Hexahydrated chlorides

Begin by finding the chemical formula from the name, nickel(II) chloride hexahydrate. Chloride ion carries -1 charge, and the (II) indicates that nickel is a +2 cation. Electrical neutrality requires two chlorides for every nickel. The name also tells us that the salt contains six water molecules for each unit of nickel(II) chloride. Thus, each formula unit of the salt contains one cation, two Cl anions,... 

Simple hexahydrated chlorides of Nd, Sm, Eu, Gd, Er and Pu are found to be isostructural, with octacoordinated [M(OH2)6Cl2]+ units. Complete structural analysis for monoclinic (P2/ ) [Eu(OH2)6Cl2]Cl and [Gd(OH2)6Cl2]Cl are now available 106, 107). Bel skii and Struchkov 106) proposed a highly distorted... 

Nickel forms yellow anhydrous halides NiXjlX = F. Cl. Br) and a black iodide Nil2 all these halides are made by direct combination of the elements, and the chloride by reaction of sulphur dichloride oxide with the hydrated salt. All dissolve in water to give green solutions from which the hydrates can be crystallised the solutions contain the ion [NifHjOls], and the chloride crystallises as NiCl2.6H2O, nickel(II) chloride hexahydrate. 

Mannitol, CH,0H(CH0Hi4CH40H, is a hexahydric alcohol obtained by the reduction of mannose. Since ring formation does not occur in mannitol, the hexacetyl derivative can exist in only one form, and therefore either zinc chloride or sodium acetate can be used as a catalyst for the acetylation. 

Both forms sublime very readily, even at room temperature a small sample on exposure to the air will completely volatilise in a short time, particularly on a warm day or if the sample is exposed to a gentle current of air. Hence the above method for rapid drying. A sample confined in an atmospheric desiccator over calcium chloride rapidly disappears as the vapour is adsorbed by the calcium chloride. A sample of the hexahydrate similarly confined over sodium hydroxide undergoes steady dehydration with initial liquefaction, for the m.p. of the hydrated-anhydrous mixture is below room temperature as the dehydration proceeds to completion, complete resolidification occurs. 

Pinacol possesses the unusual property of forming a crystalline hexahydrate, m.p. 45°, and the pinacol is separated in this form from the unreacted acetone and the tsopropyl alcohol. The magnciaium is conveniently amalgamated by dissolving mercuric chloride in a portion of the acetone mercury is then liberated by the reaction ... 

Iron (III) chloride hexahydrate [10025-77-17, FeCl36H2 0, is a brown-yeUow to orange material that crystallizes from a solution of iron or iron salt dissolved ia hydrochloric acid that coataias an oxidant such as Cfy or nitric acid. The monoclinic crystals contain the complex salt... 

Magnesium chloride also forms hydrates containing 8 and 12 molecules of water of hydration. The solubiUty for MgCl2 ia water is shown in Figure 2 (31) from which it can be seen that the hexahydrate is the only stable hydrate in the range of temperatures from 0 to 100°C. 

In preparation of MgCl2 from seawater, magnesium hydroxide, Mg(OH)2, is first precipitated from seawater by the addition of dolime or lime. This is then treated with hydrochloric acid to produce a neutralized magnesium chloride solution. The solution obtained is evaporated and converted into soHd magnesium chloride hexahydrate (60,61). 

Nickel chloride hexahydrate [7791-20-0] is formed by the reaction of nickel powder or nickel oxide with a hot mixture of water and HCl. Nickel duoride [13940-83-5], 4H2O, is prepared by the reaction of hydroduoric acid on nickel carbonate. Nickel bromide [18721 -96-5], NiBr2 6H20, is made... 

Aluminum Halides. AH the halogens form covalent aluminum compounds having the formula AIX. The commercially most important are the anhydrous chloride and fluoride, and aluminum chloride hexahydrate. 

Aluminum chloride hexahydrate, AIQ 6H20, manufactured from aluminum hydroxide and hydrochloric acid [7647-01-0], HQ, is used in pharmaceuticals and cosmetics as a flocculant and for impregnating textiles. Conversion of solutions of hydrated aluminum chloride with aluminum to the aluminum chlorohydroxy complexes serve as the basis of the most widely used antiperspirant ingredients (20). 

