Phase diagram potassium-sodium

The composition data obtained for the series of mixed fatty acid-potassium soap systems, prepared by both the ethanol and petroleum ether routes, lend strong support to the formation of 1 to 1 acid-soap complexes. It is of interest to inquire into the phase relationships in these two-component systems. A phase diagram presented by McBain and Field (15) for the lauric acid-potassium laurate system shows that compound formation takes place between the two components at the 1 to 1 molar ratio, but the compound undergoes melting with decomposition at 91.3 °C. [A similar type of phase behavior has been reported by us for the sodium alkyl sulfate-alkyl alcohol (9) and sodium alkyl sulfonate-alkyl alcohol (12) systems, but in these cases the stoichiometry is 2 to 1]. 

Figure 16.2. Some phase diagrams, (a) The water end of the system potassium chloride and water, (b) The water end of the system sodium chloride and water, (c) The water end of the system magnesium sulfate and water the heptahydrate goes to the mono at 150°C, and to anhydrous at 200°C. (d) /3-methylnaphthalene and /S-chloronaphthalene form solid solutions, (e) Mixtures of formamide and pyridine form a simple eutectic, (f) These mixtures form binary eutectics at the indicated temperatures and a ternary eutectic at mol fractions 0.392 dibenzyl, 0.338 diphenyl, and 0.27 naphthalene.

Experimental Information. The review by Ekwall — offers a whole series of phase diagrams which all show similar behavior. In order to dissolve an anionic surfactant with a sodium counter ion in an alcohol a minimum water/surfactant molar ratio of about six is needed to achieve solubility. The corresponding ratio for the potassium ion is three. 

The sodium polyphosphate systems produce glasses very easily while it is difficult to make potassium glasses. The milky glassy masses of potassium metaphosphate compositions obtained by quenching the potassium melts are rich in potassium trimetaphosphate, though the phase diagram for the system contains none. Potassium cyclic triphosphate can be made thermally by dehydrating monopotassium orthophosphate with urea at temperatures less than 300 C,... 

The melting point of pure zirconium trichloride could not be obtained because of disproportionation. Attempts to determine the phase diagram for the sodium chloride system failed because of excessive disproportionation. In the potassium chloride-zirconium trichloride system the eutectic temperature was 581° 2°C. A mixed system was used, however, since it was found that the stability of the trichloride was satisfactory in a 50 50 sodium chloride potassium chloride melt. Powder patterns of the frozen melt at 15 mole% zirconium trichloride which had been at 750°C for 24 hours showed no evidence of the dichloride and tetrachloride. There was evidence for slight solubility of the trichloride in the solid at this composition. The reaction of zirconium metal with the trichloride in the equimolar sodium-potassium chloride melt revealed that even after the trichloride had been reduced to the dichloride, zirconium metal dissolved to the extent of 5 x lO" or 10 mole fraction of excess metal in the solution. Zirconium metal did not, however, appear to dissolve in the melt in the absence of zirconium dichloride. 

The structure in the micellar region of the phase diagrams of potassium soaps has been analysed by Reiss-Husson and Luzzati (1969) using X-ray methods. A common feature in soaps of saturated fatty acids is that spherical micelles exist at low concentrations, and at increased concentrations a transition into rod micelles occurs. Sodium oleate, however, was found to give rod-shaped micelles at all concentrations. The micellar association and phase behaviour have been reviewed by Wenner-strom and Lindman (1979) and Lindman and Wennerstrom (1980). 

The sodium-potassium system has been the most fully explored because at one time it seemed possible that the eutectic mixture (NaK) might become the accepted coolant for fast nuclear reactors. At the eutectic composition, 67.8 at.% potassium, the mixture is liquid at temperatures down to -12.5°C. This low temperature relative to the melting points of the two pure metals (97.8 and 63.2°C, respectively) is remarkable and must be related to their different atomic sizes. An inflection in the phase diagram suggests the presence of a compound NaaK presumably the atoms can pack into a solid stmcture of this composition, and there is no evidence of NaaK... 

Unlike the sodium systems, melt history has less influence on potassium Kurrol s salt systems mentioned above. Potassium trimetaphosphate is not a phase diagram entity. Potassium phosphate melts with R values of unity are very difficult to quench to glasses, because they crystallize very rapidly. If potassium phosphate melts are cooled slowly, long-chain polyphosphates, [KPOsln, are the only crystals to form. No other crystals are thermodynamically stable in this portion of their phase diagram and Kurrol s salts dominate a large area of this diagram. 

Zafarami-Moattar MT, Banisaeid S, Shamsi Beirami MA (2005) Phase diagrams of some aliphatic alcohols + potassium or sodium + water at 25 °C. J Chem Eng Data 50 1409-1413... 

The electrical properties of the alkali metal salt complexes are of interest as solid electrodes for batteries (27, 27a). There is particular interest in alkali metal-thiocyanate salt complexes this interest is related to the anion having a high lyotropic number and a correspondingly high conductivity (see Table 4). The complete phase diagram has been published for the potassium thiocyanate/ and sodium/thiocyanate/polyethylene glycol system (28), and various thermodynamic properties have... 

Orthophosphate salts are generally prepared by the partial or total neutralization of orthophosphoric acid. Phase equiUbrium diagrams are particularly usehil in identifying conditions for the preparation of particular phosphate salts. The solution properties of orthophosphate salts of monovalent cations are distincdy different from those of the polyvalent cations, the latter exhibiting incongment solubiUty in most cases. The commercial phosphates include alkah metal, alkaline-earth, heavy metal, mixed metal, and ammonium salts of phosphoric acid. Sodium phosphates are the most important, followed by calcium, ammonium, and potassium salts. 

Fig. 5. Tentative mixed potential model for the sodium-potassium pump in biological membranes the vertical lines symbolyze the surface of the ATP-ase and at the same time the ordinate of the virtual current-voltage curves on either side resulting in different Evans-diagrams. The scale of the absolute potential difference between the ATP-ase and the solution phase is indicated in the upper left comer of the figure. On each side of the enzyme a mixed potential (= circle) between Na+, K+ and also other ions (i.e. Ca2+ ) is established, resulting in a transmembrane potential of around — 60 mV. This number is not essential it is also possible that this value is established by a passive diffusion of mainly K+-ions out of the cell at a different location. This would mean that the electric field across the cell-membranes is not uniformly distributed.

If we refer to the MR -2R -3R diagram, the pole MR (feldspar) would become sodic as temperature increases while the mixed layered phase becomes potassic. If we consider calcium in this system, it will not form a feldspar as does sodium and must enter into solution or be precipitated as carbonate when montmorillonite layers decrease in the mixed layered phase. In either event the net effect is to reduce the potassium part... 

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