Na-K eutectic

In NPS Buck (USSR), the converter was an individual unit. Heat was removed from the reactor to the radiator also by a liquid-metal coolant - Na-K eutectics (Gryaznov 1999). 

Figure 1. Part of the Na-K-Cs phase diagram showing the ternary eutectic at -78 C.

Both lithium chlorate and perchlorate have been proposed as oxidizers in explosive formulations [131]. Li nitrate/K nitrate/Na nitrate eutectics (23.5/60.2/16.3) have been proposed by Kruse as oxidizers in illuminating flare formulations [132]. Similarly, LiC104 has been proposed as an oxidizer in obscurant formulations with or boron carbide(B4C) or Si. The obscuring power is mainly due to the presence of hygroscopic LiCl in the aerosol. The formulation B/LiC104 (60/40) possesses the best performance [133-135] compared with Si/Li C104 (35/65) and B4C/Li C104 (30/70) formulations. 

Fig. 5.23. The evolution of a Na-K-Cl-SO4-alkalinity brine as temperature decreases to the eutectic. Reprinted from Marion et al. (2003b) with permission...

The silver-silver Ion electrode. Of the reversible metal electrodes, silver has been most often employed. There is only one stable oxidation state of silver above 300°C there is no danger of oxide formation because Ag20 is unstable.57 The metal has no observable tendency to dissolve in molten silver salts and is highly reversible in mixed chloride and nitrate eutectics. The Ag(I) ion can be introduced into the melt by either adding silver nitrate to a nitrate melt (AgCl to a chloride melt) or by anodizing a silver electrode. The potentials of silver nitrate concentration cells show ideal thermodynamic behavior up to 0.5 mol % in (Na,K)N03 eutectic and in NaN03.58... 

In order to araise current yield of carbon phase it is advisable to use more low-melting electrolytes. For this purpose the electrolysis of C02 in the ternary eutectic Na,K,Cs Cl at temperature 500 C was carried out. In this system carbon current yield was arisen up to 80 % and the cathode product contained fullerenes phase (according to X-ray analysis) together with carbon phases obtained in NaCl - KC1 melt. 

Table 17 Composition and Melting Points of the AICI3-MCI Eutectics (M = Li, Na, K, Cs)...

Excess eutectic Na-K alloy (mp — 12°C) cleaves 2-methoxy-2-phenylpropane in Et20 to give phenylisopropylpotassium in 90-96% yield ... 

Kudo, T. Kihara, K. Hisamitsu, Y. Yu, Q. Mohamedi, M. Uchida, I. Electrochemical stability and solubility of Ni-Fe-Co ternary alloy oxides in Li/Na carbonate eutectic as an alternative material for MCFC cathodes. J. Mater. Chem. 2002, 12 (8), 2496-2500. 

M2F2-Srp2 (M = Li, Na, K). All three binary systems are the simple eutectic. Also in the same series of strontium chlorides, there are only simple eutectic systems for lithium, sodium, and potassium, but systems containing bigger rubidium and cesium cations with low polarization ability already form binary compounds. 

Janz et al. (1958) determined the freezing point depression in the eutectic mixture LiCl-KCl effected by the addition of M2Tip6 (M = Li, Na, K) in the concentration range 0.008-0.066 m, and on the basis of the experimentally measured values proposed the following dissociation scheme... 

Generally speaking, the molten KCl-LiCl eutectic (owing to its enhanced oxoacidic properties) can dissolve sufficiently larger quantities of various oxide materials as compared with chloride melts containing the constituent cations of lower acidity such as Na+, K+ and Cs+. The data... 

While discussing the obtained slope values it should be noted that the theoretical slope value calculated according the Le Chatelier-Shreder equation (3.7.19) considered above is approximately equal to 7300. This value is practically coincident with the slope in equation (3.7.55), whereas the slope in equation (3.7.56) deviates from the theoretical one by less than 20%. This seems to be explained by the fact that the chemical properties of magnesium (and Mg2+ ion) resemble those of lithium rather than the properties of the other alkaline-earth metals (it is the so-called diagonal periodicity). Therefore, the properties of MgO and Li20 in the molten KCl-LiCl eutectic are close to ideal, and the Le Chatelier-Shreder equation is correct just for such solutions. At the same time, the chemical properties of magnesium and lithium cations differ essentially from those of Na, K and Cs. 

Similar solubility behavior of polyhydroxy compounds was shown in fused acetates by Burton and Crowell. Burton observed that solubility of several organic compounds at 200°C, in (Li, Na, K) acetate eutectic (mp 180°C) increases with the number of hydroxyl groups and with acidity. In weight percent the following approximate solubilities were determined methanol, 0.05% 2,4-dinitroaniline and 4-nitroaniline, < 0.5% hydroquinone and resorcinol, 1% 2-amino-2-hydroxymethyl-l, 3-propanediol and 2-amino-2-methyl-l,3-propanediol, I0% trimethylolethane and pentaerythritol were miscible in all proportions above their melting points. 

In a search for an aprotic solvent for acidity function studies with (Li, Na, K) acetate eutectic at200°C (Na, K)SCN was suitably miscible however, even small concentrations (1 %) inhibited the known reaction of trimethylol-ethane, which probably requires proton abstraction by the acetate anion to form an alkoxide intermediate. Since haloacetates are weaker bases than acetates, these salts were considered for diluents. Potassium trifluoroacetate (mp 135-I37°C), reported to be the most stable member of the series, was prepared from potassium hydroxide and excess trifluoroacetic acid with vacuum drying and fractional recrystallization from absolute alcohol. DTA of the white crystalline product detected decomposition as low as 125°C. Since the molten salt decomposed with bubbling at I45-150°C, this effort was discontinued. 

Cryoscopic measurements in sodium nitrate indicate that this is an ionic melt. The extension of studies with organic solutes to this solvent or (Na, K)N03 eutectic (mp 233°) could give information about the solvated species, role of the solvent, and at higher temperatures the mechanism of oxidation. Based on inorganic reactions, currently there is disagreement about the existence in fused nitrates of oxide ion and nitronium ion. A fresh approach to the question with some organic reactions might help clarify the mechanism. 

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