with the T b (VR) values. Trouton's rule [7][8][9] relates the normal boiling point at a pressure of 1 atm to the enthalpy of vaporization at the normal boiling point (∆ vap H Tb ) and Trouton's constant (∼85 J K -1 ) mol -1 .…”