Chrome alum Chromic acid

Butyl alcohol Calcium chloride Calcium nitrate Chlorinated lime paste Chlorinated lime solution (2%) Chrome alum Chromic acid (20%)... 

Oxidation states of chromium - -2, - -3, and -f-6. Oi es of chromium chronate, FeCr204, and crocoite, PbCr04. Chromium metal and its alloys ferrochrome, alloy steels, stainless steel. The aluminothermic process (Goldschrtiidt process). Electrolytic chromium. Chromium trioxide, chromic acid, dichromic acid, potassium chromate, potassium didiromate, sodium chromate, lead chromate. Equilibrium between chromate ion and dichromate ion. Chrome-tanned leather. Chromic oxide (chrome green) chromic ion, chrome alum, chromic chloride, chromic hydroxide, chromite ion. Chromous compounds. Peroxy-chromic acid. 

The chemical properties of chromic oxide.—E. D. Clarke said that chromic oxide is not decomposed by the oxyhydrogen blowpipe flame and J. J. Berzelius found that it is not decomposed by hydrogen at a red-heat. For the electroxidation of chromic oxide, vide chromic acid, etc. According to R. Saxon traces of chromic acid are formed by the anodic oxidation of chromic oxide in pure water the addition of manganese dioxide to the chromic oxide increases slightly the yield of chromic acid. Much more rapid oxidation ensues in the presence of calcium or potassium hydroxide or both. In soln. of alkali chlorides containing a little chrome-alum, chromic oxide is rapidly oxidized at the anode to chromic acid. 

As an example of the problem of species in solution, consider the case of a solution made by dissolving some potassium chrome alum, KCrfSO s-12H20, in water. On testing, the solution is distinctly acidic. A currently accepted explanation of the observed acidity is based upon the assumption that, in water solution, chromic ion is associated with six H20 molecules in the complex ion, Cr(H20) a. This complex ion can act as a weak acid, dissociating to give a proton (or hydronium ion). Schematically, the dissociation can be represented as the transfer of a proton from one water molecule in the Cr(H20) 3 complex to a neighboring H20 to form a hydronium ion, H30+. Note that removal of a proton from an H20 bound to a Cr+3 leaves an OH- group at that position. The reaction is reversible and comes to equilibrium ... 

In a large lead-lined vessel, 300 grams of sublimed, still moist, anthracene (calculated on the basis of 100 per cent product) is stirred with 6 liters of water and 600 grams of sodium bichromate. The mixture is heated to 80°C. over a Fletcher burner, and 1800 grams of 50 per cent sulfuric acid is added over a period of 10 hours. Chromic-acid should always be present, and the mixture should be stirred with a wooden or glass rod. Finally, the mixture is boiled for 2 hours, replacing the water lost by evaporation. The precipitate is then filtered off and washed thoroughly. The mother liquor can be worked up to recover chrome alum or chromic sulfate. 

SYNS CHROME ALUM CHROME POTASH ALUM CHROMIC POTASSIUM SULFATE CHROMIC POTASSIUM SULPHATE CHROMIUM POTASSIUM SULFATE (1 1 2) CHROMIUM POTASSIUM SULPHATE CRYSTAL CHROME ALUM POTASSIUM CHROMIC SULPHATE POTASSIUM CHROMIUM ALUM POTASSIUM DISULPHATOCHROMATE(III) SULFURIC ACID, CHROMIUM (3+) POTASSIUM SALT (2 1 1)... 

Chromium in its Compounds is sometimes metallic and sometimes non-metallic toward the other components. Thus, in chromium trioxide, CrOg, the anhydride of the hypothetical chromic acid, H2Cr04, chromium acts as a non-metal, just like sulphur in sulphuric acid hence in chromates the chromium is acidic, or non-metallic, in its chemical relations with the other elements. In chromic compounds, however, chromium acts as a metal. Thus chromium hydroxide, Cr(OH)3, is analogous to aluminium hydroxide chrome alum is potassium chromium sulphate, and is analogous to aluminium alum. The two classes pass into each other by appropriate operations,... 

Chromic oxide jellies may be formed by adding sodium or potassium hydroxide or ammonia to a solution of chromic sulphate or chloride containing sodium acetate or by adding sodium or potassium hydroxide, hut not ammonia, to a solution of chrome alum. The jelly is violet if prepared by the addition of ammonia or of a slight excess of the alkali metal hydroxide if the latter is added in larger quantity the jelly is green. The jellies dissolve in hydrochloric acid, but re-form on neutralising the solution if sufficient sodium acetate is present. 

Basicity chrome alum CCRIS 7532 Chrome alum Chrome potash alum Chromic potassium sulfate Chromic potassium sulphate Chromium potassium bis(sulphate) Chromium potassium sulfate (1 1 2) Chromium potassium sulfate (CrK(S04)2) Chromium potassium sulphate Chromium(lll) potassium sulfate Crystal Chrome Alum EINECS 233401-6 Potassium chromic sulfate Potassium chromic sulphate Potassium chromium alum Potassium chromium disulfate (KCr(S04)2) Potassium disulphatochromate (III) Sulfuric acid, chromium(3 ) potassium salt (2 1 1). Mordant for dyeing fabrics uniformly [dodecahydratej mp = 89° d = 1.83 soluble in 4 parts H2O. 

For the electrolytic oxidation of soln. of chromic salts to chromic acid or the chromates, vide supra. According to E. Muller and M. Seller, a soln. of chrome-alum in i i-H2804 is not appreciably oxidized to chromic acid with a smooth platinum anode, but when traces of a lead salt are present in the soln., lead dioxide is deposited on the anode, and oxidation then occurs. About one-third of the oxidation which occurs with a lead dioxide anode occurs when an anode of platinized platinum is used. With a lead dioxide anode, the oxidation occurs quantitatively in fairly cone. soln. of chrome-alum, when the current density is not too high—about 0-005 amp. per... 

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