Salts anhydrous

Siher I) fluoride, AgF, is prepared by evaporation of a solution of excess Ag20 in HF after filtration or by heating anhydrous AgBF. The anhydrous salt is yellow hydrates are known, It is very soluble in water and in many organic solvents. Used as a mild fluorinating agent. On treatment of a solution with Ag a sub-fluoride, Ag2F, is formed. 

These are ionic solids and can exist as the anhydrous salts (prepared by heating together sulphur with excess of the alkali metal) or as hydrates, for example Na2S.9HjO. Since hydrogen sulphide is a weak acid these salts are hydrolysed in water,... 

Other iron(If) salts include, notably the green sulphate heptahydrate FeS04.7H2O which on heating yields first the white anhydrous salt FeS04 and then decomposes ... 

On heating the pentahydrate, four molecules of water are lost fairly readily, at about 380 K and the fifth at about 600 K the anhydrous salt then obtained is white the Cu " ion is now surrounded by sulphate ions, but the d level splitting energy does not now correspond to the visible part of the spectrum, and the compound is not coloured. Copper(Il) sulphate is soluble in water the solution has a slightly acid reaction due to formation of [CufHjOijOH] species. Addition of concentrated ammonia... 

Addition of water gives the hydrated nitrate Cu(N03)2.3H2O, the product obtained when copper (or the +2 oxide or carbonate) is dissolved in nitric acid. Attempts to dehydrate the hydrated nitrate, for example by gently heating in vacuo, yield a basic nitrate, not the anhydrous salt. 

If a sample of the anhydrous salt is taken from stock, it should preferably be melted, allowed to cool, and then pulverised. 

At this point the system has throe phases (CUSO4 CuS04,Hj0 HjO vapour) and the number of components is two (anhydrous salt water). Hence by the phase rule, F + F = C + 2, t.e., 3+F = 2 + 2, or F=l. The system is consequently univariant, in other words, only one variable, e.g., temperature, need be fixed to define the system completely the pressure of water vapour in equilibrium with CUSO4 and CuS04,Hj0 should be constant at constant temperature. 

Furthermore, it is the system. Hydrate I/Hydrate II (or Anhydrous Salt), that possesses a definite pressure at a particular temperature this is independent of the relative amounts, but is dependent upon the nature of the two components in equilibrium. It is incorrect, therefore, to speak of the vapour pressure of a salt hydrate. ... 

We may now understand the nature of the change which occurs when an anhydrous salt, say copper sulphate, is shaken with a wet organic solvent, such as benzene, at about 25°. The water will first combine to form the monohydrate in accordance with equation (i), and, provided suflScient anhydrous copper sulphate is employed, the effective concentration of water in the solvent is reduced to a value equivalent to about 1 mm. of ordinary water vapour. The complete removal of water is impossible indeed, the equilibrium vapour pressures of the least hydrated tem may be taken as a rough measure of the relative efficiencies of such drying agents. If the water present is more than sufficient to convert the anhydrous copper sulphate into the monohydrate, then reaction (i) will be followed by reaction (ii), i.e., the trihydrate will be formed the water vapour then remaining will be equivalent to about 6 mm. of ordinary water vapour. Thus the monohydrate is far less effective than the anhydrous compound for the removal of water. 

Sulphonamides. Mix together 1 0 g. of the dry acid or 1 - 2 g. of the anhydrous salt with 2 5 g. of phosphorus pentachloride f and heat under a reflux condenser in an oil bath at 150° for 30 minutes. Cool the mixture, add 20 ml. of dry benzene, warm on a steam bath and stir the solid mass well to extract the sulphonyl chloride filter. Add the benzene solution slowly and with stirring to 10 ml. of concentrated ammonia solution. If the sulphonamide precipitates, separate it by filtration if no solid is obtained, evaporate the benzene on a steam bath. Wash the sulphonamide with a little cold water, and recrystallise from water, aqueous ethanol or ethanol to constant m.p. 

Names follow the lUPAC Nomenclature. Solvates are listed under the entry for the anhydrous salt. Acids are entered under Hydrogen and acid salts are entered as a subentry under hydrogen. 

Colorless crystals of iron(II) fluoride tetrahydrate [13940-89-1Fep2 4H2O, can be obtained by dissolving metallic iron or the anhydrous salt in hydrofluoric acid. The crystals of Fep2 4H2O are sparingly soluble in water and decompose to Fe202 when heated in air. 

The only reported industrial appHcation for Fep2 is its use in mst removal solutions based on oxalic acid (6). The anhydrous salt is commercially available in 100 g to 5 kg lots from Advance Research Chemicals, Aldrich Chemicals, Cerac, Johnson/Matthey, PCR, and other suppHers in the United States. As of 1993, the prices varied between 500 to 700/kg. 

