Conductivity Method

Calcium cyanamide can be analy2ed by determining the N2 content using a combustion—conductivity method (28). 

Vulis, L. A. 1960. Regarding free turbulent jets computation applying the heat conductivity method. In Proceedings of Acad. Set. Kaz. SSR, Ser. Energy, vol. 2, no. 18. 

The reaction between peroxysulphuric acid and thiocyanate ions was investigated by Smith and Wilson by a stopped-flow conductance method. Their results can be summarized as follows. If / and m are the numbers of moles of cyanate and sulphur dicyanide produced per mole of thiocyanate consumed, the overall stoichiometric equation is... 

In the choice of an analytical technique for following the course of a reaction, it is important to recognize that no aspect of the measurement should affect the kinetic processes occurring in the system. For example, a solution conductivity method that uses platinized electrodes should not be used in the study of a reaction that is catalyzed by platinum black. 

To measure pKa values it is necessary to expose the compound to an environment of changing pH, and to monitor a particular property that changes as a function of the ionization state of the molecule. Traditional pKa methods have included solubility and conductivity methods [31]. These are slow, and require both large quantities of material and skilled operators. Some more rapid methods... 

Sowada and Warman (1982) have described a dc conductivity method for Ar gas at 295 K and 45 atm. Following a 20-ns pulse of irradiation, the conductivity rises to a peak at -50 ns, due to the Ramsauer effect, before settling to a plateau, which is ascribed to thermal conductivity since the collecting field is very low. Since there is little electron loss, the conductivity profile is proportional to the mobility profile this in turn can be considered a kind of image of collision frequency as a function of electron energy. The time to reach the conductivity plateau, -150 ns, is the measure of thermalization time in the present case. At a density of -9 X 1021 cm-3, the conductivity maximum vanishes, indicating the disappearance of the Ramsauer minimum according to Sowada and Warman. 

Extrapolation (admittedly very approximate) of the thermalization time in humid air by microwave conductivity method (Warman et al, 1984) giving tth 4.5 x 10-15 s for unit water fraction. 

Differential heating is more easily achieved with microwave technology than by conventional conductive methods and as Cundy suggested in his excellent review, could well account for apparent rate enhancements obtained by others with organic reactions on dry media [40]. 

For this range of temperature, the experimental apparatus, the shape and geometrical factor g of the sample and the method of measurement (mean conductivity method) are different from those used for the very low-temperature range. 

The thermal resistance between the ends of the sample and the copper blocks must be negligible compared with the thermal resistance of the sample. This assumption must be verified especially for short samples at low temperature where the contact resistance is higher. For this reason, a second measurement of the thermal conductivity of Torlon in the 4.2-25 K range was carried out. The second sample had a different length (L = 24.51 mm) and the same section A. This additional measurement gave the same value of k within 2%. Moreover, we see from Fig. 11.15 that data of thermal conductivity at 4.2 K well join data at lower temperatures (within 3%) obtained on a sample of much smaller geometrical factor and with a different method (integrated thermal conductivity method) and a different apparatus [38], Finally, at room temperature, we find k = 0.26 W/mK, which is the data sheet value. 

Describe the parameters that are available to the practicing chromatographer in LC, GC and SFC to conduct method development and obtain the best resolution of the components of a mixture. 

The clinical trial should be conducted methodically with clear objectives and outcomes that are statistically verifiable. The precUnical and toxicological data should have been carefully analyzed and should confirm the scientific finding. The trial should not be biased and should be able to be executed without unreasonable caveats and conditions. 

Three experimental methods that are capable of determining dissociation constants with a precision of the order of tenths of 1% have been most commonly used. Each of these methods—the cell potential method (2), the conductance method (3), and the optical method (4)—provides data that can be treated approximately, assuming that the solutions obey Henry s law, or more exactly on the basis of the methods developed in Chapter 19. We will apply the more exact procedures. As the optical method can be used only if the acid and conjugate base show substantial differences in absorption of visible or ultraviolet light, or differences in raman scattering or with the use of indicators, we shall limit our discussion to the two electrical methods. 

