Solid salt solubility

C2H4N2O3, NH2CONHCOOH. Unknown in the free state as it breaks down immediately to urea and COi- The NH4, Ba, Ca, K and Na salts are known and are prepared by treating ethyl allophanate with the appropriate hydroxide. The esters with alcohols and phenols are crystalline solids, sparingly soluble in water and alcohol. They are formed by passing cyanic acid into alcohols or a solution of an alcohol or phenol in benzene. The amide of allophanic acid is biuret. Alcohols are sometimes isolated and identified by means of their allophanates. 

A) Ammonium salts. All colourless solids readily soluble in cold water. 

Sulphonic acids are frequently crystalline solids, readily soluble in water and often hygroscopic. Because of the difficulty of isolation of the free acids, they are usually encountered as the alkah metal salts. 

Acids that are solids can be purified in this way, except that distillation is replaced by repeated crystallisation (preferable from at least two different solvents such as water, alcohol or aqueous alcohol, toluene, toluene/petroleum ether or acetic acid.) Water-insoluble acids can be partially purified by dissolution in N sodium hydroxide solution and precipitation with dilute mineral acid. If the acid is required to be free from sodium ions, then it is better to dissolve the acid in hot N ammonia, heat to ca 80°, adding slightly more than an equal volume of N formic acid and allowing to cool slowly for crystallisation. Any ammonia, formic acid or ammonium formate that adhere to the acid are removed when the acid is dried in a vacuum — they are volatile. The separation and purification of naturally occurring fatty acids, based on distillation, salt solubility and low temperature crystallisation, are described by K.S.Markley (Ed.), Fatty Acids, 2nd Edn, part 3, Chap. 20, Interscience, New York, 1964. 

Digest the solid salt with aqueous NH4NCS, wash thoroughly with H2O and dry at 110° in the dark. Soluble in dilute aqueous NH3. Dissolve in strong aqueous NH4NCS solution, filter and dilute with large volume of H2O when the Ag salt separates. The solid is washed with H2O by decantation until free from NCS ions, collected, washed with H2O, EtOH and dried in an air oven at 120°. Alternatively dissolve in dilute aqueous NH3 and single crystals are formed by free evaporation of the solution in air. [J Chem Soc 836, 2405 1932 IR and Raman Acta Chem Scand 13 1607 1957 Acta Cryst 10 29 1957.]... 

In 1826 J. J. Berzelius found that acidification of solutions containing both molybdate and phosphate produced a yellow crystalline precipitate. This was the first example of a heteropolyanion and it actually contains the phos-phomolybdate ion, [PMoi204o] , which can be used in the quantitative estimation of phosphate. Since its discovery a host of other heteropolyanions have been prepared, mostly with molybdenum and tungsten but with more than 50 different heteroatoms, which include many non-metals and most transition metals — often in more than one oxidation state. Unless the heteroatom contributes to the colour, the heteropoly-molybdates and -tungstates are generally of varying shades of yellow. The free acids and the salts of small cations are extremely soluble in water but the salts of large cations such as Cs, Ba" and Pb" are usually insoluble. The solid salts are noticeably more stable thermally than are the salts of isopolyanions. Heteropoly compounds have been applied extensively as catalysts in the petrochemicals industry, as precipitants for numerous dyes with which they form lakes and, in the case of the Mo compounds, as flame retardants. 

The great importance of the solubility product concept lies in its bearing upon precipitation from solution, which is, of course, one of the important operations of quantitative analysis. The solubility product is the ultimate value which is attained by the ionic concentration product when equilibrium has been established between the solid phase of a difficultly soluble salt and the solution. If the experimental conditions are such that the ionic concentration product is different from the solubility product, then the system will attempt to adjust itself in such a manner that the ionic and solubility products are equal in value. Thus if, for a given electrolyte, the product of the concentrations of the ions in solution is arbitrarily made to exceed the solubility product, as for example by the addition of a salt with a common ion, the adjustment of the system to equilibrium results in precipitation of the solid salt, provided supersaturation conditions are excluded. If the ionic concentration product is less than the solubility product or can arbitrarily be made so, as (for example) by complex salt formation or by the formation of weak electrolytes, then a further quantity of solute can pass into solution until the solubility product is attained, or, if this is not possible, until all the solute has dissolved. 

