A Calorimetric Determination of the Enthalpy of Ionization of Water and the Enthalpy of Protonation of THAM at 5, 20, 25, 35, and 50 Degrees C.

Hydrolysis of neptunium(V) at variable temperatures (10–85°C)

“…The performance of the calorimeter has been tested by measuring the enthalpy of protonation of tris(hydroxymethyl)-aminomethane (THAM). The results (in kJ mol Ϫ1 ) are Ϫ47.7 Ϯ 0.3 (25°C), Ϫ46.8 Ϯ 0.2 (40°C), Ϫ45.8 Ϯ 0.5 (55°C), Ϫ45.2 Ϯ 0.5 (70°C) and Ϫ43.1 Ϯ 0.8 (80°C), compared well with the values in the literature: Ϫ46.0 Ϯ 0.3 at 45°C and Ϫ46.2 Ϯ 0.3 at 70°C (Smith et al, 1992), Ϫ46.81 Ϯ 0.02 at 35°C and Ϫ46.0 Ϯ 0.02 at 50°C (Grenthe et al, 1970). In the titrations of Np(V) hydrolysis, the initial cell solutions (ϳ0.90 cm 3 at 25°C) usually contained 0.28 -0.57 mmol dm Ϫ3 NpO 2 Cl and ϳ 0 -0.5 mmol dm Ϫ3 HCl.…”

Enthalpies of proton adsorption onto Bacillus licheniformis at 25, 37, 50, and 75°C

“…H 2 O that occurs with the addition of acid. The enthalpy of this reaction at 50°C for a similar experimental system (0.11 M ionic strength with NaCl electrolyte) was À50.65 kJ/mol and was estimated to be À56.20 kJ/mol at 25°C, and À44.52 at 75°C by interpolation of heats of NaOH neutralization reported for HCl solutions with ionic strength of 0.11 M (Grenthe et al, 1970). In this work, the correction for the heat of hydroxide neutralization was necessary only for the high pH experiments.…”

“…The heat flow response by the calorimeter was calibrated by electrical heating, a procedure verified by measuring the heat of protonation of trishydroxymethylaminomethane (TRIS/THAM) at 25°C (Grenthe et al, 1970). Both cells were filled with identical 80 g/L (wet mass) bacterial suspensions in 0.1 M NaClO 4 and placed in the calorimeter.…”

Enthalpies and entropies of proton and cadmium adsorption onto Bacillus subtilis bacterial cells from calorimetric measurements

“…The calorimeter's response to the heat flow was calibrated by electrical heating, a procedure that we have previously verified by checking the reported protonation heat of trishydroxymethylaminomethane (TRIS/THAM) at 25°C (Grenthe et al, 1970). Initially, both cells were filled with identical solutions (in this case, a bacterial suspension containing 0.1 M NaClO 4 to buffer ionic strength) and placed in the calorimeter bath.…”