Solubility rock-salt crystals

Water-soluble crystal modifiers such as yellow pmssiate of soda (YPS) (sodium ferrocyanide decahydrate) or ferric ammonium citrate may also be added to some types of salt as anticaking agents. Both are approved by the U.S. Food and Dmg Administration for use in food-grade salt. YPS and Pmssian Blue (ferric ferrocyanide), are most commonly added to rock salt used for wintertime highway deicing. Concentrations of YPS and Pmssian Blue in deicing salt vary, typically in the range of 20—100 ppm. 

In arid environments, where the soluble products of weathering are not completely removed from the soil, saline solutions may circulate in the soil as well as in rock fractures. If upon evaporation the salt concentration increases above its saturation point, salt crystals form and grow (Goudie et al, 1970). The growth of salt crystals in crevices can force open fractures. Salt weathering occurs in cold or hot deserts or areas where salts accumulate. Boulders, blocks. 

The monosulfides of the alkaline earth metals crystallize in the rock salt (MgS, CaS, SrS, BaS) and zinc blende (BeS) structures. BaS is insoluble in water, while the other monosulfides are sparingly soluble but hydrolyzed on warming (except MgS that is completely hydrolyzed). The monoselenides are isomorphous to the sulfides. The monotellurides CaTe, SrTe, BaTe adopt the rock salt stmcture, while BeTe has the zinc blende and MgTe the wurtzite structure. Alkaline earth polysulfides may be prepared by boiling a solution or suspension of the metal hydroxide with sulfur, e.g.,... 

The rate of solution of the different faces of a crystal of rock-salt is slightly different, being rather faster on the octohedral face than on a cubic face, and intermediate between these two rates on the dodecahedral face.41 A. Ritzel has shown that in the absence of urea, the octohedral faces dissolve fastest, and in the presence of urea, the cubic faces. W. Poppe found that with 0"5 and 1"0 per cent, under-sat. soln, each crystal face dissolves at a characteristic rate, but with a 2 per cent, under-sat. soln., all the faces dissolve at approximately the same rate. The solubility of cubic and octohedral crystals per 100 c.c. of water at the end of a given time is ... 

These raw materials are mined like rock salt. The potassium chloride is separated by leaching and fractional crystallization based upon the different solubility of individual components of the starting raw material. 

Abraumsalze ) contain 55 to 65 per cent, of camallite, associated with 20 to 25 per cent, of rock-salt, 10 to 20 per cent, of kieseritc, MgS04,H20, and 2 to 4 per cent, of tachydrite, CaCl2,2MgCl2,12H20. The technical preparation of potassium chloride from these deposits depends on the ready solubility of camallite, and the crystallization of potassium chloride from hot saturated solutions of this substance.1 Kainite is employed as a source of potassium chloride, and the compound is also obtained by fractional crystallization of the salts present in sea-water and in the ash of seaweed. 

A typical phase diagram for two compounds that form a complete solid solubility over their entire composition range is shown in Fig. 8.4. Both NiO and MgO crystallize in the rock salt structure, and their cationic radii are very similar. 

Bunsenite [1313-99-1] [Named after the German chemist and spectroscopist Robert Wilhelm Bunsen(1811-1899)] (ICSD 9866 and PDF 4-835) NiO M = 74.6928 78.58 wt.%Ni 21.42 wt.% 0 (Oxides and hydroxides) Coordinence Ni(6) Cubic a = 417.69 pm Bl,cF8 (Z=4) S.G. Fm3m P.G. 432 Rock salt type Periclase group Isotropic = 2.37 5.5 6898 (6806) Habit octahedral crystals. Color dark pistachio green. Luster vitreous. Diaphaneity transparent. Streak brownie black Clivage unknown. Fracture unevea Chemical soluble with difficulty in strong mineral acids. Occurrence found in the oxidized zone of hydrothermal nickel-uranium veins along with nickel and cobalt arsenates. 

Sylvite (syn., sylvinite) [7447.40-7] [Named after the Dutch chemist and physician of Leyden, Sylvia de la Boe (1614-1672)] (ICSD 22156 and PDF 41-1476) KCl M = 74.551 52.45 wt.%K 47.55 wt.% a (Halides) Coordinence K(6) Cubic fls 629.31 pm Bl,cF8 (2 4) S.G. Fm3m P.G.4-32 Rock salt type Isotropic n = 1.490 2.0 1988 Habit massive, cubic euhedral crystals, fibrous. Color white, yellowish white, reddish white, bluish white, or brownish white. Luster vitreous, greasy. Diaphaneity transparent to translucent. Streak white. Geavage (100), (010), (001). Fracture uneven, brittle, sectile. Soluble in water, the soln. color the flame of a bunsen in violet. Bitter taste. Fusible (m.p. 778°C). 

The saltpetre of commerce is derived principally from the East Indies, where, as also in Persia, Egypt, and Spain, it appears as an efflorescence on the surface of the soil. In some other countries, as the coast of the Adriatic, in Ceylon, North America, Africa, and Tene-riffe, it is found on the walls of natural caverns formed in limestone rocks, and which contain also felspar and magnesia. It is also found widely distributed in some parts of Hungary, but in no case extending to any great depth below the surface of the ground, nor even to such a depth as the air cannot penetrate. Its appearance on the surface of the ground is explained by its ready solubility in water, as when ite solution, in obedience to the law of capillary attraction, rises to the surface, the liquid is vaporized by the action of sun and air, and its place is immediately occupied by a fresh portion from below, which disappears in the same manner, until at last an incrustation of the salt is formed of considerable thickness, either in solid crystals, or as an effloresced mass. 

There are three ways whereby salts within a rock can cause its mechanical breakdown by pressure of crystallization, by hydration pressure, and by differential thermal expansion. Under certain conditions, some salts may crystallize or recrystallize to different hydrates that occupy a larger space (being less dense) and exert additional pressure, that is, hydration pressure. The crystallization pressure depends on the temperature and degree of supersaturation of the solution, whereas the hydration pressure depends on the ambient temperature and relative humidity. Calculated crystallization pressures provide an indication of the potential pressures that may develop during crystallization in narrow closed channels (see Chapter 6). Crystallization of freely soluble salts such as sodium chloride, sodium sulphate or sodium... 

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