Chloromethanes chloride transfer from

The reason is that ions are much more stable in water than in the gas phase for example, the transfer of a chloride ion from the gas to water is exothermic by —85 kcal. The AH° value for the corresponding transfer of a methyl cation, CH3 is not known with certainty, but is about —80 kcal. These ionic solvation energies are clearly large. In contrast, the AH° for solution of methyl chloride in water is small (about 1 kcal). We can use these data to calculate the heat of ionic dissociation of chloromethane in water ... 

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