Calcium and strontium hydroxides

In 1815, L. G. Gilbert1 noticed that thoroughly dried calcium oxide or hydroxide does not react chemically with dry chlorine, and similarly, in 1879, J. K. Weisherg showed that the same remark applies to dry barium or strontium oxide. The case is very different if moisture he present. With barium hydroxide two gram-atoms of chlorine are absorbed per gram-atom of the bivalent barium, and barium chloride and chlorate are produced so that if barium hypochlorite is formed as the first product of the reaction, it is immediately decomposed 3Ba(0Cl)2=Ba(C103)2 +2BaCl2 with calcium and strontium hydroxides, the reaction appears to he much... 

Oxo-acids. a) Both D-glucuronic (LXX) andD-galacturonic (LXXII) acids are converted to the 5-oxo-L-aldonic acids (LXXI, LXXIII) by the carefully controlled action of calcium and strontium hydroxides . ... 

Compared to the hydroxides of calcium and strontiuim, barium hydroxide is the most water-soluble and also the strongest base. Additionally, barium hydroxide is more difficult to convert to the oxide by heating than are the corresponding hydroxides of calcium and strontium. Barium oxide is more readily converted to the peroxide than are the oxides of the other alkaline earths. 

Heating with the following solids, their fusions, or vapours (a) oxides, peroxides, hydroxides, nitrates, nitrites, sulphides, cyanides, hexacyano-ferrate(III), and hexacyanoferrate(II) of the alkali and alkaline-earth metals (except oxides and hydroxides of calcium and strontium) (b) molten lead, silver, copper, zinc, bismuth, tin, or gold, or mixtures which form these metals upon reduction (c) phosphorus, arsenic, antimony, or silicon, or mixtures which form these elements upon reduction, particularly phosphates, arsenates,... 

Fine powdered strontium combusts spontaneously in air. It reacts more violently with water than calcium and produces hydrogen and strontium hydroxide. 

Complexes of alkali metals and alkaline-earth metals with carbohydrates have been reviewed in this Series,134 and the interaction of alkaline-earth metals with maltose has been described.135 Standard procedures for the preparation of adducts of D-glucose and maltose with the hydroxides of barium, calcium, and strontium have been established. The medium most suitable for the preparation of the adduct was found to be 80% methanol. It is of interest that the composition of the adducts, from D-glucose, maltose, sucrose, and a,a-trehalose was the same, namely, 1 1, in all cases. The value of such complex-forming reactions in the recovery of metals from industrial wastes has been recognized. Metal hydroxide-sugar complexes may also play an important biological role in the transport of metal hydroxides across cell membranes. 

How can the oxides, peroxides, and hydroxides of the alkaline-earth metals be prepared What are the commercial names of calcium and barium hydroxide solutions How do the solubility, basic properties, and thermal stability of the hydroxides change in the series calcium-strontium-barium ... 

With the exception of beryllium, the alkaline earth elements react with water to yield metal hydroxides, M(OH)2. Magnesium undergoes reaction only at temperatures above 100°C calcium and strontium react slowly with liquid water at room temperature. Only barium reacts vigorously. 

Nitric acid is usually monobasic, forming a series of salts, the nitrates. The basic salts have been discussed by A. Ditte,11 E. Groschuff, and others—see, for example, the basic lead nitrates. The nitrates are usually made by the action of the acid on the metal, hydroxide, oxide, carbonate, etc. According to H. Braconnot, the cone, acid does not decompose dehydrated sodium, barium, calcium, or lead carbonate, even when boiling, because the nitrates of these bases are insoluble in the cone, acid, and a surface film of nitrate protects the remainder of the carbonate from the acid. Potassium carbonate is decomposed by the cone, acid because the nitrate is soluble in the cone. acid. J. Pelouze said that an alcoholic soln. of nitric acid does not act on potassium carbonate, but it acts slowly on sodium, barium, and magnesium carbonates, and rapidly on calcium and strontium carbonates because, added H. Braconnot, calcium and strontium nitrates are readily dissolved by alcohol, whereas potassium nitrate is but sparingly soluble in that menstruum. Potassium hydroxide resists attack by a soln. of nitric acid in ether unless the mixture is boiled or shaken. A. A. Kazantzeff discussed the influence of nitric acid on the solubilities of the nitrates. 

Most hydroxide compounds are insoluble, except alkali metal hydroxides and barium hydroxide [Ba(OH)2], which are soluble, and calcium hydroxide [Ca(OH)2] and strontium hydroxide [Sr(OH) 2], which are slightly soluble. 

The sample is mixed and heated to 80-90 °C on a magnetic stirrer. Then precipitation of calcium and strontium phosphates in alkaline medium (pH = 8 - 9) is performed by adding concentrated ammonium hydroxide. Precipitate is allowed to settle for at least 2 hours to one night. Then the supernatant is discarded. The precipitate is collected in a centrifuge tube and rinsed with alkalized water. Precipitate is dried in a warm atmosphere at 80°C. 

