Thermodynamic Parameters of Coupled Chemical Reactions from Temperature Jump Relaxation Amplitudes

Article abstract of DOI:10.1007/BF00652779

Equations describing the temperature jump amplitudes associated with a system of two coupled reactions (TRIS - phenol red) as well as the ternary system (Mg(2+) - iminodiacetic acid - phenol red) are presented.The thermodynamic parameters calculated from experimentally measured temperature perturbation amplitudes using a multiparametric curve fitting procedure are found to be in good agreement with those determined from pH- and constant rate thermometric titrations.For phenol red, pK_I = 7.55, ΔH_I = 3.45 kcal, and for Mg(2+) iminodiacetic acid , logK_M = 2.84, ΔH_M = 3.25 kcal, were obtained.It is shown that this method can be used to determine accurate thermodynamic enthalpy changes over a narrow temperature interval of less than 1.0 deg C from a single experiment requiring about 50 μl of sample solution.