The anhydrous salt is prepared by several methods, eg, by reacting ZrCl with liquid anhydrous HP. It is necessary to use an excess of HP which also acts as a wetting agent. The reaction is instantaneous and is carried out in a polyethylene jar or carboy. When the evolution of HCl ceases, the material is transferred to a tray and dried under an atmosphere of nitrogen. By proper selection of equipment, purification of raw material, and drying conditions, materials of spectrographic purity can be produced (4). 

Formates. lron(Il) formate dihydrate [13266-734], Fe(HC02)2 2H20, is a green salt which can be prepared from iron(Il) sulfate and sodium formate in an inert atmosphere. The compound is slightly soluble in water and fairly resistant to air oxidation. The anhydrous salt [3047-594] is known. 

Lithium Acetate. Lithium acetate [546-89 ] is obtained from reaction of lithium carbonate or lithium hydroxide and acetic acid. Crystalline lithium acetate dihydrate [6108-1 7a(/, CH2C02Li 2H20, melts congmentiy in its own water of crystallization at 57.8°C. The anhydrous salt [646-89-4] melts... 

Lithium Borates. Lithium metaborate [13453-69-5], LLBO2 2H20, is prepared from reaction of lithium hydroxide and boric acid. It is used as the fluxing agent for the matrix for x-ray fluorescence analytical techniques and in specialty glasses and enamels. The anhydrous salt melts at 847°C. 

The salt is extremely hydroscopic and is used in dehumidification appHcations. It is very soluble in water (Table 4). The hydrates LiCl 2H20 [16712-19-9] and LiCl H2O [16712-20-2] precipitate at temperatures below 100°C. The anhydrous salt precipitates at 100°C. The salt has appreciable solubiHty in alcohols and amines. 

Lithium Bromide. Lithium biomide [7550-35-8] LiBi, is piepaied from hydiobiomic acid and lithium carbonate oi lithium hydroxide. The anhydrous salt melts at 550°C and bods at 1310°C. Lithium bromide is a component of the low melting eutectic electrolytes ia high temperature lithium batteries. 

The salt is extremely soluble ia water (Table 4), crystallising from aqueous solution as the hydrates LiBr H20 [23303-71-17, LiBr 2H20 [13453-70-8] and LiBr 3H2O [76082-04-7]. The anhydrous salt is obtained by dryiag under vacuum at elevated temperatures. 

Lithium Iodide. Lithium iodide [10377-51 -2/, Lil, is the most difficult lithium halide to prepare and has few appHcations. Aqueous solutions of the salt can be prepared by carehil neutralization of hydroiodic acid with lithium carbonate or lithium hydroxide. Concentration of the aqueous solution leads successively to the trihydrate [7790-22-9] dihydrate [17023-25-5] and monohydrate [17023-24 ] which melt congmendy at 75, 79, and 130°C, respectively. The anhydrous salt can be obtained by carehil removal of water under vacuum, but because of the strong tendency to oxidize and eliminate iodine which occurs on heating the salt ia air, it is often prepared from reactions of lithium metal or lithium hydride with iodine ia organic solvents. The salt is extremely soluble ia water (62.6 wt % at 25°C) (59) and the solutions have extremely low vapor pressures (60). Lithium iodide is used as an electrolyte ia selected lithium battery appHcations, where it is formed in situ from reaction of lithium metal with iodine. It can also be a component of low melting molten salts and as a catalyst ia aldol condensations. 

There are a number of complex chlorides of three general types M(MnCl2), M2(MnCl, and M4(MnClg). M is monovalent in each case. Fluorine forms only 9M(MnF.) and the only complex bromine compound reported is Ca(MnBt 4H2O. There are no iodide complexes. The anhydrous salt, MnCl2, forms cubic pink crystals, and three well-defined hydrates exist. Aqueous solubiUties of the tetrahydrate and dihydrate ate given in Table 7. 

Manganese Nitrate. Manganese nitrate [10377-66-9] is prepared from manganese(II) oxide or carbonate using dilute nitric acid, or from Mn02 and amixture of nitrous and nitric acids. Mn(N02)2 exists as the anhydrous salt [10377-66-9]-, the monohydrate [3228-81-9]-, ttihydrate [55802-19-2],... 

Properties. Nickel forms anhydrous as well as hydrated haHdes. The properties of the anhydrous salts are given in Table 1. 

Potassium Oxalate. The monohydrate [6487-48-5] K2C204-H20, mol wt 184.24, is produced as a colodess crystalline material or a white powder. The anhydrous salt [583-52-8] mol wt 166.22, is obtained when the monohydrate is dehydrated at 160°C. The monohydrate is preferred as a reagent in analytical chemistry and in miscellaneous uses principally because of its high solubihty as compared with other simple neutral oxalates the saturated solution, at 0°C, contains about 20 wt %, and at 20°C, about 25 wt %... 

Ammonium perchlorate is a colorless, crystalline compound having a density of 1.95 g/mL and a molecular weight of 117.5. It is prepared by a double displacement reaction between sodium perchlorate and ammonium chloride, and is crystallized from water as the anhydrous salt. 

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