Strontium arsenates

Strontium Arsenide, Sr3As2, may be prepared by reduction of strontium arsenate. This is best accomplished by rapidly heating with carbon 10 to 1500° to 1600° C. If the heating is slow, reduction begins at about 800° C-. yielding first the arsenite, arsenic then being lost and strontium oxide formed. Calcium arsenate behaves similarly (p. 60). Strontium arsenide forms reddish-brown crystals, transparent in thin... 

As20sSr3 (s) 3SrO AS2O5 (s) Strontium Arsenate As20sSr3 (s) 3SrO AS2O5 (s)... 

Sr3(As04)2 STRONTIUM ARSENATE 1560 Ta02CI TANTALUM CHLORIDE DIOXIDE 1608... 

Arsenic species. Neutral or ammoniacal solutions of arsenate(lll) or arsenate(V) precipitate Ca ", e.g., as [Ca(H20)g]KAs04. Neutral solutions of arsenates(III) do not precipitate Sr " or Ba ". Adding NH3 precipitates part of the Sr " but not Ba " (distinction from Ca ). Aqueous arsenate(V) does not precipitate Sr " from a saturated (but still dilute) solution of SrS04 (distinction from Ca), but it does precipitate Ba as BaHAs04-H20, white, slightly soluble in H2O, soluble in acids. Strontium arsenate(V), precipitated from an alkali arsenate(V), resembles the corresponding Ba salt. 

Some elements found in body tissues have no apparent physiological role, but have not been shown to be toxic. Examples are mbidium, strontium, titanium, niobium, germanium, and lanthanum. Other elements are toxic when found in greater than trace amounts, and sometimes in trace amounts. These latter elements include arsenic, mercury, lead, cadmium, silver, zirconium, beryUium, and thallium. Numerous other elements are used in medicine in nonnutrient roles. These include lithium, bismuth, antimony, bromine, platinum, and gold (Eig. 1). The interactions of mineral nutrients with... 

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,... 

Without known nutritional function but toxic in excess Aluminum, arsenic, antimony, boron, bromine, cadmium, cesium, germanium, lead, mercury, silver, strontium... 

Heavy Metals, Vanadium, Molybdenum, Mercury, Uranium, Potassium, Calcium, Titanium, Gallium, Arsenic, Selenium, Rubidium, Strontium, Yttrium, Zirconium, Silver, Antimony, and Barium... 

Nixon277 compared atomic absorption spectroscopy, flame photometry, mass spectroscopy, and neutron activation analysis as methods for the determination of some 21 trace elements (<100 ppm) in hard dental tissue and dental plaque silver, aluminum, arsenic, gold, barium, chromium, copper, fluoride, iron, lithium, manganese, molybdenum, nickel, lead, rubidium, antimony, selenium, tin, strontium, vanadium, and zinc. Brunelle 278) also described procedures for the determination of about 20 elements in soil using a combination of atomic absorption spectroscopy and neutron activation analysis. 

Major constituents (greater than 5 mg/L) Minor constituents (O.Ol-lO.Omg/L) Selected trace constituents (less than 0.1 mg/L) Bicarbonate, calcium, carbonic acid, chloride, magnesium, silicon, sodium, sulfate Boron, carbonate, fluoride, iron, nitrate, potassium, strontium Aluminum, arsenic, barium, bromide, cadmium, chromium, cobalt, copper, gold, iodide, lead, Uthium, manganese, molybdenum, nickel, phosphate, radium, selenium, silver, tin, titanium, uranium, vanadium, zinc, zirconium... 

Admixture incompatibilities - Magnesium sulfate in solution may result in a precipitate formation when mixed with solutions containing Alcohol (in high concentrations) alkali carbonates and bicarbonates alkali hydroxides arsenates barium calcium clindamycin phosphate heavy metals hydrocortisone sodium succinate phosphates polymyxin B sulfate procaine hydrochloride salicylates strontium tartrates. 

Researchers at BNL claim that this technology may be used to extract metals such as cadmium, arsenic, lead, zinc, copper, magnesium, manganese, aluminum, barium, nickel, and chromium, as well as radionuclides such as uranium, thorium, plutonium, cobalt, cesium, and strontium. They state that the process offers the following advantages ... 

Barium Arsenide, Ba3As2.—By passing arsine over barium oxide at red heat Soubeiran 4 obtained a mixture of arsenide and arsenite. Lebeau 6 prepared the pure arsenide by reduction of barium arsenate with carbon in an electric furnace. Barium arsenide is very similar in properties to the arsenides of calcium and strontium it is slightly darker in colour, more readily fusible and more reactive chemically. Its density at 15° C. is 4-1. It burns spontaneously in fluorine, chlorine or bromine vapour. In oxygen it burns at about 300° C. and in sulphur vapour at dull red heat. 

Strontium Metarsenite, Sr(As02)2.4H20, may be obtained by the action of ammonium arsenite on a solution of a strontium salt.1 The precipitation is increased by the addition of alcohol, since the arsenite is fairly soluble in water. When dried at 100° C. it has the composition Sr(As02)2.3H20. At higher temperatures it decomposes to form strontium oxide, arsenious oxide and a little arsenic.2 Stavenhagen was unable to obtain the metarsenite in a pure state. 

Strontium Dihydrogen Orthoarsenate, Sr(H2As04)2, may be prepared 12 by adding 24 g. of strontium hydroxide to an aqueous solution of arsenic acid (containing 60 g. As2Os in 90 c.c.) and heating until a... 

The dihydrate, Sr(H2As04)2.2H20, may be obtained by treating strontium carbonate with an excess of arsenic acid.1 The crystals lose their water of crystallisation at 240° to 250° C. and on further heating yield strontium metarsenate, Sr(As03)2. 

More rarely use is made for the same purpose of other substances such as strontium and calcium chromates, lead oxychloride (Cassel yellow), lead protoxide, arsenic sulphide (orpiment), stannic sulphide (mosaic gold), potassium cobaltinitrite (cobalt yellow), etc. 

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