Eutonic

Iron-nickel alloys are known to dissolve in the aluminium melts non-selectively. " As seen from Table 5.3, during dissolution of a 50 mass % Fe-50 mass % Ni alloy the ratio, cFe cNi, of iron to nickel concentrations in the melt is 1.00 0.05, i.e. it is equal to that in the initial solid material. The same applies to other alloys over the whole range of compositions. Respective saturation concentrations are presented in Table 5.4. The data obtained display a strong mutual influence of the elements on their solubilities in liquid aluminium because in its absence the solubility diagram for a constant temperature would be like that shown by the dotted lines in Fig. 5.5, with the eutonic point, E, at 2.5 mass % Fe and 10.0 mass % Ni. The effect of iron on the nickel solubility is seen to be more pronounced than that of nickel on the iron solubility. 

The experiments provided information for the sequence of salt crystallization from different brines under different conditions. It was shown that for these brines the crystallization sequence is similar and the quantity of evaporated water prior to commencement of the sedimentation of the salt reaches the eutonic differences could be explained by the hydrogen ion impact on the crystallizing salt solubility ... 

In addition to the above data, the author also gives the composition of the respective eutonic solution as 9.14 mass% Na2HP0. (0.91 mol/kg—compiler) 20.33 mass% NaCl (4.93 mol/kg—compiler), and 70.53 mass% water. 

Conventional measurements were made on aliquots of saturated solutions. The ammonium salt was determined gravimetrically as ammoniumtetraphenylborate (1) and the total salt content was determined by evaporation to constant weight in vacuum over H2S0. The sodium salt was then estimated by difference. The composition of the eutonics was checked by an isopiestic method (2). 

Binary eutonic solutions were prepared on No information is given. 

The authors state that, in fields where salts other than KCl exist as equilibrium solid phases, the precision of the results is poor because of the high viscosity of the saturated solutions. For the same reason, the authors could not determine the composition of eutonic solutions at 50 C and 75°C. They estimate that these solutions contain about 3% KCl at 50°C and less than 2% KCl at 75°C. 

There is also uncertainty with respect to the degree of hydration of the tripotassium phosphate. Ravich (1) reported the existence of a stable heptahydrate and trihydrate and a metastable enneahydrate. However, it is possible that there is some error in his assignment of stability and metastability to the eutonic solutions.. Some authors (2,6) also report the existence of an octahydrate as the stable phase at room temperature, but neither Ravich (7,8) nor Berg (9-11) observed an octahydrate in their detailed studies of the K2O-P2O5-H2O system. Therefore, the evaluator concludes that the existence of the octahydrate has not been established. 

The System is reported to be of the eutonic type and a saturated solution in equilibrium with both CSH2PO4 and CsCl has the composition 0.58 mol/kg CSH2PO4 and 10.5 mol/kg CsCl. 

The two-dimensional p-T projection or triangle prism of T-x and p-x projections can be used for correct representations of mono- and nonvariant equilibria over the wide ranges of temperature and pressme. Sometimes the three-dimensional T-x or p-x projection can be drawn as a triangle of ternary concentrations with a set of isotherms or isobars, which describe the phase behavior in a range of temperature or pressme. Usually such triangles are used to show only one surface. For instance, a critical smface or a surface of liquid phase composition in equilibrium with other phases in a wide range of ternary composition, or the borders between several adjacent surfaces - the eutonic curves (L-G-Sb-Sc) between the two solubility smfaces of several nonvolatile components. 

X Kci = 100 Wkci/(Wkci + WNaci), where Wkci and WNaci are the weight amounts of KCl and NaCl in aqueous solution (solvent-free concentration) temperature near isotherms (a) shown in °C pressure near isobars (b) shown in MPa. Heavy lines are the composition of eutonic solutions saturated with two solid phases at vapor pressure solid lines show (a) the isothermal composition of solid saturated liquid solutions at vapor pressure and (b) the composition of solid saturated liquid solution at constant vapor pressure. 

Figure 1.46 p-T projections of the three-phase solubility curves (L-G-S) in binary systems of type 1 (solid lines), and eutonic curves (L-G-S 1-S2) (dashed lines) in ternary systems of types la-la-la (H2O - KCl - NaCl) and la-la-2d (H2O - KCl - K2SO4, H2O - NaCl - Na2S04, H2O - KF - LiF) and liquid-gas curve for pure H2O (heavy line) (From Elsevier). 

The phase diagram in Fig. 13.18 on the next page is for a ternary system of water and two salts with an ion in common. There is a one-phase area for solution, labeled sin a pair of two-phase areas in which the phases are a single solid salt and the saturated solution and a triangular three-phase area. The upper vertex of the three-phase area, the eutonic point, represents the composition of solution saturated with respect to both salts. Some representative tie lines are drawn in the two-phase areas. 

The solubility isotherm at 25°C was established and the solid phase compositions were determined by Schreinemakers method. The system is eutonic. The eutonic point is at 8.23 wt% Nd2(Se04)3 and 37.16 wt% Yb2(Se04)3. Solid solutions based on Nd2(Se04)3 5H20 are observed for up to 70.09 mol% Yb2(Se04)3 beyond that mixed crystals based on... 

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