Selenic acid, crystalline

Samarium (III) nitrate, analysis of anhydrous, 6 41 Selenic acid, crystalline, 3 137 Selenides, precipitation of pure metallic, from solutions of hydrogen selenide, 2 185 Selenium, red and gray, 1 119 Selenium (II) chloride, formation of, by selenium(IV) chloride, 6 127... 

Selenium trioxide, SeO, is white, crystalline, and hygroscopic. It can be prepared by the action of sulfur trioxide on potassium selenate or of phosphorous pentoxide on selenic acid. It forms selenic acid when dissolved in water. The pure trioxide is soluble in a number of organic solvents. A solution in Hquid sulfur dioxide is a selenonating agent. It is stable in very dry atmospheres at room temperature and on heating it decomposes first to selenium pentoxide [12293-89-9] and then to selenium dioxide. 

When selenic acid and molybdic acid are heated together on a water-bath for several days a compound of composition Mo03.Se03 is formed, which is obtainable as a crystalline mass,4 and which with a little water yields a hydrate, having the formula Mo03.Se03.2H20 when dried at 110° C. This compound has the properties of a tetrabasic acid. 

Selenium is a steel gray or purplish powder, also fabricated into pellets, sticks, or plates. Selenium dioxide, selenous acid, and the alkali-metal selenites and selenates are colorless powders or crystals. Selenium chloride (reddish yellow), selenyl chloride (colorless or yellow) (bp, 176°C), and selenic acid (colorless) are liquids, whereas selenium tetrachloride is a cream-colored crystalline solid.1... 

This is very different from sulfuric and selenic acids. It consists of hydrogen-bonded octahedral molecules Te(OH)6 in both its cubic and monoclinic crystalline forms. The acid or its salts may be prepared by oxidation of tellurium or Te02 by H202,... 

Calculate the concentrations of H3O+, OH-, HSe04-, and Se04 - in 0.12 M H2Se04, selenic acid, solution. Some kidney stones are crystalline deposits of calcium oxalate, a salt of oxalic acid, (COOH)2. Calculate the concentrations of H3O+, OH-, COOCOOH-, and (C0Q-)2 in 0.12 M (COOH)2. Compare the concentrations with those obtained in Exercise 62. How can you explain the difference between the concentrations of... 

Selivanova, Zubova, and Finkel stein [59SEL/ZUB] prepared the salt from silver nitrate and selenic acid. The product was shown to be crystalline by X-ray diffraction. The solubility product of... 

Ag2Se04 was prepared by mixing stoichiometric quantities of silver nitrate and selenic acid. The salt contained 60.04% Ag which is close to the theoretical value of 60.14%. The preparation was shown to be crystalline by X-ray diffraction. The solubility was measured after 15 to 20 days in a thermostat. No increase in solubility was observed between day 15 and day 20. The silver concentration was determined by a tur-bidimetric method. 

The heat of precipitation silver selenate was measured by mixing 0.04241 moles of silver nitrate dissolved in 325 g of water with 0.02122 moles of selenic acid in an isothermal calorimeter equipped with a sensitive thermometer. The acid (7.07 M) was contained initially in a bulb that was broken in order to start the reaction. The Ag2Se04 formed was shown to be crystalline by X-ray diffraction. The water equivalent was determined after each run. The experimental results and the evaluation of the standard enthalpy of formation of Ag2Se04(cr) are shown in Table A-17. 

The solubility of SrSe04(cr) in water has been determined over the temperature interval 273 to 373 K. Crystalline strontium selenate was prepared by mixing stoichiometric amounts of strontium nitrate and selenic acid. Under the light microscope the crystals appear as very thin needles. The strontium concentration in saturated solution was obtained by polarographic (half-wave potential at -2.1 V) and gravimetric measurements. Both methods gave concordant results, Table A-18. 

D) and N acceptors (A) should be present (on an average) per one XO4 tetrahedron. When discussing the structures of hydrogen sulfates and selenates, we consequently start with lower IV values and finish with the maximum of =2 which corresponds to crystalline sulfuric and selenic acids. 

Thus, the main series of selenates, the octahydrates R2(Se04)3-8H20 (R = Pr-Lu,Y), is isostructural with the corresponding sulfate series (Rosso and Perret, 1970 Hiltunen and Niinisto, 1976a,b). The preparation of the crystalline compounds can be carried out by similar methods, viz. dissolving rare earth oxide, hydroxide, carbonate or chloride in selenic acid and letting the solution evaporate at room temperature. 

Copper sulphate solution bluish-green, crystalline precipitate of copper selenite, CuSe03, in neutral solution (difference from selenate). The precipitate is soluble in dilute acetic acid. 

---