Partially soluble salts

Figure 5.17 The solubility s of a partially soluble salt is related to the equilibrium constant (partition) and obeys the van t Hoff isochore, so a plot of In s (as y ) against 1 IT (as x ) should be linear, with a slope of AF lution -t- R . Note how the temperature is expressed in kelvin a graph drawn with temperatures expressed in Celsius would have produced a curved plot. The label KIT on the x-axis comes from l/T -t- 1/K...

An additional point worth mentioning is that the potentiometric method can monitor several partially soluble salts at once. For example, if a solution contains chloride, bromide and iodide ions, then a plot of emf against the volume of cation (e.g. Ag ) will contain three inflection points (see Figure 4.8), one for each of the three silver halides. for Agl is smaller than that for AgCl, while (AgBr) has an intermediate value, so the first inflection point represents the precipitation of Agl, the second represents formation of AgBr and the third represents the formation of insoluble AgCl. ... 

Figure 7.18 Ternary diagram for two partially soluble salts (a, /3, sharing a common ion) and solvent (C), illustrating the common-ion effect of one salt influencing the solubility of the other. (The plotted behavior corresponds to the N Cl/iNFL SC /lLO system.)...

Several different subscripts are used with the equilibrium constant When all reactants or products that appear in the equilibrium expression are gases, and pressures are used instead of molarity, the symbol for the equilibrium constant is Kp. If weak acids and bases are under investigation, the equilibrium constant symbol is written as K or K,. When the equilibrium constant refers to the autoionization of water, the symbol K, is used. Solubility product equilibria express the ion concentrations of partially soluble salts. The equilibrium constant symbol K p is used for solubility product equilibria. ... 

Cobalt(Il) dicobalt(Ill) tetroxide [1308-06-17, Co O, is a black cubic crystalline material containing about 72% cobalt. It is prepared by oxidation of cobalt metal at temperatures below 900°C or by pyrolysis in air of cobalt salts, usually the nitrate or chloride. The mixed valence oxide is insoluble in water and organic solvents and only partially soluble in mineral acids. Complete solubiUty can be effected by dissolution in acids under reducing conditions. It is used in enamels, semiconductors, and grinding wheels. Both oxides adsorb molecular oxygen at room temperatures. 

Calcium hexacyanoferrate (II) (IIH2O) [ 13821 -08-4] M 490.3. Recrystd three times from conductivity H2O and air dried to constant weight over partially dehydrated salt. [Trans Faraday Soc 45 855 1949.] Alternatively the Ca salt can be purified by pptn with absolute EtOH in the cold (to avoid oxidation) from an air-free saturated aqueous soln. The pure lemon yellow crystals are centrifuged, dried in a vacuum desiccator first over dry charcoal for 24h, then over partly dehydrated salt and stored in a dark glass stoppered bottle. No deterioration occurred after 18 months. No trace of Na, K or NH4 ions could be detected in the salt from the residue after decomposition of the salt with cone H2SO4. Analyses indicate 1 Imols of H2O per mol of salt. The solubility in H2O is 36.45g (24.9 ) and 64.7g (44.7 ) per lOOg of solution. [J Chem Soc 50 1926.]... 

The oxidation products are almost insoluble and lead to the formation of protective films. They promote aeration cells if these products do not cover the metal surface uniformly. Ions of soluble salts play an important role in these cells. In the schematic diagram in Fig. 4-1 it is assumed that from the start the two corrosion partial reactions are taking place at two entirely separate locations. This process must quickly come to a complete standstill if soluble salts are absent, because otherwise the ions produced according to Eqs. (2-21) and (2-17) would form a local space charge. Corrosion in salt-free water is only possible if the two partial reactions are not spatially separated, but occur at the same place with equivalent current densities. The reaction products then react according to Eq. (4-2) and in the subsequent reactions (4-3a) and (4-3b) to form protective films. Similar behavior occurs in salt-free sandy soils. 

Neutralized sulfonated asphalt (i.e., salts of sulfonated asphalt and their blends with materials such as Gilsonite, blown asphalt, lignite, and mixtures of the latter compounds) are commonly used as additives in drilling fluids. These additives, however, cause some foaming in water or water-based fluids. Furthermore, these additives are only partially soluble in the fluids. Therefore, liquid additives have been developed to overcome some of the problems associated with the use of dry additives. On the other hand, with liquid compositions containing polyglycols, stability problems can arise. Stable compositions can be obtained by special methods of preparation [1407]. In particular first the viscosifier is mixed with water, then the polyglycol, and finally the sulfonated asphalt is added. 

Electrodes of the second kind. These electrodes consist of three phases. The metal is covered by a layer of its sparingly soluble salt, usually with the character of a solid electrolyte, and is immersed in a solution containing the anions of this salt. The solution contains a soluble salt of this anion. Because of the two interfaces, equilibrium is established between the metal atoms and the anions in solution through two partial equilibria between the metal and its cation in the sparingly soluble salt and between the anion in the solid phase of the sparingly soluble salt and the anion in solution (see Eqs (3.1.24), (3.1.26) and (3.1.64)). 

