where K1 and K2 represent the equilibrium constants at reference and target temperatures (T1 and T2), respectively, ΔH1 is the enthalpy change at the reference temperature (-8.0, 3.6 and 16.0 kJ/mol for pKa1, pKa2 and pKa3, respectively), ΔCp denotes the change in heat capacity at constant pressure (-141, -230 and -242 J/(mol . K) for pKa1, pKa2 and pKa3, respectively), and R is the universal gas constant (8.314 J/(mol . K). The calculations show that lowering the temperature impacts theoretical pKa in solution; at T = 0°C, pKa2 and pKa3 values slightly increase while pKa1 slightly decreases.