Melting-point curve

Fig. 74. IR spectra of KfTaF-j at ambient temperature (curve 1), at melting point (curve 2) and at 850°C (curve 3) (after Agulyansky, Kirillov, Prisyagny [356]).

In order to achieve efficient build-up to heavy depths when dyeing cellulose acetate at 80 °C it is customary, particularly for navy blues, to use a mixture of two or more components of similar hue. If these behave independently, each will give its saturation solubility in the fibre. In practice, certain mixtures of dyes with closely related structures are 20-50% less soluble in cellulose acetate than predicted from the sum of their individual solubilities [87]. Dyes of this kind form mixed crystals in which the components are able to replace one another in the crystal lattice. The melting point depends on composition, varying gradually between those of the components, and the mixed crystals exhibit lower solubility than the sum of solubilities of the component dyes [88]. Dyes of dissimilar molecular shape do not form mixed crystals, the melting point curve of the mixture shows a eutectic point and they behave additively in mixtures with respect to solubility in water and in the fibre. 

Fig. 4.1. Melting point curve of a hypothetical substance, having a melting point around 45°C.

B. melting point curve of (+) mandelic and (+) hexahydro-mandelic acid. 

J. C. Randall, Phillips Petroleum, Oklahoma I was interested in your linewidth curves vs temperature in which you essentially had the melting point curves. Did you do any freezing point curves ... 

D. Axelson These were obtained for branched polyethylene and were similar to the melting point curves. The conditions were such that either direction gave identical linewidths. 

Fio. 101.—Melting-point Curve of Mixtures of Nitric Oxide and Bromine. 

Si02 (liq.). From melting point curves, Kracek1 calculated the heat of fusion of cristobalite to be —1.84 at 1530°. 

Curve BC Similarly, B represents the melting point of pure silver. By the addition of lead to it, the freezing point of silver decreases along BC and we get a solution of it with lead. The curve BC is known as the freezing point or melting point curve of silver. The two phases present along it are solid silver and a solution of it with lead. It is, therefore, a univariant curve as,... 

Alkane melting points. The melting-point curve for w-alkanes with even numbers of carbon atoms is slightly higher than the curve for alkanes with odd numbers of carbons. 

An accurate melting point curve of mixtures of o- and p-nitrochlorobenzenes has been given by Holleman and de Bruyn.2 From this curve, it is possible to determine directly the composition of ai mixture. 

Melting point curves where Solid Solutions are formed. 

Here again the conditions of true equilibrium A 2 = will be satisfied at all points on the melting point curve (c/. fig. 15.3). 

Besides their use as criteria of purity, melting-point data are extensively used in the identification of carbon compounds. The melting point usually restricts the identification to a few com-poimds which have approximately the same melting point. For this purpose, melting-point curves of mixtures are used for ex-... 

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