Hydration of the potassium ion in the gas phase: enthalpies and entropies of hydration reactions

Abstract

The thermodynamic constants AH0,-,,,, AGO,-,,,, and AS0,,-I,, for the reaction [n -1, 111: K + ( H 2 0 ) , -, + H 2 0 = K + ( H 2 0 ) , proceeding in the gas phase were measured for tz = 1 to n = 6.The equilibria were studied in a reaction chamber containing water vapor at pressures from 0.3 to 6 Torr and at temperatures from -11 to 390 O C . The potassium ions were produced by thermionic emission in a filament chamber and then were equilibrated with the water vapor in the reaction chamber. The relative ionic concentrations were detected with a mass spectrometer. The experimental AH0,,-,,, values are compared with potential energy differences for the reactions [n -I, n] based on simple electrostatic model calculations. The electrostatic calculations produce values in fair agreement with the experimental results. The ASoo,, calculated on basis of statistical mechanics and energies obtained with the electrostatic model is in very good agreement with the experimental result.

Heavy Water Reactions with Atomic Transition-Metal and Main-Group Cations: Gas Phase Room-Temperature Kinetics and Periodicities in Reactivity

“…value of ∆H°in our experiment is about 12.1 kcal mol -1 based on ∆S°) 19.4 eu, 22 which is in good agreement with the value 12.9 kcal mol -1 in Table 4. Figure 6 explores the periodic variation in the values of the measured efficiencies and the standard binding free energies observed from our equilibrium measurements (see Table 6) for the addition of D Table 5).…”

Binding energies and stabilities of potassium ion complexes with ethylene diamine and dimethoxyethane (glyme) from measurements of the complexing equilibria in the gas phase

“…The ion source used is similar to that described earlier (16) but incorporated a few modifications (5, 17), made to increase the leaktightness of the source and the temperature homogeneity of the gas in the equilibration chamber.…”

Evaluation of Different Implementations of the Thomson Liquid Drop Model: Comparison to Monovalent and Divalent Cluster Ion Experimental Data

“…55 For this model, the free energy contribution of the interaction between the dipole and cluster ion (ΔG IDI ) to the stepwise binding free energy was calculated to be (10) where E n-1 = ze/(4π∊ 0 (R n + R 1 ) 2 ), x = μ 0 E n-1 /kT, α is the polarizability of L, and μ 0 is the dipole moment of L. The free energy contribution of the ion-dipole interaction is the force between the ion and both the induced and the permanent dipoles integrated over the reaction coordinate distance for removing L from the surface of ML n z to infinite distance. The corresponding entropy (ΔS IDI ) was obtained from the differential of the eq 10 free energy with respect to temperature resulting in (11) where L(x) = [coth(x)] -x −1 . These terms are combined with eqs 8 and 9 to calculate ΔH n,n-1 values.…”