Potassium manganate(VII) forms an intensely purple solution in water. The colour is due to the manganese ion present. The formation of a strongly coloured c...
Question 1 Report
Potassium manganate(VII) forms an intensely purple solution in water. The colour is due to the manganese ion present. The formation of a strongly coloured compound like this is a characteristic property shown by which group of elements?
Answer Details
Intensely coloured compounds are a characteristic property of the transition elements, so the purple of potassium manganate(VII), KMnO4, points to manganese, a transition metal. Its ion absorbs part of the visible spectrum and the light that reaches the eye appears purple, and manganese existing here in a high oxidation state also illustrates variable oxidation state.
Compare this with the alkali metals of Group I, whose compounds such as sodium chloride are white and dissolve to colourless solutions, and with the noble gases, which are unreactive and form almost no compounds at all.
The strong colour is put to practical use: manganate(VII) fades as it is reduced, so the colour change signals when a redox reaction is complete.
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