Results and Discussion Illustration of the HSAB Principle

Acid diiodine Base iodocyclohexane Solvent cyclohexane Density (25 0 = 0.7735 Path length = 1 cm Wavelength (nm) = 470.15 nm Stock solution of acid Acid weight = 0.2218 Solution weight = 77.5447 Molar mass = 253.81 g mof Molar mass = 210.06 g mol Molar mass = 84.16 g mol dd/dt = 0.00101 Temperature = 16.1 °C Stock solution of base Base weight = 4.7773 Solution weight = 27.3742  

All four sequences obey the Hard and Soft Acid and Base (HSAB) principle. Indeed, diiodine is a soft Lewis acid, 4-fluorophenol a hard Lewis acid, and the softness of the electron donor atom increases (that is hardness decreases) in descending group 17 of the periodic table (see Table 1.16 in Chapter 1). 

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