Before Nernst had put forward his theory, Bodlander (Zeitschr. physik. Chcm., 27, 55, 1898) had been able to calculate the solubility of a salt by the measurement of its decomposition voltage, and had found that where the reaction occurring is the dissociation of a solid salt into solid uncharged atoms, the work done to split up the salt into its ions, and discharge these at the electrodes, is very nearly equal to the heat of formation. 

Up to this point, we have focused on aqueous equilibria involving proton transfer. Now we apply the same principles to the equilibrium that exists between a solid salt and its dissolved ions in a saturated solution. We can use the equilibrium constant for the dissolution of a substance to predict the solubility of a salt and to control precipitate formation. These methods are used in the laboratory to separate and analyze mixtures of salts. They also have important practical applications in municipal wastewater treatment, the extraction of minerals from seawater, the formation and loss of bones and teeth, and the global carbon cycle. 

Sometimes we have to precipitate one ion of a sparingly soluble salt. For example, heavy metal ions such as lead and mercury can be removed from municipal waste-water by precipitating them as the hydroxides. However, because the ions are in dynamic equilibrium with the solid salt, some heavy metal ions remain in solution. How can we remove more of the ions ... 

Sodium carbonate is a white, powdery solid moderately soluble in water to give a basic solution. It reacts with acids to produce a sodium salt and carbon dioxide. 

Another type of biphase partition comprises equilibration of a crown ether-containing solution with a sparingly soluble solid salt. Assuming that the amount of free salt [M+.X in (1)] at equilibrium equals the solubility—which can be determined separately—one can calculate the association constant ATlp from the amount of solubilized salt. Reinhoudt et al. (1977) applied this technique using Zeise s salts. 

Concentrations of aqueous electrolyte solutions are conventionally expressed using the aquamolality scale (L = moles salt per 55.508 mol solvent (l,000g for H20)). Some typical solubilities (298.15K) are listed in Table 5.13. Almost all salts are less soluble in D20 than in H20. For those salts whose solubility increases with temperature, which is the ordinary behaviour, the isotope effects decrease with temperature. Writing the standard state partial molar free energy of pure solid salt as Pxsalt) and its standard state in solution as p, (HorD) we have on comparing the saturated solutions in H20 and D20,... 

The solubility of an ionic solute, Sca, may be expressed in terms of its solubility product, The equilibrium between a pure solid salt, Cv+Av and its saturated solution in a solvent where it is completely dissociated to ions (generally having e > 40 see section 2.6) is governed by its standard molar Gibbs energy of dissolution... 

In this profile, the term chlorite will be used to refer to chlorite ion, which is a water-soluble ion. Chlorite ion will combine with metal ions to form solid salts, (e.g., sodium chlorite). In water, sodium chlorite is soluble and will dissolve to form chlorite ions and sodium ions. More than 80% of all chlorite (as sodium chlorite) is used to make chlorine dioxide to disinfect drinking water. Sodium chlorite is also used as a disinfectant to kill germs. 

Barium carbonate decomposes to barium oxide and carbon dioxide when heated at 1,300°C. In the presence of carbon, decomposition occurs at lower temperatures. Barium carbonate dissolves in dilute HCl and HNO3 liberating CO2. Similar reaction occurs in acetic acid. The solid salts, chloride, nitrate and acetate that are water soluble may be obtained by evaporation of the solution. Dissolution in HF, followed by evaporation to dryness, and then heating to red heat, yields barium fluoride. 

In aqueous media lutetium occurs as tripositive Lu3+ ion. All its compounds are in +3 valence state. Aqueous solutions of all its salts are colorless, while in dry form they are white crystalline solids. The soluble salts such as chloride, bromide, iodide, nitrate, sulfate and acetate form hydrates upon crystallization. The oxide, hydroxide, fluoride, carbonate, phosphate, and oxalate of the metal are insoluble in water. The metal dissolves in acids forming the corresponding salts upon evaporation of the solution and crystallization. 

