The complex dielectric permittivity of aqueous sodium chloride solutions has been determined in the frequency range 0.2 ≤ ν(GHz) ≤ 20 with a commercial dielectric measurement system based on a vector network analyzer. NaCl solutions 0.1 ≤ m (mol kg-1) ≤ 5 (mass fraction 0.005 ≤ w ≤ 0.23) were investigated at 5, 20, 25, and 35 °C. An improved calibration procedure of the dielectric measurement system for conducting samples was developed. The complex permittivity spectra have been represented by a Cole−Cole relaxation time distribution. Where possible, the obtained fitting parameters, static permittivity ε and relaxation time τ, and distribution parameter α, are compared with literature data to assess the performance of the instrument, which was found to be comparable to that of time domain and waveguide systems. Effective solvation numbers were deduced from the effect of NaCl concentration on ε. The data suggest that in addition to the irrotational bonding of water molecules by Na+ ions, kinetic depolarization under slip boundary conditions determines the solution permittivity. A three-state model is proposed to describe the concentration dependence of τ.

The complex dielectric permittivity of aqueous sodium sulfate solutions (0.025 e c/mol dm -3 e 1.6) has been determined in the frequency range 0.2 e ν/GHz e 20 with a commercial dielectric measurement system based on a vector network analyzer. The spectra were supplemented with interpolated literature data at 12 e ν/GHz e 89. To fit the complex permittivity spectra, a superposition of three Debye relaxation processes was necessary. The slow and intermediate dispersion steps are assigned to the tumbling motion of doubly solvent-separated (2SIP) and solvent-shared (SSIP) NaSO 4ion pairs, respectively. The fast process, of amplitude S 3 , is due to the collective relaxation of the solvent. Effective solvation numbers were deduced from the effect of Na 2 SO 4 concentration on S 3 . From the ion-pair dispersion amplitudes, S 1 and S 2 , the concentrations c 2SIP and c SSIP , and thus the overall stoichiometric stability constant, β NaSO 4 -, were determined.

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The complex dielectric permittivity of aqueous NaOH (c e 2 M) and of dilute (e0.6 M) NaAl(OH) 4 and NaB(OH) 4 solutions in NaOH ([Na] ) 1 M) at 25 °C has been determined in the frequency range 0.2 e ν/GHz e 20. All spectra could be represented by a single Cole-Cole relaxation time distribution attributed to the cooperative relaxation of the solvent. The concentration dependence of the effective hydration number of OHhas been determined. For aluminate and borate solutions the deduced parameters: effective conductivity κ e , static permittivity , relaxation time τ, and distribution parameter R suggest a 1:1 replacement of hydroxide by aluminate and borate, accompanied by a release of bound water. The lack of an ion-pair relaxation process despite notable ion association suggests that rapid proton exchange is important not only for the dynamics of OHbut also for Al(OH) 4and B(OH) 4 -.

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