Chromium ammonium sulfate

Chromium ammonium sulfate (I2H2O) [34275-72-4 (hydr) I3548-43-I (anhydr)] M 478.4, m 94 loses 9H2O then dehydr at 300 , d 1.72. Crystd from a saturated aqueous soln at 55° by cooling slowly with rapid mechanical stirring. The resulting fine crystals were filtered on a Buchner funnel, partly dried on a porous plate, then equilibrated for several months in a vacuum desiccator over crude chromium ammonium sulfate (partially dehydrated by heating at 100° for several hours before use) [Johnson, Hu and Horton J Am Chem Soc 75 3922 1953]. 

Alum Ammonium alums are those alums, such as aluminum ammonium sulfate A12(NH4)2 (804)4 24H20, ferric ammonium sulfate Fe2(NH4)2< S04)4 - 24H2O, chromium ammonium sulfate Cr2(NH4)2 (S04)4 24H2O where ammonium sulfate is crystallized with the heavier metal sulfate. 

Chromium Ammonium Alum of Chromium Ammonium Sulfate. See Ammonium-Chrome Alum in Vol 1, pA156-L... 

Chromium ammonium sulfate (I2H2O) [34275-72-4 (hydrate), 13548-43-1 (anhydrous)] M 478.4, m 94 loses 9H2O then dehydrates at 300°, df 1.72. Crystallise the double salt from a saturated... 

Ohio, high carbon ferrochromium is leached with a hot solution of reduced anolyte plus chrome alum mother Hquor and makeup sulfuric acid. The slurry is then cooled to 80°C by the addition of cold mother Hquor from the ferrous ammonium sulfate circuit, and the undissolved soHds, mostiy siHca, are separated by filtration. The chromium in the filtrate is then converted to the nonalum form by conditioning treatment for several hours at elevated temperature. 

Once the green, nonalum modifications of the chromium ion have formed, reversion to the hexaaquo form on cooling is sufficiendy slow that on chilling to 5°C a cmde ferrous ammonium sulfate can be crystallised, removing neady all the iron from the system. This cmde iron salt is treated with makeup ammonium sulfate, heated again to retain the chromium impurities in the green noncrystallisahle form, and then cooled to separate the bulk of the iron as a technical ferrous ammonium sulfate, which is sold for fertiliser and other purposes. The mother Hquor from this crystallisation is returned to the filtration step. 

After the chromium (II) chloride solution has been transferred to flask B, the flow of ammonia through the reaction vessel should be started. The ammonia delivery tube should approach but not dip below the liquid level in flask B. If tank ammonia is used, the tank should be opened carefully to avoid spattering of liquids by a sudden burst of gas. If ammonia is to be generated, the ammonium sulfate solution should be added carefully to the potassium hydroxide in flask C. It may be necessary to cool flask C with ice at first, then to warm the generator later in order to maintain a reasonably constant flow of ammonia. The use of tank ammonia avoids these problems. If zinc was used in the reduction, a precipitate of zinc hydroxide forms first and redissolves. The violet-blue solution stirred at 0° is saturated with ammonia, then a 2- to 3-g. sample of the platinum catalyst is added rapidly to flask B. A strong countercurrent of nitrogen is used to prevent entrance of air into the system when the catalyst is added. The reaction mixture is allowed to stir for one hour while the flask is cooled with ice. 

Ammonium sulfate, 4574 Barium sulfate, 0217 Calcium sulfate, 3939 Chromium(II) sulfate, 4244 Copper(II) phosphinate, 4272 Copper(II) sulfate, 4282 Iron(II) sulfate, 4399... 

Aluminium, 0048 Ammonium phosphinate, 4554 Barium phosphinate, 0210 f Benzaldehyde, 2731 1,4-Benzenediol, 2333 Bis(hydrazine)tin(II) chloride, 4070 Calcium acetylide, 0585 Calcium phosphinate, 3931 Chromium(II) chloride, 4052 Chromium(II) oxide, 4241 Chromium(II) sulfate, 4244 Copper(I) bromide, 0265 Diacetatotetraaquocobalt, 1780 Diisobutylaluminium hydride, 3082 f 1,2-Dimethylhydrazine, 0955... 

