pKa values
Values are for water at 25 °C. Those far outside the water range (below about −2 or above about 16: HI, HCl, NH₃, alkanes) cannot be measured in water directly and are extrapolated from other solvents, so they are approximate and differ between textbooks. Water is listed as 15.7 (the value used in most organic texts, from Kw/55.5 M); with standard thermodynamic conventions it is 14.0, which shifts hydroxide comparisons by 1.7 units but not the direction. Sources: Evans pKa table (D. A. Evans & D. H. Ripin, Harvard); F. G. Bordwell, Acc. Chem. Res. 1988, 21, 456; CRC Handbook of Chemistry and Physics.
Calculations and maps
K = 10ΔpKa and ΔG° = −RT ln K = −5.71 kJ/mol × ΔpKa at 298 K. “Converted” assumes equal starting amounts of acid and base, so x = √K/(1 + √K). Solvent effects (leveling, ion pairing) are noted but not modelled. The coloured maps are schematic electrostatic-potential pictures: the colour shows how concentrated the negative charge is, from its resonance share, the atom’s ability to hold charge, and its size. They are drawn to show trends, not computed from quantum chemistry.