Commercially, aluminum chloride is available as the anhydrous AIQ, as the hexahydrate, AICI36 H2O, or as a 28% aqueous solution designated 32°Be. Polyalumiaum chloride, or poly(alumiaum hydroxy) chloride [1327-41 -9] is a member of the family of basic aluminum chlorides. These are partially neutralized hydrates having the formula Al2Clg (0H) 6 H2O where x = 1-5. 

The hexahydrate of aluminum chloride is a deUquescent, crystalline soHd soluble in water and alcohol and usually made by dissolving aluminum hydroxide [21645-51 -2] A1(0H)2, ia concentrated hydrochloric acid. When the acid is depleted, the solution is cooled to 0 °C and gaseous hydrogen chloride is introduced. Crystalline aluminum chloride hexahydrate, AIQ 6H20, is precipitated, filtered from the Hquor, washed with ethyl ether, and dried. 

Alternatively, anhydrous aluminum chloride may be hydroly2ed ia chilled dilute hydrochloric acid. Briquetting of the anhydrous material slows the reaction and the hydrogen chloride evolved may be recycled to aid precipitation of the hexahydrate. 

Aluminum chloride hexahydrate is available ia a 28% by weight (32° Be ) aqueous solution shipped ia glass carboys, tank cars, or tmcks. Crystalline hexahydrate is shipped ia glass containers or plastic-lined dmms. In 1980, 5200 metric tons of aluminum chloride hexahydrate on a 100% AlCl basis was produced ia the United States (10). 

The properties of calcium chloride and its hydrates are summarized in Table 1. Accurate data are now available for the heats of fusion of the hexahydrate, the incongment fusion of the tetrahydrate, and the molar heat capacities of the hexahydrate, tetrahydrate, and dihydrate (1). These data are important when considering the calcium chloride hydrates as thermal storage media. A reevaluation and extension of the phase relationships of the calcium chloride hydrates, has led to new values for the heats of infinite dilution for the dihydrate, monohydrate, 0.33-hydrate, and pure calcium chloride (1). 

These three equations represent saturation with respect to the hexahydrate, tetrahydrate, and dihydrate in the temperature ranges indicated. The phase relationships among calcium chloride, its hydrates, and a saturated solution are illustrated in the diagram in Figure 1. 

Ghromium(II) Compounds. The Cr(II) salts of nonoxidizing mineral acids are prepared by the dissolution of pure electrolytic chromium metal ia a deoxygenated solution of the acid. It is also possible to prepare the simple hydrated salts by reduction of oxygen-free, aqueous Cr(III) solutions using Zn or Zn amalgam, or electrolyticaHy (2,7,12). These methods yield a solution of the blue Cr(H2 0)g cation. The isolated salts are hydrates that are isomorphous with and compounds. Examples are chromous sulfate heptahydrate [7789-05-17, CrSO 7H20, chromous chloride hexahydrate... 

Cobalt(II) chloride hexahydrate [7791-13-1], C0CI2 6H20 is a deep red monoclinic crystalline material that deflquesces. It is prepared by reaction of hydrochloric acid with the metal, simple oxide, mixed valence oxides, carbonate, or hydroxide. A high purity cobalt chloride has also been prepared electrolyticaHy (4). The chloride is very soluble in water and alcohols. The dehydration of the hexahydrate occurs stepwise ... 

Assay, wt % Acetate tetrahydrate Carbonate Chloride hexahydrate Hydroxide Nitrate Mixed oxide Sulfate hexahydrate Sulfate feed grade... 

The most common plafing bath uses fluoride to complex the fin. A typical solution contains 45 g/L staimous chloride, 300 g/L nickel chloride hexahydrate, and 55 g/L ammonium bifluofide. It is operated at pH 2.0—2.5 usiag ammonium hydroxide temperature is 65—75°C and current about 200 A/m. The bath has excellent throwing power. Air agitation is avoided. The deposit is bright without additives. Anodes are cast nickel, and the fin is replenished by additions of staimous chloride. AHoy anodes of 72% fin have been used to a much lesser extent. Tia-nickel deposits are covered by ASTM (136) and ISO (137) specifications. One other bath based on pyrophosphate has appeared ia the Hterature, but does not seem to be ia commercial use. 

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