Permanganate visible spectrum

Table 16.1 summarizes the approximate colors associated with different wavelengths in the visible spectrum. As an example, a solution of potassium permanganate absorbs light in the green region of the spectrum with an absorption maximum of 525 nm, and the solution is purple. 

This complex was found to constitute 20 % of the hydrolysis mixture and can be eluted from the column with 0.6 M sodium perchlorate solution adjusted to pH 2.0. A chromium to cyanide ratio of 1 1.00 was determined by analysis for this pink, permanganate-colored species. The visible and ultraviolet spectrum of cyanopentaaquochromium(III) ion is independent of pH in the regions from 2 to 3.5 and is included in Fig. 4. The positions of the maxima (in mp) and corresponding molar absorbancy indices (in / mole cm ) in 0.6M sodium perchlorate are 525 (26.0), and 393 (20.5). The strong absorption band in the ultraviolet shows a point of inflection a = 268 I mole" cm" ) at 235 mp. The positions of the absorption maxima are identical to those reported by Espenson. Dilute solutions (pH 2) of the monocyano complex can be stored at 0° for several days without serious decomposition. 

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