Solvent Equilibria of AlCl[sub 3]-NaCl Melts

Abstract

The solvent acid‐base properties of AlCl3‐normalNaCl melts containing 50–70 mole per cent AlCl3 at temperatures of 175°–355°C are fully described by the use of three equilibrium constants 2AlCl3)(1=Al2Cl6)(1 Knormalo AlCl4−+AlCl3=Al2Cl7− K2 2AlCl4−=Al2Cl7−+Cl− KM At 175°C the K values on the mole fraction scale are 2.86×107,2.4×104,normaland 1.06×10−7 , respectively. The ΔH and ΔS values for each equilibrium were found to be temperature independent and calculated values for previously unreported formation constants for the liquid NaAlCl4 , NaAl2Cl7 , and Al2Cl6 species are reported. Emf data for the aluminum electrode AlCl4−+3e−=normalAl↓+4Cl− determined as a function of the mole per cent AlCl3, are used to evaluate the equilibrium constants. In the calculations it was necessary to use a variable AlCl4− activity coefficient when the mole per cent AlCl3 exceeded 50%. An experimental nondestructive in situ procedure for the determination of the exact composition and pCl of any melt is described. This procedure is essential when working in volatile melts.

Mathematical Modeling of the Sodium/Iron Chloride Battery

“…The parameters shown in Table 1 given by Boxall et al [16] were used to determine equilibrium [21] (27)…”

“…The electrolyte is a molten AlC1 3 -NaCl salt saturated with NaCl and can be treated as a concentrated mixture of Na +, A1Cl 4 and Cl [ 16] .…”

On the Tetrachloroaluminate Dissociation in Aluminum Chloride‐1‐n Butylpyridinium Chloride Mixtures

“…The necessary equilibrium formation constant Ks was found much too high (six order of magnitude) with respect to what is expected by extrapolation at room temperature of K2 constants known for inorganic chloroaluminates (3). Another explanation involves the fact that the exact formulation of the emf is given by (33) II tA I ( ... ) [9] In the preceding calculations, only the first term is taken into account.…”

“…Another explanation involves the fact that the exact formulation of the emf is given by (33) II tA I ( ... ) [9] In the preceding calculations, only the first term is taken into account. For titration curves involving inorganic chloroaluminate, it has been generally accepted that either the last two terms are indeed negligible (2,3) or can be calculated based on the assumption that the cation is the only current carrying species (4) 9 In agreement with the work by King and,~ye (33), for room temperature organic chloroaluminate melts, the organic cation cannot be considered with certainty as the only current carrying species because of its much larger size with respect to the inorganic cation 9 By measuring conductivities of various molten methylpyridinium halides, Newman et al concluded that the principal charge carrier is the anion simply because chloride melts are better conductors than bromide melts. However, such a simple conclusion cannot be made when comparing the conductivities of several alkylpyridinium halides where both the alkyl chain and the halide were changed (29).…”

Electroless Growth of Aluminum Dendrites in NaCl ‐ AlCl3 Melts

“…The concentration overvoltage corresponds to the reversible cell potential of the following concentration cell A1/NaC1-A1C13(jNaC1-A1C13cb~/A1 where subscripts (s) and (b) indicate the surface and bulk concentrations of both aluminum-containing species and sodium chloride, respectively. Such a cell should exhibit a cell potential corresponding to electrode reaction [1] such as (17) R…”