Manganese potassium chromate

W. Ostwald considers that the presence of the highly oxidized salts—iodates and perchlorates—shows that the deposits were formed in an atm. highly charged with ozone. H. Guyard says the yellow coloration of some samples is due to the presence of potassium chromate and the violet to manganese nitrate. The... 

The existence of most of the double salts wluch have been described in the literature must be considered as extremely doubtful, but by adding manganous chloride to a concentrated solution of potassium chromate, potassium manganese chromate, K2Mn(Cr0j)2.2H20, has been obtained by Groger as a red crystalUne precipitate. 

Schemes have been devised to substitute less toxic metals for more toxic ones. Potassium ferrate on K10 mont-morillonite clay has been used to replace potassium chromate and potassium permanganate in the oxidation of alcohols to aldehydes and ketones in 54-100% yields.153 The potassium ferrate is made by the action of sodium hypochlorite on iron(III) nitrate or by treatment of iron(III) sulfate with potassium peroxymonosulfate.154 After the oxidation, any excess oxidizing agent, and its reduced form, are easy to recover by filtration or centrifugation. In another case, manganese-containing reagents have been substituted for more toxic ones containing chromium and selenium (4.21).155 Selenium dioxide was used formerly in the first step and pyridinium chlorochromate in the second.

Bismuth chromates group Calcium chromates group Copper chromates group Iron chromates group Lead chromates group Zinc chromates group Barium chromate(VI) Barium potassium chromate Cadmium chromate Crocoite Manganese chromate Mercury chromate Silver chromate Strontium chromate Thallium chromate Tin chromate... 

Copper chromate oxide hydrate Cobalt chromate Iron dichromate Iron chromate hydroxide Manganese chromate hydrate Silver chromate Thallium chromate Titanium chromate Cadmium chromate Cadmium chromate hydroxide Mercury chromate Zinc dichromate hydrate Zinc chromate(VI) hydroxide Zinc sodium chromate Zinc potassium chromate... 

The relation of Mnn oxidised to Asm oxidised is known as the induction factor, and is found to be about 0-5 at the beginning of the reaction, whatever amount of manganous salt may be present but the value diminishes as the action proceeds, for as the chromate concentration falls, the tervalent manganese is reduced by the tervalent arsenic to an increasing extent. The presence of a trace of potassium iodate produces great irregularity in the induction factor and lowers its initial value to about 0-25. 

Manganates.—Oxides of manganese, if heated with caustic alkalies in a current of air, or with potassium or sodium nitrate, are converted into manganate the manga-nate, however, is much more easily decomposed than the chromate, and, indeed, is stable only in presence of excess... 

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