Aqueous solutions of NaCl

The Debye-Htickel limiting law predicts a square-root dependence on the ionic strength/= MTLcz of the logarithm of the mean activity coefficient (log y ), tire heat of dilution (E /VI) and the excess volume it is considered to be an exact expression for the behaviour of an electrolyte at infinite dilution. Some experimental results for the activity coefficients and heats of dilution are shown in figure A2.3.11 for aqueous solutions of NaCl and ZnSO at 25°C the results are typical of the observations for 1-1 (e.g.NaCl) and 2-2 (e.g. ZnSO ) aqueous electrolyte solutions at this temperature. 

Figure Bl.20.8. DLVO-type forces measured between two silica glass surfaces in aqueous solutions of NaCl at various concentrations. The inset shows the same data in the short-range regime up to D = 10 mn. The repulsive deviation at short range (<2 nm) is due to a monotonic solvation force, which seems not to depend on the salt concentration. Oscillatory surface forces are not observed. With pemiission from [73].

Single-Bubble Sonoluminescence. The spectra of MBSL and SBSL are dramatically different. MBSL is generally dominated by atomic and molecular emission lines, but SBSL is an essentially featureless emission that iacreases with decreasiag wavelength. For example, an aqueous solution of NaCl shows evidence of excited states of both OH- and Na ia the MBSL spectmm however, the SBSL spectmm of an identical solution shows no evidence of either of these peaks (30). Similady, the MBSL spectmm falls off at low wavelengths, while the SBSL spectmm continues to rise, at least for bubbles containing most noble gases (38). 

It is clear that, if synthetic routes could be devised which would mechanistically hinder disproportionation, such compounds might be preparable. Although univalent compounds of the Group 2 metals have not yet been isolated, there is some evidence for the formation of Mg species during electrolysis with Mg electrodes. Thus H2 is evolved at the anode when an aqueous solution of NaCl is electrolysed and the amount of Mg lost from the anode corresponds to an oxidation state of 1.3. Similarly, when aqueous Na2S04 is electrolysed, the amount of H2 evolved corresponds to the oxidation by water of Mg ions having an average oxidation state of 1.4 ... 

The electrolysis of an aqueous solution of NaCl has the overall equation... 

Show that when an aqueous solution of NaCl is being electrolyzed, vigorous stirring in the cell might permit reaction (23) to occur. 

E5.5 The following equation has been found to represent the volume of aqueous solutions of NaCl at T= 298.15 K and p = 0.101 MPa that contains 1.000 kg of water... 

Cataldo F (1992) Effects of ultrasound on the yield of hydrogen and chlorine during electrolysis of aqueous solutions of NaCl or HC1. J Electroanal Chem 332 325-331... 

However, if you electrolyze a dilute aqueous solution of NaCl, the water is decomposed. (The NaCl is necessary to conduct the current, but neither the Na+ nor the Cl- reacts at the electrodes.)... 

Due to the very time consuming of the above procedure, the latter was modified as follows (synthesis B) equal volumes of silicate and Al-Pr4N+-H2SO, solutions were added at the same rate to an aqueous solution of NaCl (Merck, anal, grade). The gel which is formed (pH 3.5), is stirred for 2 h before its pH is adjusted to about 9-9.5 by further adding of the remaining excess of Na silicate solution. The so obtained gel is stirred for 3 h before heating. 

You are given an aqueous solution of NaCl. The simplest method for the separation of NaCl from the solution is... 

SOLUTION and MIXTURE - There is some confusion between these two terms in geological literature. According to the I.U.P. A.C. (International Union for Pure and Applied Chemistry), the term mixture must be adopted whenever all components are treated in the same manner , whereas solution is reserved for cases in which it is necessary to distinguish a solute from a solvent. This distinction in terminology will be more evident after the introduction of the concept of standard state. It is nevertheless already evident that we cannot treat an aqueous solution of NaCl as a mixture, because the solute (NaCl) in its stable (crystalline) state has a completely different aggregation state from that of the solvent (H2O) and, because NaCl is a strong electrolyte (see section 8.2), we cannot even imagine pure aqueous NaCl. 

The electrical potential across a LB film of dioleoyl-lecithin deposited onto a fine-pore membrane, imposed between equimolar aqueous solutions of NaCl and KC1, was reported to exhibit rhythmic and sustained pulsing or oscillations of electrical potential between the two solutions. These oscillations were attributed to the change of permeability of Na+ and K+ ions across the membrane, which originated from the phase transition of lecithin. 

Electrolyzing an aqueous solution of NaCl using copper electrodes.The technical grade product should contain minimum 97% CU2O for use in pigments. 

A student prepares an aqueous solution of NaCl and performs an electrolysis experiment. The products at the cathode would be... 

Calculate the Debye lengths for 0.1 mM, lOmM and lOOmM aqueous solutions of NaCl and MgS04, assuming that the salts are completely ionized. 