Mesmer et al. [7] used conductance methods to determine ionization constants over a wide range of temperatures and pressures. 

Strong et al. [8] have determined the ionization constant of benzoic acid in H2O as a function of ternperamre by conductance methods. Their data are listed in Table 20.3, with the pK based on a hypothetical standard state of 1 mol dm. Temperature was controlled to +0.002°C. 

Conductivity monitoring is most valuable for studying reactions which have very small spectral changes but which are accompanied by pH changes. The interaction of group 1 and 2 metal ions with cryptands and diaza-crown ethers has been studied by flow/conductivity methods. Conductivity monitoring has been linked to reactions which may follow pulse radiolysis, for example, in examining the... 

Stewart, A.T., Squires, G.L. 1955. Analysis of ortho- and para-hydrogen mixtures by the thermal conductivity method. J Sci Instrum 32 26-29. 

For anionic surfactant, we used sodium dodecyl sulfate (SDS). The CMC values were measured by conductance method. The CMC values were taken from the breaks of curves from plots of K/C versus N 5. Where K is the specific conductance, C is molar concentration and N is the equivalence. Figure 1 shows the CMC values of SDS at 25 °C. The curve showing in the lower left side represents data taken from literature for pure SDS. The curve showing in the upper right side represents measurements for our impure sample. Table I shows some values of (dy/dC) (C-Cq) for pure SDS at 25 °C. The values for NaCl concentrations of 0.03 M to 0.50 M are not far from constant. Therefore, in this concentration region, t is also considered to be proportional to M. 

Tip 1 Principle (a noun) a basic truth or assumption a standard a guiding rule, code of conduct, method of operation a rule or law concerning the functioning of natural phenomena or mechanical processes ... 

The direct mode is employed with eluents with significantly lower equivalent conductance than the analyte ion. Increase in sensitivity is obtained as the degree of the ionization of the eluent decreases, that is, with more weakly dissociated eluents, and non suppressed conductivity methods have been extensively developed using benzoate, phthalate [246], oxalate [53] or other partially ionized species as mobile phases. A key factor in the success of this technique is the use of an ion exchanger of low-exchange capacity, which in turn permits the use of a very dilute eluent. 

In a pulse-radiolysis d.c. conductivity method, is measured and then is determined from the measured kj and a separately known In a pulse-radiolysis charge-clearing method, a residual amount of charge that is left unrecombined is collected and measured. Because the collected charge is expressed as a function of k, the value of where is a correction factor due... 

In a pulse-radiolysis d.c. conductivity method with a long pulse width, the resulting steady state current during the long pulse is considered by the assumption that the rate of excess electron generation becomes equal to the rate of electron loss because of the reaction with positive ions and impurities. 

In a pulse-radiolysis microwave-conductivity method, the kr value is determined by the time-resolved measurement of microwave conductivity. 

Cation Anion Temperature (K) Conductivity (Kj, mS cm Conductivity method Viscosity (% cP... 

Heat Tests. Under this term may be placed all the stability tests which involve heating an explosive, eg Abel Heat Test, Acidity Measurements (pH measurements), American Test at 65.5° or 80°, Bergmann-Junk Test, Brame s Test, Brunswig s Test, Chiaraviglio Corbino Test, Conductivity Method (De Bruin de Pauw) Continuous Test, Deflagration Test, Desmaroux Test, Dupre s Vacuum Test, Dutch Test,... 

All data obtained on the rate of reaction of [Ni(NiL2)2]Cl2 with alkyl halides— i.e., methyl iodide, benzyl bromide, benzyl chloride, p-nitrobenzyl chloride, p-chlorobenzyl chloride, ethyl bromide, ethyl iodide, n-propyl bromide, and n-propyl iodide—conform closely to a pseudo-first-order rate law. Almost all experiments were carried out in the presence of an excess of alkyl halide. Since methanol solutions of the alkylated complexes have only negligible absorption at 495 m//, rates were obtained by graphs of log A0—A vs. time. The graphs are linear over the entire time interval, which corresponds to more than two half lives in most cases, passing through the origin at zero time. The rate is essentially the same whether measured by the spectrophotometric or conductivity method. 

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