Sodium compounds tungstate

The metals (Li, Na, K) as well as the tungstates and hydroxides (which form during reduction) are liquid at the usual temperatures. No evaporation occurs below 800 °C but, above 800 °C, a partial or total evaporation takes place, depending on the respective element and the nature of the compound (tungstate, hydroxide, silicate, borate, etc.). Lithium as Li3B03, for example, or sodium as silicate are less volatile than LiOH or NaOH. In contrast to Na and K, Li cannot be volatilized due to its high boiling point. 

A considerable difference in the toxicity of soluble and insoluble compounds of tungsten has been reported (58). For soluble sodium tungstate,... 

Orally in rats, the toxicity of sodium tungstate was highest, tungsten trioxide was intermediate, and ammonium tungstate [15855-70-6] lowest (59,60). In view of the degree of systemic toxicity of soluble compounds of tungsten, a threshold limit of 1 mg of tungsten per m of air is recommended. 

The Falin-Ciocalteu reagent (FCR) is a complex formed in a reaction between sodium tungstate and sodium molybdenate in hydrochloric add and phosphoric acid, which turns yellow after lithium sulphate is added. The reagent reads in an alkaline environment with reducing compounds. Such a reaction gives a blue chromophore which is observed by colorimetry. The Folin-Ciocalteu method is highly sensitive - both to phenolic and non-phenolic compounds, e.g. proteins, vitamin C, vitamin Bj, folic acid, Cu(I). The method is applied most frequently to determine the total content of phenolic compounds [34,35]. If that is the case, a sample for determination should be prepared in a proper manner to minimise the effect of non-phenolic... 

According to C. F. Barwald and A. Monheim (1835), the decomposition is accelerated by the presence of organic substances. J. Milbauer tried the effect of thirty-two metal chlorides of sodium tungstate and molybdate of uranyl sulphate and of sulphuric, selenic, arsenic, and boric acids on the photo-decomposition of chlorine water, and found. that none accelerated but that most retarded the action. Chlorine catalyzes the decomposition of bromine water and bromine, chlorine water while iodine does not accelerate, but rather retards the reaction, probably by forming relatively stable iodine compounds. A. Bcnrath and H. Tuchel found the temp, coeff. of the velocity of the reaction with chlorine water between 5° and 30° increases in the ratio 1 1 395 per 10°. 

Thiosalts and Sulphides of Molybdenum and Tungsten. Pour 2-3 ml of an ammonium molybdate solution into one test tube and 2-3 ml of a sodium tungstate solution into another one. Add 2-3 drops of a 25 % ammonia solution to each solution and pass a stream of hydrogen sulphide through them from a Kipp gas generator. What compounds form Acidify the solutions with a 10% hydrochloric... 

Reduction of MoIybdenum(VI) and Tungsten VI) Compounds. Pour 3 ml of an ammonium molybdate solution into each of four test tubes, acidify with a 2 N hydrochloric acid solution, and heat up to boiling. Add solutions of sulphuric acid, hydrogen sulphide, and tin(Il) chloride to three of the tubes, respectively, and throw one or two small pieces of zinc into the last tube. Perform similar experiments using sodium tungstate as the initial reactant. Write the equations of the reactions. 

Molybdenum and Tungsten Peroxide Compounds. Pour ammonium molybdate and sodium tungstate solutions into separate test tubes, acidify them with sulphuric acid, and add several drops of a 1 % hydrogen peroxide solution to each tube. How does the colour of the solutions change Write the equations of the reactions. 

Gravimetric Methods.—The vanadium compound is converted into sodium vanadate by fusion or other method, and after separation from other salts (e.g. arsenate, molybdate, phosphate, chromate, tungstate) is precipitated from nearly neutral solution either as (a) mercurous vanadate or (b) basic lead vanadate. In (a), mercurous... 

Trichloroisopropoxytitanium, 300 Trichloromethyltitanium, 216 Triisopropoxymethyltitanium, 213 Triisopropoxy[ l-(trimethylsilyl)-l, 2-bu-tadienyljtitanium, 218 Tungsten Compounds /rans-Bromotetracarbonyl(methyl-methylidyne)tungsten, 49 Hydrogen peroxide-Sodium tungstate, 145... 

Sodium tungstate, 145 Tungsten carbonyl, 49 Vanadium Compounds Alkynylvanadium(III) chloride,... 

Restriction of the molybdenum intake by young rats in a synthetic purified casein diet results in a decreased level of tissue, particularly small intestinal, xanthine oxidase. The enzyme levels arc rest tired to normal by the inclusion of sodium molybdate and other molybdate compounds. Sodium tungstate is a competitive inhibitor of molybdate, and dietary intakes of tungstate greatly reduce the molybdenum and xanthine oxidase concentrations in tissues. 

Sodium tungstate loses both water molecules at 110°C. The water is not rapidly regained, but the compound should be kept in a desiccator after drying and should be weighed quickly once it is removed. 

A hydrosol of tungsten hydroxide is readily produced by the electrolysis of a 2 per cent, solution of sodium tungstate between a mercuiy cathode and a silver anode in a Hildebrand cell. The solution must not be allow ed to become acid, or blue compounds are produced. The hydrosols obtained in this way are clear and transj arent but brown in colour. The addition of potassium chloride causes coagulation, a black powder, resembling the lower oxides of tungsten, being formed. ... 

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