Potassium permanganate color

This experiment demonstrates the rapid oxidation of the sweet-tasting viscous alcohol glycerin by the powerful oxidizing agent potassium permanganate. The reaction produces a great amount of heat, which leads to a dramatic eruption of smoke and fire. The presence of potassium ions (from potassium permanganate) colors the flame violet. 

Reduction Tests. Corroborative data pertaining to further identification of these isolated spots can be obtained by subjecting the strips containing the steroids to reduction tests, such as the alkaline silver nitrate, triphenyltetrazolium chloride (2), or potassium permanganate color reactions, or to other types of characterizing procedures, which take advantage of the molecular structures of the compounds under consideration. 

The MauIg Color Reaction. The procedure for this test consists basically of three sequential treatments of lignified material with 1% potassium permanganate, 3% hydrochloric acid, and concentrated ammonium hydroxide. A red-purple color develops for hardwoods and a brown color... 

Principal uses of KOH include chemicals, particularly the production of potassium carbonate and potassium permanganate, pesticides (qv), fertilizers (qv), and other agricultural products soaps and detergents scmbbing and cleaning operations, eg, industrial gases dyes and colorants and mbber chemicals (qv) (10,34). 

Various methods can be used to analy2e succinic acid and succinic anhydride, depending on the characteristics of the material. Methods generally used to control specifications of pure products include acidimetric titration for total acidity or purity comparison with Pt—Co standard calibrated solutions for color oxidation with potassium permanganate for unsaturated compounds subtracting from the total acidity the anhydride content measured by titration with morpholine for content of free acid in the anhydride atomic absorption or plasma spectroscopy for metals titration with AgNO or BaCl2 for chlorides and sulfates, respectively and comparison of the color of the sulfide solution of the metals with that of a solution with a known Pb content for heavy metals. 

Preparation of Intermediate Compound 4-Chloro-5-Sulfamyl-N-Acetylanthranilic Acid To a hot solution (80°C) of 366 g (1.482 mols) of magnesium sulfate (Epsom salts) in 2.8 liters of water was added 130 g (0.495 mol) of powdered 5-chloro-2-methyl-4-sulfamyl-acetanilide. With stirring and maintaining the temperature at 83°C, 234 g (1.482 mols) of potassium permanganate was added portionwise over a period of 2 hours. The mixture was then kept at 85°C with stirring for an additional 3 hours. By this time the pink color of the permanganate had been discharged. 

Some of the substances you work with in general chemistry can be identified at least tentatively by their color. Gaseous nitrogen dioxide has a brown color vapors of bromine and iodine are red and violet, respectively. A water solution of copper sulfate is blue, and a solution of potassium permanganate is purple (Figure 1.14). 

Crystals of potassium permanganate falling into water. The purple color of the solution results from absorption at approximately 550 nm. 

As a more complex case, suppose we want to write the equation for the reaction that occurs when hydrogen sulfide gas, H2S, is bubbled into an acidified potassium permanganate solution, KMn04. When we do this, we observe that the purple color of the MnO ion disappears and that the resulting mixture is cloudy (sulfur particles). From Appendix 3 we find the two halfreactions... 

One other important compound of manganese is potassium permanganate, KMnO . This is an intensely violet-colored material much used as an oxidizing agent in the laboratory. (It is too expensive to use on a large scale in industry, chlorine is more likely to be used.)... 

B. Self-indicating reagents. This is well illustrated by potassium permanganate, one drop of which will impart a visible pink coloration to several hundred millilitres of solution, even in the presence of slightly coloured ions, such as iron(III). The colours of cerium(IV) sulphate and of iodine solutions have also been employed in the detection of end points, but the colour change is not so marked as for potassium permanganate here, however, sensitive internal... 

Standard solution of iron(III). Use method (a), (b) or (c). (a) Dissolve 0.7022g ammonium iron(II) sulphate in 100mL water, add 5mL of 1 5 sulphuric acid, and run in cautiously a dilute solution of potassium permanganate (2 g L 1) until a slight pink coloration remains after stirring well. Dilute to 1 L and mix thoroughly. lmL = 0.1mg of Fe. (6) Dissolve 0.864 g ammonium iron(III) sulphate in water, add 10 mL concentrated hydrochloric acid and dilute... 

With a solution of ninhydrin in pyridine, 4(5)-aminoimidazole (25 R = H) gave a grass-green color, and with ferric chloride solution in acetic acid a purple coloration was observed. Acidic solutions of bromine and potassium permanganate were decolourized by 4(5)-aminoimidazole (25 ... 

R = H) while with alkaline potassium permanganate a bright green color was obtained (41 Mil). 

Iodine in aqueous solution may be measured quantitatively by acidifying the solution, diluting it, and titrating against a standard solution of sodium thiosulfate, sodium arsenite or phenyl arsine oxide using starch indicator. The blue color of the starch decolorizes at the end point. The indicator must be added towards the end of titration when the color of the solution turns pale yellow. Prior to titration, iodine in the dilute acidic solution is oxidized to iodate by adding bromine water or potassium permanganate solution. Excess potassium iodide is then added. The liberated iodine is then titrated as above. 

The British Pharmacopoeia describes another identification test [32]. To 0.2 mL of a 10 % w/v solution, one adds 2 mL of water and 0.5 mL of 1 M sulfuric acid. The mixture is shaken, and then 1 mL of a 0.1 % w/v solution of potassium permanganate is added. A positive reaction is where the color is immediately discharged. 

The reaction mixture is cooled to room temperature, and a saturated solution of potassium permanganate is added in an amount sufficient for a violet color to persist for about 1 minute... 

Addition of potassium permanganate removes colored impurities that otherwise persist through subsequent distillations of the acid. The maximum concentration of potassium permanganate in water at room temperature is about 5%. It may be more convenient to use a concentrated solution of sodium permanganate, which is very soluble in water. However, the end point is difficult to observe with sodium permanganate. 

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