Alkaline earth salt hydrates

As water is a possible impurity in solvent NMA, it is somewhat reassuring that values for Aq for some of the hydrated and anhydrous alkaline earth salts agree so well. This also suggests that the ions in question are probably solvated moderately well in dilute solution by NMA molecules in competition with water molecules. 

The alkaline earth halide hydrates and related salts have been studied by TG and other thermal techniques under a variety of atmospheric and instrumental conditions. Using the quasi-isothermal and quasi-isobaric techniques in different types of sample holders, Paulik et al. (61) found that various hydrate stoichiometries could be obtained. As shown in Figure 4.8, the inflection points in curve (/) indicate the presence of CaBr2-2H20 and CaBr2 H20. In curves (2)-(4), the inflection points correspond 10 CaBr2-3H20 and... 

The peroxide hydrates are formed when alkaline solutions of alkaline earth salts are treated with HgOg. To avoid the formation of dihydrates or of anhydrous salts, the following directions must be complied with when working with a Ca salt, for example 11 g. of CaClg. 6HgO is dissolved in 5 ml. of HgOand treated with 50 ml. of 3% HgOg. To this solution, 7 ml. of 25% ammonia in 100 ml. of HgO is added. 

Barium is a member of the aLkaline-earth group of elements in Group 2 (IIA) of the period table. Calcium [7440-70-2], Ca, strontium [7440-24-6], Sr, and barium form a closely aUied series in which the chemical and physical properties of the elements and thek compounds vary systematically with increa sing size, the ionic and electropositive nature being greatest for barium (see Calcium AND CALCIUM ALLOYS Calcium compounds Strontium and STRONTIUM compounds). As size increases, hydration tendencies of the crystalline salts increase solubiUties of sulfates, nitrates, chlorides, etc, decrease (except duorides) solubiUties of haUdes in ethanol decrease thermal stabiUties of carbonates, nitrates, and peroxides increase and the rates of reaction of the metals with hydrogen increase. 

Hypobromites, the salts of hypobromous acid, do not keep well because they gradually disproportionate to bromide and bromate. Solutions are best prepared as needed from bromine and alkafl with cooling. Because disproportionation is catalyzed by cobalt, nickel, and copper (70), these impurities should be avoided. SoHd alkaline earth hypobromites, or more properly, bromide hypobromites such as calcium bromide hypobromite [67530-61 CaBr(OBr), have been known for many years, but the pure crystalline hydrates sodium hypobromite pentahydrate [13824-96-9] NaOBr 5H20, and potassium hypobromite tribydrate [13824-97-0], KOBr 3H20, were not described until 1952 (71). Hypobromites are strong bleaching agents, similar to hypochlorites. 

The alcohol sulfate salts of monovalent metals, such as sodium and potassium, crystallize as anhydrous salts from aqueous solutions, whereas salts of bivalent alkaline earth metals form hydrates with 1 mol of water less than that of the equivalent inorganic sulfate [68]. 

The azidodithiocarbonates of the alkali and alkaline earth metals are all wh, deliq crystalline compds sol in w, ale, eth or acet and insol in CSj, CC14, chlf or benz. These salts usually contain w of hydration which makes them more stable than the anhyd heavy metal salts. However, they decomp slowly at RT and rapidly on heating. They have been prepd by three methods ... 

Adducts prepared in aqueous media generally possess one or more molecules of water of hydration per molecule, the number being a function of cation, anion, and the combining ratio of carbohydrate to salt. Available data on complexes of simple carbohydrates indicate that three molecules of water per molecule may be the maximum for adducts of alkali metal salts as many as seven have been reported for those of the alkaline-earth metal salts. Most complexes, however, possess only one or two molecules per molecule. Generally, the higher the combining ratio, the smaller is the number of water molecules that can be accommodated by a molecule of the adduct. 

Adducts of alkali metal salts prepared in anhydrous alcoholic media generally retain very little alcohol of solvation after being dried under vacuum at room temperature (see Table I). The unusual ability of adducts of D-glucitol to retain alcohol is probably due largely to the great ability of D-glucitol itself to retain solvent. Adducts of alkaline-earth metal salts, however, are more strongly solvated by alcohol than adducts of alkali metal salts. For example,21 lactose CaClj 4 MeOH is relatively stable at 60° at atmospheric pressure under vacuum (< 19 mm. of Hg), a molecule releases only two of the four molecules of methanol. From aqueous alcoholic media, adducts of alkaline-earth metal salts tend to crystallize as hydrates. 

CALCIUM CHLORIDE. Calcium chloride. [CAS I004.7-52-4J. CaClj, is a white, crystalline salt that is very soluble in water. Solutions containing 30-45 wl % CaCh are used commercially. Of the alkaline-earth chlorides it is the most soluble in water, h is extremely hygroscopic and liberates large amounts of heat during water absorption and on dissolution. It forms a series of hydrates containing one. two, four, and six moles of water per mole of caJcium chloride (Table I). Another hydrate. CaCl 0.331 I O. has been identified, mol wi 116.98 94.8 wl % CaCl, heat of solution in water to infinite dilution. -71.37 kJ/mol (- 17.06 keal/mol). 

Water is the most abundant compound on earth. Seawater, which accounts for 97.3% of the world s water supply, contains 3.5 mass % of dissolved salts. Purification of drinking water involves preliminary filtration, sedimentation, sand filtration, aeration, and sterilization. Hard water, which contains appreciable concentrations of doubly charged cations such as Ca2+, Mg2+, and Fe2+, can be softened by ion exchange. Water is reduced to H2 by the alkali metals and heavier alkaline earth metals, and is oxidized to O2 by fluorine. Solid compounds that contain water are known as hydrates. 

Zn(ONH2)2.3NH2OH. This salt can. be purified by recrystallization from absolute alcohol. When partially immersed in hydrazine hydrate, and partially exposed to air, it gives off hydrogen, and forms zinc hydrazinoearboxylate dihydrazinate, (NH2.NH.CO.O)2Zn(NH2NH2)2. It does not give a precipitate with a soln. of a chloride of an alkaline earth and when the soln. is boiled, the substance is hydrolyzed, and the carbonate of the alkaline earth is precipitated. There are also indications of the formation of very unstable ferrous hydroxylamite by the action of iron on hydroxylamine salts. 

A large number of compounds used as catalysts in acid-ion lactam polymerization are known. These include alkalis, alkali-earth metals, hydrates, Grignard reagents, lithium oxide, various hydroxides and carbonates, sulfates, halides, sodium zincate, alkaline salts of different acids, i.e., compounds that cause the formation of lactam acid ion in the reactive medium. The mechanism of polymerization in the presence of sodium-lactam- salt compounds is largely known. 

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