Potassium carbonate dichromate

Zirconium reduces almost all oxygen-containing salts. This is the case for alkali hydroxides (accidents with the lithium, sodium and potassium compounds) and zirconium hydroxide, lithium, sodium and potassium carbonates, alkaline sulphates sodium tetraborate and copper (II) oxide. This is true especially for oxidising salts such as alkaline chromates and dichromates, chlorates (accident with potassium salt) and nitrates (accident with potassium salt). 

Potassium chromate also can be prepared by heating a mixture of pure potassium dichromate and potassium carbonate in a moist atmosphere. The salt is dried and purified by recrystallization. 

Potassium dichromate also is produced from chrome ore. Ore is roasted with potassium carbonate or hydroxide to form potassium chromate ... 

Magnesium carbonate V Manganese carbonate P. 70 Manganese dioxide, powder IV, XI Nickel carbonate XI Phosphorus, red II, X Porcelain chips, unglazed E. 5, P. 56 Potassium carbonate IX Potassium chlorate III, VIII Potassium dichromate IV Potassium hydroxide II, III Potassium iodate VIII Potassium iodide IV, VIII Potassium nitrate IV, XI Potassium permanganate IV, VIII Potassium sulphate Q. 3 Silicon dioxide, precipitated IX Silicon dioxide, coarse sand P. 66, 67 Silicon dioxide, fine sand P. 8, 43 Sodium bicarbonate P. 55 Sodium bromide IV Sodium carbonate, anhydrous III, IX, XI... 

Potassium-Graphite, 122, 378, 476 Potassium 3-aminopropylamide, 378-379 Potassium f-amyloxide, 378 379 Potassium benzeneselenolate, 373 Potassium bis(trimethylsilyl)amide, 229 Potassium f-butoxide, 7, 380-381 Potassium f-butoxide-Benzophenone, 382 Potassium carbonate, 382-383 Potassium dichromate, 383 Potassium diisopropylamide-Lithium t-butoxide, 383-384... 

The chromates and dichromates are made by a method which has general usefulness for preparing salts of an acidic oxide—the method of fusion with an alkaline hydroxide or carbonate. The carbonate functions as a basic oxide by losing carbon dioxide when heated strongly. Potassium carbonate is preferred to sodium carbonate because potassium chromate and potassium dichromate crystallize well from aqueous solution, and can be easily purified by recrystallization, whereas the corresponding sodium salts are deliquescent and are difficult to purify. 

Preparation.—Metallic chromium is usually obtained by reduction of the sesquioxide, CtjOj, the chief source of which is chrome iron ore (p. 7). The latter, after separation from gangue, is powdered, washed, mixed with lime and potassium carbonate, dried, and then roasted, the mass being continually stirred. The potassium chromate produced is extracted with water and converted into the dichromate by treatment with sulphuric acid. After recrystallisation the potassium dichromate is reduced by heating wth sulphur, starch, or other suitable material, and finally washed with water the chromium sesquioxide remains undissolved. 

Potassium Chromate, KjCrOj, is usually prepared fi-om the dichromate vide infra) by neutralisation of the excess of CrOa above that necessary to form the normal salt, e.g. by potassium carbonate in aqueous solution by fusion of the dichromate with potassium nitrate or potassium carbonate, and extraction with water by interaction of potassium dichromate with ammonium chloride or sodium hydrogen phosphate. ... 

Potassium Dichromate, KjCcjO, may be prepared from the sodium salt and potassium chloride, or by a direct method. In the latter ease, chrome iron ore (p. 7) is calcined in the air with calcium carbonate, and the mass extracted with water containing a little sulphuric acid. Potassium carbonate is then added, and, after filtration and addition of sulphuric acid, the potassium dichromate is separated by fractional crystallisation. An alternative method consists in heating chromite with calcium carbonate and potassium sulphate, and lixiviating the mass with water. Oxidation of chromite by means of fused potassium nitrate is sometimes convenient, especially upon a small scale. Potassium dichromate is formed by the addition of any acid to a solution of potassium chromate (see p. 4.4 ). ... 

Chromite, FeCr204, is the principal ore of chromium. Chromates and dichromates are obtained from it by fusion with sodium or potassium carbonate with access of air the iron is oxidized from the ferrous to the ferric condition and the chro-... 

If calcium chromate be treated with a soln. of potassium sulphate, the calcium chromate is converted into calcium sulphate, which is precipitated, and potassium chromate, which remains in soln. Instead of leaching the calcium chromate with a soln. of potassium sulphate, W. J. Chrystal showed that if ammonium sulphate is used, a soln. of ammonium chromate is produced, and J. J. Hood found that if the soln. of potassium salt be treated with sodium hydrosulphate, potassium sulphate crystallizes from the soln., while sodium dichromate remains in soln. According to F. M. and D. D. Spence and co-workers, if a mixtiu-e of ammonia and carbon dioxide be passed into the aq. extract of the calcium chromate. Calcium carbonate is precipitated while ammonium and alkali chromate remain in soln. If the liquid be boiled, ammonia is given off, and sodium dichromate remains in soln. S. Pontius used water and carbon dioxide under press, for the leaching ptocess. J. Brock and W. A. Rowell purified alkali chromite by treating the soln. with strontium hydroxide, and digesting the washed precipitate with a soln. of alkali sulphate or carbonate W. J. A. Donald used calcium hydroxide or barium chloride as precipitant. A mixture of chromite with calcium carbonate and potassium carbonate was formerly much employed. Modifications of the process were described by W. J. A. Donald, A. R. Lindblad, C. J. Head, 8. G. Thomas, W. Gow, J. Stevenson and T. Carlile, L. I. Popoff,G. Bessa, P.Weise, P. N. Lukianoff,... 

Potassium compounds are among the most important base chemicals, especially potassium hydroxide (caustic potash) KOH, potassium nitrate (saltpeter) KNO3, potassium carbonate (potash) K2CO3, potassium chloride KCl, potassium chlorate KCIO3, potassium bromide KBr, potassium iodide Kl, potassium cyanide KCN, potassium sulfate KjSO, and potassium dichromate Ci 20j. 

DEKTAL DEVELOPER KODAK FIXER KODAK SHORT STOP POTASSIUM ALUM POTASSIUM BICARBONATE POTASSIUM BICHROMATE POTASSIUM BORATE POTASSIUM BROMATE POTASSIUM BROMIDE POTASSIUM CARBONATE POTASSIUM CHROMATE POTASSIUM CHLORATE POTASSIUM CHLORIDE POTASSIUM CYANIDE POTASSIUM DICHROMATE POTASSIUM FERRICYANIDE POTASSIUM FERROCYANIDE POTASSIUM FLUORIDE POTASSIUM HYDROXIDE POTASSIUM NITRATE POTASSIUM PERBORATE POTASSIUM PERCHLORATE POTASSIUM PERMANGANATE. 10% POTASSIUM SULFATE PROPANE PROPANE GAS PLATING SOLUTIONS BRASS CADMIUM COPPER GOLD INDIUM LEAD NICKEL RHODIUM SILVER TIN ZINC... 

The first chemical conversion coating process was developed by O. Bauer and O. Vogel in 1915. It consists of treating aluminium in a solution of potassium carbonate, sodium bicarbonate and potassium dichromate for 2 h at 90 °C. A dark grey layer is formed by this process. 

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