We incorporate an ammonium salt to immobilize the Zn2+ ions NH4CI is prepared as a paste, and forms a partially soluble complex with zinc cations produced at the... 

Pulping additives such as quinoid compounds increase the yield of the pulp mass up to 4% [128]. For commercial application the most promising additives are anthraquinone (AQ) or the more convenient soluble salt of tetrahydroan-thraquinone (THAQ). If AQ or THAQ could be obtained at a price below 2/kg it would find a substantial market as a pulping additive [129], Commercial production of THAQ is now based on the partial thermochemical oxidation of naphthalene. In recent years, however, the lure of the pulp market has promoted several attempts to develop a process for the electrosynthesis of THAQ based on the indirect electrooxidation of naphthalene to naphthaquinone (NQ) with Ce4+, according to the stoichiometry of the reactions 1, 2 and 3. 

Species such as HCl that completely ionize in water are called strong electrolytes, and those that only partially ionize are called weak electrolytes. Most soluble salts also fall into the strong electrolyte category. 

The results obtained with ISEs have been compared several times with those of other methods. When the determination of calcium using the Orion SS-20 analyser was tested, it was found that the results in heparinized whole blood and serum were sufficiently precise and subject to negligible interference from K and Mg ([82]), but that it is necessary to correct for the sodium error, as the ionic strength is adjusted with a sodium salt [82], and that a systematic error appears in the presence of colloids and cells due to complexa-tion and variations in the liquid-junction potential [76]. Determination of sodium and potassium with ISEs is comparable with flame photometric estimation [39, 113, 116] or is even more precise [165], but the values obtained with ISEs in serum are somewhat higher than those from flame photometry and most others methods [3, 25, 27, 113, 116]. This phenomenon is called pseudohyponatremia. It is caused by the fact that the samples are not diluted in ISE measurement, whereas in other methods dilution occurs before and during the measurement. On dilution, part of the water in serum is replaced by lipids and partially soluble serum proteins in samples with abnormally increased level of lipids and/or proteins. 

Chromium(II) perchlorate is the salt of choice for preparing the en complex in dimethylformamide solution. At comparable concentration levels chromium(II) sulfate is insoluble, and the <-.lu-omium(lI) chloride - is only partially soluble in the i-( a< tion solution. 

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. 

Hexaethylenediamino-hexol-tetrachromic Sulphate, [Cr4(OH)6en6](SO4)3.10H2O, is prepared from partially dehydrated chromic alum. The bluish-grey powder obtained is heated with ethylene-diamine monohydrate on a water-bath till a red-coloured mass is produced, which consists of a mixture of potassium sulphate, luteo-chromic sulphate, and the sulphate of the hexol compound, and from the mixture the latter compound is obtained by dissolving out the more soluble salts with water. The crude, difficultly soluble sulphate is purified by dissolving in dilute sulphuric acid and reprecipitating with excess of ammonia. It crystallises in small needles which are almost insoluble in water and soluble in dilute acids. 

Cobaltocenium tetrak/s(tetracarbonylcobaltio)bismuthate( — 1), [Cp2Co]-[Bi Co(CO)4 4], is a reddish-brown solid which must be stored under nitrogen.8 The [Me4N]+ salt has been isolated and structurally characterized.9 The Cp2Co+ salt is insoluble in hexane, toluene, and only partially soluble in diethyl ether. It dissolves in CH2C12, MeOH, acetone, MeCN, and THF. IR (CH2C12, cm-1) 2066(m), 2028(vs), 1969(s), and 1890(w). 

The weathering of surface rocks has had a critical role in the chemical evolution of the continental crust for most of the Earth s history. In the presence of air and water, mafic minerals tend to rapidly weather into iron (oxy)(hydr)oxides, clays, and other silicate minerals, and at least partially water-soluble salts of alkalis (sodium and potassium) and alkaline earths (calcium and magnesium). In contrast, quartz in felsic and intermediate igneous rocks is very stable in the presence of surface air and water, which explains why the mineral readily accumulates in sands and other sediments. 

In an actual procedure, the carboxylic acid is reacted with an optically active a-methylbenzylamine to crystallize out the less-soluble salt in the quantities of about 50% of the whole diastereomeric salts. The double decompositions of both salts existing in the precipitate and mother liquor give the dicarboxylic acids of (+) and ( ) 60% ee, respectively. When these partially resolved carboxylic acids are recrystallized from water, the precipitated crystals are almost racemic, and the carboxylic acids of 88% ee remain in water. They can be converted into the corresponding acid anhydrides by the action of acetyl chloride. Acid anhydrides of almost 100% ee can be obtained by the recrystallization from acetone, after recovering the active acids from the mother liquor. Optically pure (+)- and (-)- ra .S -l,2-cyclohcxancdicarboxylic acids can be obtained by the hydrolysis of these anhydrides. 

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