Kinetics and thermodynamics of chemical reactions in aqueous solutions
The kinetics of reaction and solvation properties of binary aqueous mixtures are discussed from different theoretical standpoints. Kinetic data are reported for reactions involving several Iron (II) complex cations in binary aqueous mixtures. The Savage-Wood Additivity Group Scheme (SWAG) is applied to kinetic data for the aquation of [Fe (5-nitro-1, 10-phenanthroline) 3]2+ in binary aqueous mixtures. Limitations of the theory are examined. The theory works well for reactions in alcohol-water and some carboxylic acid-water mixtures but not for reactions in urea-water and cyclic ether-water mixtures. The conclusion is reached that this theory can only be applied to relatively simple solutions. Otherwise, the assumptions made in the theory are not valid. Attention is then turned to the Kirkwood-Buff theory which can be applied to reactions in mixtures containing significant amounts of the cosolvent. Few assumptions are made in its derivation. This theory is used to probe the properties of a wide range of binary aqueous mixtures. Kinetic data describing reactions in these binary mixtures are then examined, leading to a consideration of preferential solvation. Finally, the possibility of monitoring chemical reactions under isochoric conditions is considered. A meaningful isochoric volume is defined. Kinetic and equilibrium reaction data are then analysed under these isochoric conditions.