Enthalpies of Reaction of Tris(hydroxymethyl)aminomethane in HCl(aq) and in NaOH(aq).

Abstract

The enthalpy of reaction of tris(hydroxymethyl)aminomethane, NBS Standard Reference Material 724a, measured in an adiabatic solution calorimeter at 298.15 K in 0.1 N HCl solution is -245.76 ±0.26 J · g-1, and in 0.0500 N NaOH solution is 141.80 ± 0.19 J · g-1. The conditions applicable and the factors included in the overall uncertainties are discussed in detail. For the reaction in 0.1 N HCl in the range, 293 to 303 K, ΔCp = 1.435 ± 0.023 J · g-1 · K-1, and in 0.0500 N NaOH in the range, 295 to 303 K, ΔCp = 1.025 ± 0.025 J · g-1 · K-1. Possible sources of error in measurements of the reactions are discussed. A summary of other enthalpy measurements of the reaction in 0.1 N HCl is given.