Equilibria in ethylenediamine. III. Determination of absolute pK values of acids and silver salts. Establishment of a pH and pAg scale

The dissociation constant for the reaction HCl ⇌ H⁺ + Cl^- in ethylenediamine has been determined by spectrophotometric and cryoscopic measurements. The mean value of pK_HCl, 4.01, has been used to calculate the potential of the saturated corrosive sublimate electrode (s.c.s.e.) and E°_Ag+,Ag using electrodes of the first and second kinds. E.m.f. values obtained with the hydrogen electrode in solutions of acids and in solutions of salts were used to calculate pK values of acids. Similarly, from e.m.f. values obtained using the silver electrode in silver salt solutions, the corresponding pK values were evaluated. Cryoscopic determination of the pK value for hydrobromic acid in ethylenediamine is also reported.