Elemental composition Cr 52.00%, 0 48.00%. The compound may he identified from its dark red color. Other color phases are noted above. Chromium may he measured in the aqueous phase hy AA, ICP or x-ray techniques, or in the solid phase hy x-ray methods. Hexavalent chromium (Cr6+) may he analyzed hy ion chromatography. For this, the aqueous sample is adjusted to pH 9 to 9.5 with a concentrated buffer (ammonium sulfate and ammonium hydroxide mixture) and mixed into the eluent stream of the buffer. Cr " is separated from Cr + on a column, and derivatized with an azide dye as a colored product measured at 530 nm, which is identified from its retention time. (APHA, AWWA, and WEF. 1999. Standard Methods for The Examination of Water and Wastewater, 20th ed., Washington, DC American Public Health Association.)... 

The Cr1 ion readily forms complexes it exists in aqueous solution as CrfH 0)j. and forms other complexes wilh anions, such asCr(H 0).CI , Crother properties due to variation in the bonding. Compounds or the trichloride have been reported with the following arrangements CrtHjOlsClj. [CrfHiOlsCljCIi- HiO. and [Cr(HiO)4Cf CU2 H 0 Trivalenl chromium also forms double salts, notably the chromium alums, hydrated double salts of Cr(III) sulfate and the alkali metal (or thallium or ammonium) sulfates. 

Aluminium, 0048 Ammonium phosphinate, 4549 Barium phosphinate, 0210 f Benzaldehyde, 2727 1,4-Benzenediol, 2326 Bis(hydrazine)tin(II) chloride, 4064 Calcium acetylide, 0582 Calcium phosphinate, 3925 Chromium(II) chloride, 4046 Chromium(II) oxide, 4235 Chromium(II) sulfate, 4238 Copper(I) bromide, 0264 Diacetatotetraaquocobalt, 1774 Diisobutylaluminium hydride, 3076 f 1,2-Dimethylhydrazine, 0951 1,2-Diphenylhydrazine, 3511 Dipotassium phosphinate, 4425 f Ethanedial, 0719 f Formaldehyde, 0415 Formic acid, 0417 Gallium(I) oxide, 4405 Glucose, 2513 f Hydrazine, 4515 Hydroxylamine, 4493 Hydroxylaminium phosphinate, 4550 Hyponitrous acid, 4464 Iron(II) chloride, 4055 Iron(II) hydroxide, 4386 Iron(II) sulfate, 4393 Fead(II) phosphinate, 4526 Fead(II) phosphite, 4530 Fithium dithionite, 4682 Magnesium, 4685 Magnesium phosphinate, 4512 Manganese(II) phosphinate, 4514 f Methylhydrazine, 0500 Phenylhydrazine, 2366 Phosphinic acid, 4498 Phosphonic acid, 4499 Phosphonium iodide, 4510 Potassium, 4640 Potassium hypoborate, 0163... 

Some chemicals that are reported to stimulate glowing are chromates, molybdates, halides of chromium, manganese, cobalt and copper, and ferric and stannic oxides (.5,10) Chemicals found to be ineffective in retarding afterglow in a limited study were ammonium sulfate and sodium borates (10). ... 

Five grams (0.0135 mol) of tris(biguanido) chromium (III) 1-hydrate is dissolved in 200 ml. of water and treated with a solution of 5,7 g. (0.043 mol) of ammonium sulfate in 10 ml. of water. The sparingly soluble tris(biguanide)-chromium sulfate is precipitated with liberation of ammonia. The mixture is heated on the water bath, whereby... 

Characteristic Chromium(lll) sulfate Sodium chromite (Chromium(lll)) Chromium(IV) oxide Ammonium dichromate (Chromium(VI))... 

Trivalent chromium pigments include chromium oxide (Cr203) and hydrated chromium oxide (Cr203 xH20). Chromium oxide is prepared by calcination, either by reduction of sodium bichromate (Na2Cr207) with sulfur or carbon at 750-900°C or by reduction of sodium bichromate with ammonium chloride or ammonium sulfate at 700°C. Hydrated chromium oxide is manufactured by hydrolyzing a complex chromium borate, which in turn has been produced by heating sodium bichromate with boric acid in a furnace. 

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