Sodium tellurate

Sodium tellurate (Na2Te04) exhibits similar oxidizing properties towards thiols. 

The roasted pellets or extmdes are ground and leached in water. The hexavalent selenium dissolves as sodium selenate [13410-01 -0]> Na2Se04. Sodium tellurate, being highly insoluble in the now very strongly alkaline solution, remains in the residue. The separation between selenium and tellurium is readily achieved, provided all tellurium is oxidized to the hexavalent state. 

Sodium tellurate [10101 -25-8], N TeO (53.7% Te theoretically), is made by oxidizing sodium tellurite solution with hydrogen peroxide. The reaction is exothermic. 

Metal Coatings. Tellurium chlorides, as well as tellurium dioxide in hydrochloric acid solution, impart permanent and attractive black antique finish to silverware, aluminum, and brass. Anodized aluminum is colored dark gold by tellurium electro deposition. A solution containing sodium tellurate and copper ions forms a black or blue-black coating on ferrous and nonferrous metals and alloys. Addition of sodium tellurite improves the corrosion resistance of electroplated nickel. Tellurium diethyldithiocarbamate is an additive in bright copper electroplating (see Electroplating). 

With sodium thiosulphate the arsenite forms oxythioarsenates (see p. 282), as it also does with tri- and tetra-thionates sodium dithionate does not react either in cold or boiling solution. Sodium tellurate causes oxidation to arsenate.1 An ammoniacal solution of silver azide is reduced to silver by sodium arsenite other metallic azides do not react. 

Reactions of tellurates To study these reactions use a (Mm solution of sodium tellurate, Na2Te04. 

Sodium tellurate (01m). Dissolve 27-4 g sodium tellurate dihydrate, Na2Te04.2H20, in water and dilute to 1 litre. 

Sodium tellurate,1 Na2Te04,2H20.—The tellurate is prepared in a similar manner to the selenate.2 It is not readily soluble, and undergoes reduction easily to tellurium.3 It is only known in the form of dihydrate. 

SYNS SODIUM TELLURATE(IV) TELLURIC ACID, DISODIUM SAI.T TELLUROUS ACID, DISODIUM SALT... 

Add 1 mg each of carriers for tin (as sodium stannate. . antimony (as potassium antimonyl tartrate), tellurium (as sodium tellurate), and molybdenum (as ammonium molybdate), and dry under the lamp. Add 0.1 g of potassium hydroxide and heat carefully over a burner until a tranquil melt is. obtained. Raise the temperature to a dull red heat and maintain at this temperature for 5 minutes, keeping the melt swirled the whole time. 

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