Reduction of Potassium Dichromate

In acid solution, the reduction of potassium dichromate may be represented as ... 

The green colour due to the Cr3+ ions formed by the reduction of potassium dichromate makes it impossible to ascertain the end-point of a dichromate titration by simple visual inspection of the solution and so a redox indicator must be employed which gives a strong and unmistakable colour change this procedure has rendered obsolete the external indicator method which was formerly widely used. Suitable indicators for use with dichromate titrations include AT-phenylanthranilic acid (0.1 per cent solution in 0.005M NaOH) and sodium diphenylamine sulphonate (0.2 per cent aqueous solution) the latter must be used in presence of phosphoric) V) acid. 

Reduction of potassium dichromate (yellow-orange) to chromium(lll) ion (green) in the presence of alcohol and sulfuric acid... 

Table 1 shows the variable levels that were used in the screening experiment. The experiment evaluated the gel reaction of two polyacrylamide polymers with identical levels of hydrolysis (20 percent). The reduction of potassium dichromate with thiourea was used to produce Cr(III) and crosslink the polymers. 

Based on AA acidic reduction of potassium dichromate to generate Cr + and luminol-H202-Cr chemiluminescence reaction 1.3 X 10-3 No data <5.0 Pharmaceuticals 2000 118... 

Other chemiluminescence FIA methodologies for AA determination are based on AA acidic reduction of potassium dichromate to generate Cr(III) and subsequent luminol-hydrogen peroxide-Cr(III) chemiluminescence reaction [87,88], and on chemiluminescence reaction of AA with potassium permanganate in the presence of formaldehyde [89,90], formic acid [91], or CdTe nanocrystals [92] as sensitivity enhancers. Quinine is also used as an enhancer of chemiluminescence produced by reaction between AA and Ce(IV) in acid media [93]. Perez-Ruiz et al. [94] proposed a chemiluminescent reaction, in alkaline solution, of lucigenin with the products from the photooxidation of AA sensitized by toluidine blue. 

Preparation and analysis of K3(Cr(C204)3].3H20 (Inorg.SynthA 939) 37) This can be prepared by the reduction of potassium dichromate with oxalic acid in presence of oxalate. It is envisaged that the first stage is the reduction of CKVI) to Cr(III), followed by the complex formation with the oxalate. 

Chromium metal can be electroplated from an aqueous solution of potassium dichromate. The reduction half-reaction is... 

Twenty-five grains of potassium dichromate (or lTg of chromium (VI) oxide) are dissolved in 500ml of water. Sulfur dioxide is bubbled into the solution until reduction to the trivalent state is complete, as indicated by the pure green color of the liquid with no trace of yellow. The solution is then boiled to remove excess sulfur dioxide. 

If chromic chloride is not available as a starting material for this procedure, the compound may be prepared in solution by reducing BOg of potassium dichromate with a mixture of 250ml of concentrated hydrochloric add and either 100ml of 95% alcohol, or HOg of oxalic acid 2-hydrate. The reduced solutions are then used directly in the reduction procedure only the zinc need be added. 

Potassium Chromium Alum, Chrome Alum, KjSOj. Cr2(S04)3.24H20, first isolated by Mussin-Pusehin, is obtained by the reduction of a mixture of potassium dichromate and sulphuric acid by sulphurous acid, alcohol, oxalic acid, etc. ... 

In the case of potassium dichromate we did not observe modifications of UV absorption spectra (which means that no direct bond to DNA bases is formed), while the effect on thermal stability differed "in vivo" and "in vitro", in both cases suggesting a break down of the molecule, supported by viscosity variations, too. These data are in agreement with the mutagenic (14) and carcinogenic (15) action of Cr I compounds and strengthen the hypothesis that Cr effect on the cells is mediated by oxidizing molecules produced by its intracellular reduction to Cr (9). 

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