Brown crystalline solid deliquesces decomposes on heating moderately soluble in water, forming a turbid solution hydrolyzes in excess water forming a brown basic salt soluble in dilute nitric acid. 

Numerous examples of solid/solid/liquid phase transfer catalysis are now known to be useful synthetically but have not been investigated mechanistically. Poly(ethylene glycol) immobilized on alumina and silica gel is active for reaction of solid potassium acetate with 1-bromobutane 184). Some of the best synthetic results with polymer supports are shown in Table 15. Often use of other solid salts or other catalysts gave poorer yields. It would be valuable to know for the design of future syntheses how these reactions depend on the partial solubility of the inorganic salts in the organic solvents and on the presence of trace amounts of water. 

The (able below contains solubility and density data lor the salts Na SQ4 and MgS()4. Express their solubilities in terms of molar concentrations, molalities and mole fractions. Calculate the contractions in volume that occur when the solutions are made from the solid salts and the solvent. Comment on the results in terms of the ell ect of ionic charges. The concentrations have been cho-.cn to be comparable. 

The salt is very soluble in water—100 grms. of cold water dissolve 16 7 parts of the salt, and 100 parts of hot water dissolve 100 parts of salt—the soln. loses ammonia when heated. J. M. Thomson and W. P. Bloxam found that the supersaturated soln. crystallizes when seeded with a crystal of the solid salt—this is taken as. showing the existence of the undissociated solid in the soln. J. M. van Bemmelen fpund that but very little ammonia can be separated by dialysis. J. Thomsen gives —10 8 Cals, for the heat of soln. of a mol. of the salt in 800 mols. of water at 18°. E. Doumer gives 0 303 for the optical refraction of the salt in dil. soln., and 45 for the mol, refraction. 

This salt is much more difficult to obtain in dry, pure form than is the corresponding sulfate. It is very soluble in water, but from concentrated solution it is deposited in crystals which in color are almost identical with those of the sulfate. Upon exposure to air, even during filtration with the pump, the crystals turn yellow through oxidation. Probably this is not due to greater ease of oxidation on the part of the solid salt but to the physical conditions that prevail. The saturated, cold solution is very viscous and sticky, and absorbent paper absorbs this liquid very slowly. Owing to the great solubility of the salt, the solution has a low vapor pressure and does not tend to evaporate in the air. Consequently, the crystals remain coated with a film of concentrated mother liquor which oxidizes very fast in the air. 

The solubility product is the equilibrium constant for the reaction in which a solid salt dissolves to give its constituent ions in solution. Solid is omitted from the equilibrium constant because it is in its standard state. Appendix F lists solubility products. 

The solubility product is the equilibrium constant for the dissolution of a solid salt into its constituent ions in aqueous solution. The common ion effect is the observation that, if one of the ions of that salt is already present in the solution, the solubility of a salt is decreased. Sometimes, we can selectively precipitate one ion from a solution containing other ions by adding a suitable counterion. At high concentration of ligand, a precipitated metal ion may redissolve by forming soluble complex ions. In a metal-ion complex, the metal is a Lewis acid (electron pair acceptor) and the ligand is a Lewis base (electron pair donor). 

Owing to reduced salt solubility, the formation of metal oxides and, eventually, the presence of stable solid-matter particles, these are all present in the SCWO processes. These particles can cause equipment-fouling and erosion. However the reduced solubility of salts under supercritical conditions introduces the possibility of a solid fluid separation. 

Halides. Indium trichloride [10025-83-8], InCl3, can be made by heating indium in excess chlorine or by chlorinating lower chlorides. It is a white crystalline solid, deliquescent, soluble in water, and has a high vapor pressure. InCl3 forms chloroindates, double salts with chlorides of alkali metals, and organic bases. 

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