Walden s rule

From equation A2.4.38 we can, finally, deduce Walden s rule, which states that the product of the ionic mobility at infinite dilution and the viscosity of the pure solvent is a constant. In fact... 

The conductivity and viscosity of an ionic liquid is often combined into what is termed Walden s rule [Equation (3.6-4)] [54],... 

As was discussed earlier in Section 1.2.8 a complication arises in that two of these properties (solubility and vapor pressure) are dependent on whether the solute is in the liquid or solid state. Solid solutes have lower solubilities and vapor pressures than they would have if they had been liquids. The ratio of the (actual) solid to the (hypothetical supercooled) liquid solubility or vapor pressure is termed the fugacity ratio F and can be estimated from the melting point and the entropy of fusion. This correction eliminates the effect of melting point, which depends on the stability of the solid crystalline phase, which in turn is a function of molecular symmetry and other factors. For solid solutes, the correct property to plot is the calculated or extrapolated supercooled liquid solubility. This is calculated in this handbook using where possible a measured entropy of fusion, or in the absence of such data the Walden s Rule relationship suggested by Yalkowsky (1979) which implies an entropy of fusion of 56 J/mol-K or 13.5 cal/mol-K (e.u.)... 

Wagner s solution See Wagner s reagent. vag narz sa.Iu shan 1 Walden s rule phys chem A rule which states that the product of the viscosity and the equivalent ionic conductance at infinite dilution In electrolytic solutions is a constant, independent of the solvent It Is only approximately correct. wol-danz, rul ... 

If Ka > 107 mol-11, the slope of the linear relation is too large to obtain reliable A Xj (or Ka) values. In these cases, we obtain the value of A°° separately, either by use of Walden s rule or from the known values of ionic molar conductivities (A 0), and use it to obtain KA. 

Stokes Law and Walden s Rule - Role of Ultrafast Solvent Dynamics... 

Walden s rule is applicable for such ions as Bu4N+, (n-Am)4N+, (i-Am)4N+, Hex4N+, (i-Am)3BuN+, Ph4As+, BPh4 and (i-Am)4B .4) For these ions, the value of 2°° in a given solvent can be obtained from the known value in different solvents. The inaccuracy of this method is 1 or 2%. 

As mentioned in Section 7.1, if we determine the molar conductivity of an electrolyte as a function of its concentration and analyze the data, we can get the value of limiting molar conductivity A°° and quantitative information about ion association and triple-ion formation. If we determine the limiting molar conductivity of an ion (7 °) by one of the methods described in Section 7.2, we can determine the radius of the solvated ion and calculate the solvation number. It is also possible to judge the applicability of Walden s rule to the ion under study. These are the most basic applications of conductimetry in non-aqueous systems and many studies have been carried out on these problems [1-7]. 

Yalkowsky (1997) has shown, by applying Walden s Rule (and as discussed in Chapter 7 on solubility in water), that many organic compounds have entropies of fusion of approximately 56.5 J/mol K. Thus this relationship simplifies at a temperature T of 298 K to... 

For solids, it is essential to correlate Kow with the liquid solubility, not the solid solubility thus the fugacity ratio expression must be included in any correlation. This is readily done, since melting point TM(K) is usually available and Walden s Rule can be applied. Following Yalkowsky (1979), the fugacity ratio F can be estimated at 25°C (T = 298 K) as... 

For enthalpies of fusion at the melting point, one may use Walden s rule 181... 

This equation is known as Walden s rule. The constant is called the Walden product. Although the salt contents of bulk ILs are very high (about 3-7 mol L-1), the Walden plots for a variety of ILs are similar to that of a conventional diluted system [113]. This observation indicates that ILs are ionized effectively, even in the bulk. However, ILs also contain ion aggregates which do not contribute to the ionic conductivity. Recent research shows more specifically how much ILs are ionized [114]. 

Assuming that the entropy change of organic nonelectrolytes at the melting temperature is given by Walden s rule (i.e., ASm = 56.6 J / molK), Equation (3.33) then becomes ... 

Viscosity is an internal force of friction which acts oppositely to the flowing fluid. Walden s rule is also applicable to molten salts. Shabanov [54] applied that rule for the limiting equivalent electrical conductivities (see Figure 7) ... 

Walden s rule — This empirical rule states that the product of the equivalent -> conductivity and the viscosity of the solvent for a particular electrolyte at a given temperature is a constant. Its rational explanation is based on the Stokes-Einstein equation that connects the... 

At the boiling point, Tj, of a liquid the surface tension can be estimated from Walden s rule [5] ... 

A Very Approximate Relation between Equivalent Conductivity and Viscosity Walden s Rule... 

---