Sodium ammonium chromate solubility

In laboratory investigations, hexavalent chromium compounds, such as chromic oxide (CTO3), are often used as the source of chromium, because of their high solubilities in water. Ammonium chromate or ammonium dichromate can also be used, whereby the NH4+ ion is lost during calcination. However, sodium or potassium chromates or dichromates are unsuitable because they leave alkali metal ions on the catalyst that can promote sintering. Other hexavalent chromium compounds that have been used in nonaqueous environments include chromyl chloride and even organic chromates such as bis(f-butyl) chromate. Early Phillips commercial catalysts used aqueous CrOs as the source. 

Both Cr(III) and Cr(VI) form compounds whose water solubilities range from very high to very low. Many compounds of industrial importance, such as the sodium, potassium, and ammonium chromates and dichromates, chromium trioxide (CrOs), and the hydrated Cr(III) nitrate, chloride. 

Sulfoalkylated naphthol compounds are effective as dispersants in aqueous cement slurries. The compounds can also be applied in an admixture with water-soluble inorganic compounds of chromium to provide additives of increased overall effectiveness. Particularly suitable are sodium chromate or ammonium dichromate. a-Naphthol is reacted in an alkaline aqueous medium with formaldehyde to create condensation products. The aldehyde can be reacted with bisulfite to produce sulfoalkylated products [1404,1410]. 

The effects of various metal oxides and salts which promote ignition of amine-red fuming nitric acid systems were examined. Among soluble catalysts, copperQ oxide, ammonium metavanadate, sodium metavanadate, iron(III) chloride (and potassium hexacyanoferrate(II) with o-toluidine) are most effective. Of the insoluble materials, copper(II) oxide, iron(III) oxide, vanadium(V) oxide, potassium chromate, potassium dichromate, potassium hexacyanoferrate(III) and sodium pentacyanonitrosylferrate(II) were effective. 

Catalytic elfects on the thermal decomposition and burning under nitrogen of the nitrate were determined for ammonium dichromate, potassium dichromate, potassium chromate, barium chloride, sodium chloride and potassium nitrate. Chromium(VI) salts are most effective in decomposition, and the halides salts during burning of the nitrate [1]. The effect of chromium compounds soluble in the molten nitrate, all of which promote decomposition of the latter, was studied (especially using ammonium dichromate) in kinetic experiments [2],... 

All carbonates, phosphates, chromates, and silicates are insoluble, except those of sodium, potassium, and ammonium. An exception is MgCr04 which is soluble. 

M. Couleru recommends the use of a cone. soln. of sodium chromate for the successful production of perchlorates. The action is similar to that which is obtained by a little chromate in the electrolyte during the production of chlorates. The sodium perchlorate so produced is very soluble and deliquescent, and it is not usually worked up, but rather converted into the ammonium or potassium salt by the addition of ammonium or potassium chloride. It is advisable to ensure that all the chlorate has been converted into perchlorate before precipitating the perchlorate, otherwise the perchlorate will be contaminated by the chlorate in solid soln. which cannot be removed by washing. A. Angeli recommends electrolyzing... 

H. Stamm also measured the solubilities of the salts of the alkalies in liquid ammonia —potassium hydroxide, nitrate, sulphate, chromate, oxalate, perchlorate, persulphate, chloride, bromide, iodide, carbonate, and chlorate rubidium chloride, bromide, and sulphate esesium chloride, iodide, carbonate, and sulphate lithium chloride and sulphate sodium phosphate, phosphite, hypophosphite, fluoride, chloride, iodide, bromate, perchlorate, periodate, hyponitrire, nitrite, nitrate, azide, dithionate, chromate, carbonate, oxalate, benzoate, phtnalate, isophthalate ammonium, chloride, chlorate, bromide, iodide, perchlorate, sulphate, sulphite, chromate, molybdate, nitrate, dithionate, thiosulphate, persulphate, thiocyanate, phosphate, phosphite, hypophosphite, arsenate, arsenite, amidosulphonate, ferrocyanide, carbonate, benzoate, methionate, phenylacetate, picrate, salicylate, phenylpropionate, benzoldisulphonate, benzolsulphonate, phthalate, trimesmate, mellitate, aliphatic dicarboxylates, tartrate, fumarate, and maleinate and phenol. 

Lead acetate solution white precipitate of lead sulphate, PbS04, soluble in hot concentrated sulphuric acid, in solutions of ammonium acetate and of ammonium tartrate (see under Lead, Section III.4, reaction 5), and in sodium hydroxide solution. In the last case sodium tetrahydroxoplumbate(II) is formed, and on acidification with hydrochloric acid, the lead crystallizes out as the chloride. If any of the aqueous solutions of the precipitate are acidified with acetic acid and potassium chromate solution added, yellow lead chromate is precipitated (see under Lead, Section III.4, reaction 6). 

Solubility The chromates of the alkali metals and of calcium and magnesium are soluble in water strontium chromate is sparingly soluble. Most other metallic chromates are insoluble in water. Sodium, potassium, and ammonium dichromates are soluble in water. 

Separation. — The separation of thorium from the rare earth metals with which it is still mixed may be accomplished by three methods (1) the carbonate separation depends on the fact that thorium carbonate is much more soluble in sodium carbonate than the carbonates of the rare earth metals (2) by the fractional crystallization of the mixed sulfates at 15°-20°, crystals of Th(S04)2 8 H20 are obtained at the insoluble end of the series (3) thorium oxalate forms a soluble double salt with ammonium oxalate, while the rare earth oxalates are almost insoluble in this reagent. Some other methods which have been suggested are fractionation of the chromates,4 of the hydrogen alkyl sulfates,5 of the acetates, by the use of sebacic add 6 and hydrogen peroxide. 

Inorganic anodic and mixed Cl present water-soluble salts of ammonium, alkali (sodium, potassium), alkaline-earth (calcium, strontium, magnesium, barium) and other (zinc, lead) metals containing active anions in their molecules (nitrates, nitrites, chromates, carbonates, phosphates, molybdates, silicates). ... 

The line db. Fig. 47, is the solubility curve -with CrOs as solid phase be, with Cs2Cr40i3 cd, with Cs2Cr30io de, with Cs2Cr207 ef, with Cs2Cr04 and, with Cs0H.nH20. The sodium and ammonium salts are alone hydrated in the ternary systems at 30° and the solubilities of the different alkali chromates at 30° are ... 

---