Partial specific conductance

Conductivity grade benzonitrile (specific conductance 2 x 10" mho) was obtained by treatment with anhydrous AICI3, followed by rapid distn at 40-50° under vacuum. After washing with alkali and drying with CaCl2, the distillate was vac distd several times at 35° before being fractionally crystd several times by partial freezing. It was dried over finely divided activated alumina from which it was withdrawn as required [Van Dyke and Harrison J Am Chem Soc 73 402 7957]. 

Selenium monoehloride is a clear reddish-brown liquid of density (D lT) 2-7741, and can be condensed to a solid of melting-point —85° C.7 Its odour somewhat resembles that of sulphur monoehloride. The liquid has a refractive index of 1-59617 at 25° C-, and its specific conductance is 5-12 X10-7 mho. On vaporisation it undergoes partial dissociation. Boiling commences at 145° C., the yellowish-brown vapour containing the tetrachloride and a residue of selenium being obtained in the retort 8... 

Unlike weak electrolytes, solutions of strong ones have a far higher specific conductance the rise of the latter with rising concentration is also much more rapid. There is another difference the anomalies ascertained in the colligative properties of strong electrolytes cannot be ascribed to partial dissociation of molecules to ions as in the case of weak electrolytes. 

The specific conductivity of solutions with the same concentration decreases in the sequence toluene > meta-xylene > cumene > diphenylmethane > j3-isopropyl-methylbenzene > tetralin [242]. The decrease in conductivity in high-boiling hydrocarbons can be partially compensated for by increasing the temperature from 95 to around 130 °C [129, 130]. 

The conductivity of Nafion 117 (EW 1100), Membrane C (EW 900), and Dow membranes (EW 800) at 30 °C was measured by Zawodzinski et al. [58-60] for membranes immersed in liquid water and for partially hydrated membranes in contact with water vapor. The conductivity of Nafion 117 decreases roughly linearly with decreasing water content, as shown in Fig. 32. The value of the conductivity measured at A = 14 (saturated vapor), 0.06 0.01 S/cm, agrees with the value previously reported by Rieke and Vanderborgh [62]. The dependence of conductivity on water content for Membrane C and Dow membranes is somewhat more complicated. In both cases, the conductivity decreases roughly linearly with decreasing water content until an apparent threshold is reached, at which point the conductivity drops substantially (Fig. 32). Above the water content where the steep drop occurs, the specific conductivity of both membranes is substantially higher than... 

Since the values of the thermal diffusivity for myoglobin and water are close, the discrepancy between their thermal conductivities is largely due to differences in their respective heat capacities. At 300 K the specific heat of water is 4.2 J K 1 g-1, whereas we calculate the specific heat of myoglobin to be 1.0 J K 1 g 1 at 300 K. This latter value is reasonably close to measured specific heats for proteins. For example, the specific heat of lysozyme in dilute aqueous solution is 1.5 J K-1 g , and it is 1.3 J K-1 g-1 for the dry protein [154,155]. Still, we should bear in mind that at 300 K the partial specific heat of a hydrated protein may be some 50% larger than the specific heat of a dry protein [156], so that the coefficient of thermal conductivity may be correspondingly larger. 

The most accurate value of ionic strength is obtained from a total water analysis, which includes all ionic species. However, partial analyses are more commonly available than complete ones. Under such conditions the molal ionic strength can be estimated from the total dissolved solids or specific conductance of the water (cf. Langmuir and Mahoney 1985 Polemo et al. 1980). Expressions that permit such an approach are ... 

Other properties of algin reported include conductivity (252 253), contact angles of various solvents on different metal alginate films 175), depolymerization rates for alginic acid in various acids (251, 25U, 255), a pK of 2.95 for the dissociation constant of alginic acid in normal potassium chloride solution (208), absorption spectra of algin (202), and properties determined in connection with molecular weight studies, such as sedimentation and diffusion velocity and partial specific volumes (209),... 

For initiation in micelles, the emulsifier concentration must exceed the cmc. The classical concept of the cmc is that it represents that concentration at which micelles form at higher concentrations, more micelles form, and at lower concentrations, no micelles are present. The cmc is usually determined by the inflection point in some physical property measured as a function of emulsifier concentration. Figure 1 shows a schematic illustration of the variation of conductivity k, turbidity t, equivalent conductivity X, surface tension y, and osmotic pressure tt with sodium dodecyl sulfate concentration (18). All five parameters show an inflection point at ca. 8mM, which is the most common value of the cmc, and all five curves are consistent with the concept of micelles forming above ca. 8mM and not forming at lower concentrations. Recent measurements of the partial specific volume of sodium lau-ryl sulfate solutions (19), however, suggest that aggregates of lauryl sulfate ions are present of concentrations well below the cmc. 

FIGURE 8.4. Cell arrangement for the measurement of the partial ionic conductivity using an SE as an electronblocking electrode. Specific example the MIEC conducts Li+ ions and electrons/holes. The polarity of the applied voltage is fixed accordingly. E(Li) reversible electrode with a fixed Plj. 

FIGURE 8.8. Linear cell configuration for measuring differences Aflj in MIECs and electrode overpotentials, using four electrodes. The arrangement, which includes three SEs, can also serve to determine the partial ionic conductivity of the MIEC. Specific example the MIEC conducts ions. E(M) electrode with fixed pn,. 

On account of the high ionic concentration — as already discnssed in detail above — the concentrations of the silver defects in the space charge zone are not dependent on the silver activity or the partial pressvue of chlorine. In contrast, the local electronic concentration and electronic local specific conductivity are pronounced functions of the component activities, according to Ng/ = Ng/oo = —1/2 and Nh = Nh oo = -M/2 ... 

Temperature rc) Humidity kg HjO/kg dry air) Water vapor partial pressure (kPa) Water v K>r partial density (kg/m ) Water vaporization heat M/kg) Mixture enthalpy (kj/kg dry air) Dry air partial density (lKinematic viscosity (I0< mJ/s) Specific heat (kJ/K kg) Heat conductivity (W/m K) Diffusion factor water air (1 O mJ/s) Temperature rc)... 

The terms zonal model and flow element are also used for the simplified characterization of the flow field in a single enclosure. There, a zone represents a partial volume of air in the enclosure, whereas in the multizone models described here, a zone represents a specific enclosure which is connected to other enclosures by air conductances (see The Airflow Network later). 

Particular examples of using polymer composites as screens are given in [14-16, 67-75], The present review does not touch the properties of the composite materials based on fabrics of conducting fibres due to the fact that manufacturing techniques for such materials are specific and differ greatly from the mixing processes considered above. However, these materials also have an application field, say, in contacts for calculator and computer keyboards [9] and even in small-power electric motor commutators as a partial substitute for copper [76, 77]. 

---