Using the molecular rotational motion concept to predict the volume expansion coefficients of liquids.

The rotational motion of molecules in the liquid phase has been shown to be one of the main factor that determines the liquid's thermal expansion and can be used for its calculation based on an expression for the partition function of the rotational motion of ideal gas molecules, taking into account the contribution of intermolecular interactions. This study establishes that the thermal expansion temperature coefficients are grouped in sequences depending on the functional class of compounds. The general hydrocarbon sequence breaks down into separate sequences according to their functional groups, such as saturated or aromatic hydrocarbons. Thus, it is shown a correlation between the thermal expansion of liquids with an average size of molecules, at temperatures well below the boiling point, and the entropy of the rotational motion which is a function of the moments of inertia of molecules and temperature. [ABSTRACT FROM AUTHOR]