Equilibrium acidities in DMSO for benzoic acid, the enol of 1,3-cyclohexadione, and tropolone have been measured, and the BDEs for their O-H bonds have been estimated by combining the PKHA data with electrochemical data. The acidity data are not in accord with the theory that the polarity of the carbonyl group is the dominant factor in making the CO2H function acidic. Equilibrium acidities in DMSO for the alpha-C-H bonds in nine nitroalkanes have been measured and the BDEs of their acidic C-H bonds have been estimated in a similar fashion. The radical stabilization energy (RSE) of the NO2CH2* radical is estimated to be 7.6 kcal/mol, relative to the CH3* radical, based on the relative BDEs of the H-CH2NO2 and H-CH3 bonds. The finding of sizable RSEs for radicals of the type GCH(2)*, where G is an electron-withdrawing group, such as NO2, CN, SO(2)R, or O double bond CR, suggests that they behave as pi radicals capable of delocalization of the odd electron to heteroatoms, whereas ESR data indicate that they are essentially sigma radicals with electron density concentrated primarily on carbon.