Hydrocarbons, liquid solution into water, temperature

It appears that there are two temperatures of a universal nature that describe the thermodynamic properties for the dissolution of liquid hydrocarbons into water. The first of these, 7h is the temperature at which the heat of solution is zero and has a value of approximately 20°C for a variety of liquids. The second universal temperature is Ts, where the standard-state entropy change is zero and, as noted, Ts is about 140°C. The standard-state free energy change can be expressed in terms of these two temperatures, requiring knowledge only of the heat capacity change for an individual substance... 

Sutton and Calder (9) have also measured the solubilities of several alkylbenzenes in distilled water and in seawater by a method based on GC. Saturated solutions were prepared by equilibrating water with aromatic vapor in an all-glass apparatus consisting of a 1-L Erlenmeyer flask with an insert tube. The insert tube was used to store the compound. It was capped with a ground-glass stopper. The liquid hydrocarbon did not come into contact with the water except through a perforation in the insert, which allowed hydrocarbon vapors to enter the headspace above the water in the flask. The flask was placed in a constant-temperature shaking bath controlled at 25.0 dt 0.1°C. The water was equilibrated for 48 hr prior to analysis. The solubilities were determined by solvent extraction of the saturated solutions with subsequent analyses of the extracts by GC. 

Hydrophobic forces represent the tendency of water to repel nonpolar solutes, such as oils and hydrocarbons, with formation of segregated phases. The phenomenon arises from the peculiar structure of liquid water, which consists of a highly dynamic network of polar molecules tightly interconnected by a tridimensional net of H-bonds (only 20% of which are broken at room temperature with respect to solid ice). Polar molecules which are good H-bond donors and acceptors, for example methanol, become easily inserted into this network and then dissolve in water. Conversely, pure hydrocarbons which cannot... 

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