Which of the following reactions has the greatest entropy change?
addition, elimination, substitution and rearrangement. (why?)

Question

anonymous · Answer

Elimination.  That creates two molecules where there used to be one, and the increase in translational entropy dwarfs any change to internal entropy that comes about because of re-arrangements within each molecule.  In addition you make 2 molecules from 1, in substitution you get 2 from 2, and in rearrangement you get 1 from 1 -- so in all cases there is no increase in the number of molecules.

anonymous · Answer

Sorry, I meant, in addition you make 1 molecule from 2.