Vogl et al. 59-60> prepared regular copolyamide membranes. They condensation-polymerized isophthaloylchloride with N,N -bis(2-aminoethyl)oxamide, which was prepared from ethylenediamine and diethyloxalate, to give the polymer 14. The salt rejection of the membrane was 77.5 99.0% for 1% aqueous solution of NaCl at 25 °C and 70 kg/cm2 but the water flux was not very high. 

Another claim for an apparent mean-field behavior of ionic fluids came from measurements of heat capacities. The weak Ising-like divergences of the heat capacities Cv of the pure solvent and CPtx of mixtures should vanish in the mean-field case (cf. Table I). The divergence of Cv is firmly established for pure water. Accurate experiments for aqueous solutions of NaCl... 

While the early work on molten NH4CI gave only some qualitative hints that the effective critical behavior of ionic fluids may be different from that of nonionic fluids, the possibility of apparent mean-field behavior has been substantiated in precise studies of two- and multicomponent ionic fluids. Crossover to mean-field criticality far away from Tc seems now well-established for several systems. Examples are liquid-liquid demixings in binary systems such as Bu4NPic + alcohols and Na + NH3, liquid-liquid demixings in ternary systems of the type salt + water + organic solvent, and liquid-vapor transitions in aqueous solutions of NaCl. On the other hand, Pitzer s conjecture that the asymptotic behavior itself might be mean-field-like has not been confirmed. 

Finally, we recall that in high-temperature aqueous solutions of NaCl near the L-G critical line, crossover has also been observed. Again, it has been concluded [152] that the critical locus may be affected by a virtual tricritical point. 

From a global assessment of these results, it seems inescapable to conclude that mean-field behavior does not remain valid asymptotically close to the critical point. Rather, ionic systems seem to show Ising-to-mean-field crossover. Such a crossover has been a recurring result observed near liquid-liquid consolute points in Coulombic electrolyte solutions, in ternary aqueous electrolyte solutions containing an organic cosolvent, and in binary aqueous solutions of NaCl near the liquid-vapor critical line. 

PROBLEM 11.5 Assuming that seawater is an aqueous solution of NaCl, what is its molarity The density of seawater is 1.025 g/mL at 20°C, and the NaCl concentration is 3.50 mass %. 

A constant current of 30.0 A is passed through an aqueous solution of NaCl for a time of 1.00 h. How many grams of NaOH and how many liters of Cl2 gas at STP are produced ... 

In summary, while the nonionic surfactant dimethyldo-decylamine oxide forms only spherical micelles even in 0.20 M NaCl (see above and ref. 498), micelles of dimethyloleylamine oxide are subject to a sphere-rod equilibrium in aqueous solutions of NaCl as dilute as 10 4 M and even in water alone (ref. 500). Thus, Imae and Ikeda (ref. 479) conclude the rodlike micelles are stabilized more, as compared with the spherical micelles, when the hydrocarbon chain of the surfactant molecule is longer. This conclusion is, therefore, consistent with the earlier-mentioned belief of these authors that the rodlike micelles are more stable when the polar head group of the surfactant molecule is smaller and the chain length of its hydrocarbon part is longer (ref. 473). Since the surfactants referred to all behave as nonionics, these findings of rodlike micelle production have direct relevance to the formation of artificial gas microbubbles (see Section 10.3) with either the earlier-mentioned surfactant mixture Filmix 3 (see Chapter 9 and Section 10.4) or another, related surfactant preparation (see Section 10.4). 

In a liquid solution, the dissolved substance is called the solute, the liquid in which the solute is dissolved is the solvent. Usually the distinction is clear and unambiguous, e.g., in an aqueous solution of NaCl, sodium chloride is the solute, water the solvent. In a mixture of two liquids, e.g., water and methanol, CH3OH, the designation of solvent and solute may be entirely arbitrary. 

Gates JA, Wood RH (1985) Densities of aqueous solutions of NaCl, MgCl2, KC1, NaBr, LiCl, and CaCl2 from 0.05 to 5.0 mol kg-1 and 0.1013 to 40 MPa at 298.15K. J Chem Eng Data 30 44-49 Gibbs JW (1948) The collected works of J. Willard Gibbs. Yale University... 

Five grams of dry anion exchanger were used. The amount of each anion exchanger was calculated using the dry content (Table 1). All anion exchangers were swollen in a saturated aqueous solution of NaCl, then converted to OH form with alM solution of NaOH, and finally washed with Milli-Q water (Millipore, Billerica, MA) until the pH was neutral. 

Fig. 2.11. Salt distributions in sand agglomerates [26] (31—44/im sand saturated aqueous solution of NaCl as bridging liquid dried at 110° C. (a) agglomerates contained no gelling agent (b) bridging liquid contained 10% w/v corn starch).

Fig. 10.6. Mean activity coefficient of aqueous solutions of NaCl, KC1, and CaCb...

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