The enthalpy of solution of SRM 1655 (KCl) in H2O

Abstract

The value for the enthalpy of solution of SRM 1655 (KCl), Δ<i>H</i>°(500 H₂O, 298.15 K) = (235.86±0.23)J·g^-1 or (17.584±0.017)kJ·mol^-1, was obtained from measurements in an adiabatic calorimeter, and confirmed by measurements in an isoperibol calorimeter. Enthalpy of solution measurements are reported in the temperature range 296 K to 358 K, at molalities between 0.005 and 0.18 mol-kg^-1, for various ranges of particle size up to 1000 <i>μ</i>m, and in CO₂- saturated solutions. Observations were also made relative to the hygroscopicity, removal of occluded H₂O, and homogeneity of SRM 1655. Between 296 K and 303 K, Δ<i>C</i> _<i>p</i> =-(2.076±0.087) J·g^-1·K^-1or -(154.8±6.4) J·mol^-1·K^-1 for the reaction of SRM 1655 in 500 H₂O.