Symmetrical molar conductivity

Figure 5. (a) The ( A, SO,) anion symmetric streching mode of polypropylene glycol)- LiCF,SO, for 0 M ratios of 2000 1 and 6 1. Solid symbols represent experimental data after subtraction of the spectrum corre-ponding to the pure polymer. Solid curves represent a three-component fit. Broken curves represent the individual fitted components, (b) Relative Raman intensities of the fitted profiles for the ( Aj, SO,) anion mode for this system, plotted against square root of the salt concentration, solvated ions ion pairs , triple ions, (c) The molar conductivity of the same system at 293 K. Adapted from A. Ferry, P. Jacobsson, L. M. Torell, Electrnchim. Acta 1995, 40, 2369 and F. M. Gray, Solid State Ionics 1990, 40/41, 637. 

Scheme 1). In addition to the determination of molar conductivity, magnetic moment, and IR spectra, the complex was characterized by X-ray structural analysis (4). This indicates that the cationic complex with neutral H2dapsox is symmetrically coordinated as a pentadentate ligand. Co(II) occurs in a PBP environment with water and methanol molecules in apical positions (Fig. 1). Although the side chains are symmetrically coordinated, Co-O(eq) bond lengths differ significantly. 

Molar Conductivity of Dilute Solutions of Symmetrical Strong Electrolytes... 

Molar Conductivity and Association Constants of Symmetrical Weak Electrolytes... 

The molar conductivity experimentally obtained, A, is plotted as a function of square root of the concentration of tetraaikylammonium picrate (Q pic ), Vc. The results of tetrahexylammonium (TAA6 ), trioctylmethylammonium (TOMA ) and cetyltrimethylam-monium (CTMA ) ions are depicted in Fig. 1. Similar results were obtained for other symmetric tetraaikylammonium ions (TAAn (C H2 j)4N, n = 1-8). 

Following the concept underlying the MSA-MAL conductivity equation [3, 32, 33] and by taking into account that the total concentration of electrically conducting particles is molar conductivity in the AMSA for symmetrical electrolytes [13]. The possibility of such modification of the AMSA theory is quite promising for the description and interpretation of thermodynamic and transport properties of electrolyte solutions in a weakly polar solvent. 

Each ion present in the solution thus makes a contribution to the total conductivity of the solution. Likewise the total molar conductivity of the solution will be made up of contributions from the cations and anions present in the solution. But care must be taken here the relation is not a simple additive one, but is one which reflects the stoichiometric formula of the electrolyte, and, in particular, whether the electrolyte is symmetrical or unsymmetrical. 

Shortly after Debye and Hiickel had presented their momentous work on the free energy of electrolyte solutions, Onsager derived theoretically, the empirical equation proposed by Kohlrausch to represent the molar conductance of an electrolyte solution. For solutions of a single symmetrical electrolyte this equation is given by... 

AJ is the limiting molar conductance at infinitesimal ionic strength, and the relaxation and electrophoretic parameters a and jS, respectively, are defined in eqn. 5.2.3. From eqns. 5.8.3 and 5.10.1 the transference number of a completely dissociated symmetrical electrolyte is given by... 

Hu and Chao [7] performed two-dimensional numerical simulation on the performance of an electroosmotic pump for planar channels. The model is able to handle the case with the dimensions comparable to the EDL thickness. Also no Debye-Huckle approximation and symmetric conditions are required. But the results show considerable deviation from the experimentally measured ones. Yao and Santiago [8] provided useful review on the historical background of the development of EO pumps. They considered different molar conductivities for cations (A+) and anions (A ) in calculating the electric current caused by electromigration. They predicted that A+ is almost twice A for sodium ions. 

Relative Raman intensity of the symmetrical stretch in the anion (Ai, SO3) mode, and molar conductivity at 30°C with changing concentration of the polypropylene glycol (PPG)-LiCF3 03 system with ions (O), ion pairs ( ), and triple ions ( ). (Adapted from Ferry, A. et al., Electrochim. 

The equation for the molar ionic conductivity for a symmetrical electrolyte is ... 

Kreuer et al. [66] doped sulfonated poly(ether ether ketone) (sPEEK) by immersing it into liquid pyrazole and imidazole. A base doping level of 2.3-10, defined as the molar ratio of [C3N2H4]/[-S03H], could be achieved. The intercalation of imidazole and pyrazole into polymers with Brpnsted acid sites is shown to enhance the protonic conductivity. Of the two basic solvents of protons, pyrazole has a lower tendency for the molecular association by hydrogen bonding and therefore a lower proton conductivity, as compared with imidazole. Fu et al. [81, 82] studied acid-base blends based on 2-aminobenzimidazole and sPEEK. They proposed that benzimidazole is protonated by the sulfonic acid, as evidenced by the symmetric stretching of the S-O bonds in FTIR spectra. 

---