The extraction of transuranic elements has been made by co-precipi-tation in several ways (5,6). We use either one of two methods, depending on what other nuclides are also sought in the sample. The first method is co-precipitation with 0.5-1.0 g iron as hydroxide at pH 9-10 using ammonium hydroxide while the second method is co-precipitation with calcium and strontium oxalate at pH 5-6 using oxalic acid. There are about 22 g calcium and 0.44 g strontium in 55 1. of open-ocean seawater. Because Sr is usually measured in the same seawater sample, we normally add 2 g strontium to that which is naturally present. 

The process for subsequent extraction of alkali earth elements from mineralized effluents rom the iodine-txomine production in Turkmenistan includes the investigation of the possibility of isolating calcium and strontium from sodium hydroxide solutions. 

Evzhanov, Kh Andiyasova, G.I., and Beikelieva, L.K., Conditions of the isolation of calcium and strontium with sodium hydroxide in the high mineralized chloride based waters . Chemistry and Water Technology, 1986, (4), 36-38. 

A more common type of spectral interference in either emission or absorption measurements arises from the occurrence of band emission-spectra due to molecular species in the flame. (In fact, many elements can be measured by means of the band spectra of the molecules they form in certain flames.) Calcium and strontium, for example, exist partially as molecular hydroxides and oxides in a flame and emit bands in the vicinity of both the sodium and lithium resonance lines. When the alkaline-earth/alkali-metal ratio is high, the interference can become serious, unless a high-resolution monochromator is used. 

Depilatories epitomize the chemical destruction of hair and allow hair removal by scraping with a blunt instmment or by rubbing with terry cloth. Chemical depilatories are based on 5-6% calcium thioglycolate in a cream base (to avoid runoff) at a pH of about 12. The pH is maintained with calcium or strontium hydroxide. Hair destraction is rapid, requiring not more than about 10 min. Treatment with a depilatory is followed by careful rinsing with water and various conditioning products intended to restore the skin s pH to normal. This type of treatment does not destroy the dermal papilla, and the hair grows back. 

In spite of widespread usage of these compounds, the stmctures of only the calcium, barium, and strontium compounds are reasonably weU-estabhshed. The materials are generally made by trituratiag the oxides, or hydroxides, with aqueous hydrogen peroxide and dryiag the soHd products. The commercial products are typically mixtures of the peroxides with varyiag amounts of hydroxides, oxides, carbonates, hydrates, and peroxohydrates. 

Strontium [7440-24-6] Sr, is in Group 2 (IIA) of the Periodic Table, between calcium and barium. These three elements are called alkaline-earth metals because the chemical properties of the oxides fall between the hydroxides of alkaU metals, ie, sodium and potassium, and the oxides of earth metals, ie, magnesium, aluminum, and iron. Strontium was identified in the 1790s (1). The metal was first produced in 1808 in the form of a mercury amalgam. A few grams of the metal was produced in 1860—1861 by electrolysis of strontium chloride [10476-85-4]. 

Resoles are usually those phenolics made under alkaline conditions with an excess of aldehyde. The name denotes a phenol alcohol, which is the dominant species in most resoles. The most common catalyst is sodium hydroxide, though lithium, potassium, magnesium, calcium, strontium, and barium hydroxides or oxides are also frequently used. Amine catalysis is also common. Occasionally, a Lewis acid salt, such as zinc acetate or tin chloride will be used to achieve some special property. Due to inclusion of excess aldehyde, resoles are capable of curing without addition of methylene donors. Although cure accelerators are available, it is common to cure resoles by application of heat alone. 

The equivalent of a base is that mass of it which contains one replaceable hydroxyl group, i.e. 17.008 g of ionisable hydroxyl 17.008 g of hydroxyl are equivalent to 1.008 g of hydrogen. The equivalents of sodium hydroxide and potassium hydroxide are the mole, of calcium hydroxide, strontium hydroxide, and barium hydroxide half a mole. 

The presence of normal concentrations of sodium, magnesium, and strontium have no net effect on the determination of calcium above the approximate level of accuracy of about 0.1% so that no correction factor seems necessary. A sufficient amount of titrant must be added to complex at least 98% of dissolved calcium before the buffer is added this apparently reduces the loss of calcium by coprecipitation with magnesium hydroxide. 

There are a number of interferences that can occur in atomic absorption and other flame spectroscopic methods. Anything that decreases the number of neutral atoms in the flame will decrease the absorption signal. Chemical interference is the most commonly encountered example of depression of the absorption signal. Here, the element of interest reacts with an anion in solution or with a gas in the flame to produce a stable compound in the flame. For example, calcium, in the presence of phosphate, will form the stable pyrophosphate molecule. Refractory elements will combine with 0 or OH radicals in the flame to produce stable monoxides and hydroxides. Fortunately, most of these chemical interferences can be avoided by adding an appropriate reagent or by using a hotter flame. The phosphate interferences, for example, can be eliminated by adding 1 % strontium chloride or lanthanum chloride to the solution. The strontium or lanthanum preferentially combines with the phosphate to prevent its reaction with the calcium. Or, EDTA can be added to complex the calcium and prevent its combination with the phosphate. 

Alkali metal (Group IA) hydroxides (LiOH, NaOH, KOH, RbOH and CsOH) Calcium, strontium, and barium hydroxides... 

---