Trouton's Rule

[AlyssaPeckham1A]

Could someone explain how to apply Trouton's rule when solving for the standard enthalpy of vaporization?

[K Stefanescu 2I]

Trouton's rule states that the standard entropy of many liquids is approximately 85 J/Kmol. So, to use it to determine, for example, the enthalpy of a substance, we could do the following:
If liquid bromine evaporates at 59*C, what is its standard enthalpy of vaporization?
Using dS=dH/T, rewrite to solve for dH= dS(T)= 85 (59+273.15)= 28233= 28 kJ/mol

(This example was taken directly out of the book. An exam question would likely be a bit more complex, perhaps requiring us to solve for H before applying this method. The use of Trouton's rule remains the same in this case.)