Acidic dissociation constant and related thermodynamic quantities for diethanolammonium ion in water from 0 to 50 °C

The dissociation constants of diethanolamine (2 :2' -dihydroxydiethylamine) and its conjugate acid were determined by electromotive force measurements of the cell in the temperature range 0 to 50 °e.The acidic dissociation constant (K bh) of the diethanolammonium ion is given by 1830.15 -log K b h = -T --+ 4.0302 -0.0043261 T, where T, the temperature on the Kelvin scale, lies between 273.15 and 323.15°.From this equation were calculated flG o, the change in free energy; flIIo, the change in heat content; flSo , the change in entropy; and flC: , the change in heat capacity that accompany the dissoci::1tion of 1 mole of diethanolammonium ion in the standard state .At 25 °e, -log K bh = 8.883 ; fl Go = 50,682 joule mole-I; flf£o = 42,400 joule mole-I; flS o= -27.8 joule deg-1mole-l ; and flC;'= 49 joule d eg-1mole-l .