Thermochemistry of 2-Aminopyridine (C5H6N2)(s)

The molar enthalpies of solution of 2-aminopyridine at various molalities were measured at T = 298.15 K in double-distilled water by means of an isoperibol solution-reaction calorimeter. According to Pitzer's theory, the molar enthalpy of solution of the title compound at infinite dilution was calculated to be Delta H-sol(m)infinity = 14.34 kJ . mol(-1), and Pitzer's ion interaction parameters beta((0)L)(MX), beta((1)L)(MX), and C-MX(phi L) were obtained. Values of the relative apparent molar enthalpies (L-phi) and relative partial molar enthalpies of the compound ((L) over bar (2)) were derived from the experimental enthalpies of solution of the compound. The standard molar enthalpy of formation of the cation C5H7N2+ in aqueous solution was calculated to be Delta H-f(m)o (C5H7N2+, aq) = -(2.096 +/- 0.801) kJ . mol(-1).