Ionic liquids ideal Walden plot

Figure 1.3 Walden plot Pipper and modified Walden plot Howerl for a variety of ionic liquids. For the upper curve. tA is the ideal Walden plot line for KCl. IBl is the Walden plat taking account of ionic size, and ICl is the Walden plot if the conductivity...

Schreiner et al. recendy published a critique of the use of the Walden rule with ionic liquids [17]. They suggested that use of the enpirical approach from Stokes, Equation 1.7. explains the observed deviations from the so-called ideal Walden plot, since each salt will have a different value of C and a ... 

Figure 2.10 Dependence of the cohesion of salts of weakly polarizable cations and anions, assessed by Tg value, on the ambient temperature molar volume hence on interionic spacing [(r -i- r) V ]. A broad minimum in the ionic liquid cohesive energy is seen at a molar volume of 250 crrPnmr, which corresponds to an interionic separation of about 0.6nm, assuming face-centered cubic pacidng of anions about cations. The lowest Tg in the plot should probably be excluded from consideration because of the non-ideal Walden behavior for this IL (MOMNMgE BF ) [15]). The line through the points is a guide to the eye. The data for open triangles are from Sun, Forsyth, and MacFatlane [42].

As has been observed previously, the vast majority of the ionic liquids fall slightly below the ideal 1 1 Walden line [23,47,51,82]. A linear regression was performed on the data giving a slope of 1.11, an intercept of-0.235, and Sf = 0.958. The fit of the data to the linear relationship is surprisingly good when one considers the wide variety of ionic liquids and the unknown errors in the literature data. The linear behavior in the Walden Plot clearly demonstrates that ionic liquid conductivity and its viscosity are strongly coupled. Furthermore, it shows that aU the ionic liquids exhibit normal Walden type conductivity where the conductivity arises from the movement of mobile charge carriers [23,47]. 

Fig. 3.6-4 The Walden plot of the molar conductivity and viscosity data in Tables 3.5-4—3.5-8. ( ) haloaluminate ionic liquids, (A) non-haloaluminate imidazolium ionic liquids, (V) ammonium ionic liquids, (o) other ionic liquids. The line represents the ideal 1 1 Walden...

Schreiner C, Zugmann S, Hartl R, Gores HJ (2010) Fractional Walden rule for ionic liquids examples from recent measurements and a critique of the so-called Ideal KQ line for the Walden plot. J Chem Eng Data 55 1784-1788... 

Fig. 3.4 Walden plots for proton conductors. The ideal line is for 0.1 mol KCl. Data for sulfuric acid, phosphoric acid, and the pseudo-ionic liquid of methylimidazole and acetic acid were taken from...

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