Magnesium salts, solubility

Table 28.6. Solubilities of calcium and magnesium salts Solubility in cold water (g/1)...

The FD C certified colors are all water-soluble dyes, but can be transformed into insoluble pigments known as lakes by precipitating the dyes with alurninum, calcium, or magnesium salts on a substrate of aluminum hydroxide. The lakes are useful in appHcations that require color whereas in dry form, such as cake mixes, or where water may be present and bleeding is a problem, such as food packaging. FD C Red Lake No. 3 was deHsted in Febmary... 

The magnesia and alumina suspension is prepared by treatment of an aqueous solution, containing aluminum and magnesium salt in the desired proportion, with sodium hydroxide. The coprecipitated aluminum and magnesium hydroxides are collected by filtration, washed free of soluble salts, and stabilized by the addition of a suitable hexatol. 

Magnesium trisihcate is a nonsystemic antacid and an adsorbent. It has a slow onset of activity and is a relatively weak antacid. It may cause diarrhea in large doses owing to soluble magnesium salts. One gram of magnesium trisihcate neutralizes 10 mL of 0.1 NUCl in 10 min, and 15 mL in 2 h. 

Magaldrate is prepared by precipitation from aqueous solutions of sodium or potassium aluminate and a magnesium salt under controlled conditions of concentration and temperature. The precipitated product is collected by filtration, washed to remove soluble by-products, and dried. 

CH2CH2) 0]2P(=0)—OH are formed from polyethoxylated nonylphenol. The magnesium salts of the ester mixture are soluble in organics and are used as dry-cleaning surfactants. 

Chemical inhibitors, when added in small amounts, reduce corrosion by affecting cathodic and/or anodic processes. A wide variety of treatments may be used, including soluble hydroxides, chromates, phosphates, silicates, carbonates, zinc salts, molybdates, nitrates, and magnesium salts. The exact amount of inhibitor to be used, once again, depends on system parameters such as temperature, flow, water chemistry, and metal composition. For these reasons, experts in water treatment acknowledge that treatment should be fine tuned for a given system. 

Magnesium salts exhibit properties similar to those of calcium, except that they generally are slightly more soluble and normally are present in MU water sources at a lower level of concentration, so that the overall scaling and deposition effect of magnesium salts is lessened. 

Further addition of lime converts soluble magnesium or sodium carbonate into the insoluble hydroxide and further insoluble calcium carbonate. In theory it is possible to limit the lime addition to maintain the magnesium salt as soluble carbonate, but in practice some magnesium hydroxide is always formed (say, 10%), so it necessary to compensate for this by the addition of more lime ... 

In spite of the good calcium and magnesium tolerance of AOS systems, situations can arise whereby too many exchangeable hardness ions present themselves to the surfactant formulation. One way to overcome this is by blending AOS with a divalent cation-tolerant surfactant. A product which has been field-tested [87] is a blend of AOS and a disulfonated alkyldiphenyloxide (DPOS). Calcium and magnesium salts of DPOS are water-soluble and remain soluble even in solutions which are very concentrated in calcium and magnesium salts. 

The difference in solubility between carbonates and hydrogen carbonates is responsible for the behavior of hard water, which is water that contains dissolved calcium and magnesium salts. Hard water originates as rainwater which dissolves carbon dioxide from the air and forms a very dilute solution of carbonic acid. 

With the reaction performance improved, attention turned to isolation of 3. The work-up of this reaction was complicated by the solubility of TH F in water and the low solubility of 3 in most organic solvents. Using extraction to remove residual magnesium salts would have severely limited volumetric productivity. We found that 3 could be isolated by quenching the reaction into aqueous HC1. Crude 3 was isolated after concentrating the organic layer. Residual TH F and magnesium salts were then removed by recrystallization from AcOH/water with less than 1% loss of 3. 

Pectins occur naturally in both soluble and insoluble forms. Soluble pectin occurs in plant juices and is particularly abundant in those juices which form jellies, such as black-currant and gooseberry. Insoluble pectins tend to occur in the green parts of plants, in fruit and in root crops.1 This insolubility is apparently due either to the presence of the pectin as its insoluble calcium or magnesium salt or because it is combined (esterified ) with cellulose or some other insoluble polysac-... 

In the laboratory, magnesium hydroxide may be prepared by double decomposition reactions by adding a soluble hydroxide to solutions of magnesium salts i.e., adding caustic soda solution to magnesium sulfate solution ... 

Unlike calcium oxide, at ordinary temperatures magnesium oxide is stable in water. There is very little formation of magnesium hydroxide. The reaction, however, is rapid at elevated temperatures. The acids form their magnesium salts which, if water-soluble, may be obtained by evaporation of the solution ... 

Boiling does not remove magnesium salts, nor CaCOs at its own solubility level, nor noncarbonate calcium (i.e., Ca2+ that is counterbalanced by Cl- or another anion of which the Ca2+ salt is freely soluble). The hardness that remains after boiling is called permanent hardness. Permanent hardness plus temporary hardness is called the total hardness. 

According to the ionic hypothesis, if the solubility product [Li]2[C0"3] is not altered, the solubility can be increased by the union of one or other of the ions of the carbonate forming complexes with the added salt. This effect is not very marked with potassium or sodium chloride or nitrate. The marked increase in the solubility with sodium and potassium sulphates is due to the formation of lithium sulphate, but with the ammonium salts soluble complexes like Li(NH3) and NH2C00 may be formed just as is the case with magnesium carbonate in the presence of ammonium salts. 

Let s say you want to produce magnesium carbonate. The chart of solubilities on page 108 tells you that MgCOj is insoluble. You should therefore be able to precipitate it from a soluble magnesium salt — the sulfate, for instance — and soluble sodium carbonate ... 

Finally, the solubilities of several lithium compounds more nearly resemble those of the corresponding magnesium salts than of other alkali metal sails. 

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