Attaching a methyl group to various hydrocarbons

The term reaction is used here to describe the process of bringing a methane molecule from infinity to a final position next to a hydrocarbon molecule denoted RH then the pair of molecules is replaced by a single hydrocarbon denoted by R-CH3. 

This is the indirect work in bringing a methane molecule from infinite separation from RH to the final configuration similar to an existing molecule R-CH3. This process is schematically shown in Fig. 4.15. As in the previous subsection, on the right-hand side of (4.4.35), we have measurable quantities. Note that in every case in which internal rotations are involved, one must interpret the appropriate solvation Gibbs or Helmholtz energy as an average over all the conformations of the molecule. 

A different kind of information may be obtained by fixing n and examining the effects of different groups P on the solvent as they are revealed in the values of the quantity 8A. 

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