Potassium tetraperoxochromate(V)

Potassium tetraperoxochromate(V)

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Identifiers
CAS Number	12331-76-9 Y
Properties
Chemical formula	K 3CrO 8
Molar mass	297.286
Appearance	red brown
Vapor pressure	{{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Potassium peroxochromate, or potassium tetraperoxochromate(V), is an inorganic chemical having the chemical formula K₃[Cr(O₂)₄]. A crystalline ionic solid with a brown color, it is the potassium salt of tetraperoxochromate(V), one of the few examples of chromium in the +5 oxidation state.

Preparation

Potassium peroxochromate is prepared by reacting hydrogen peroxide with potassium chromate at low temperatures:

2 CrO²⁻
₄ + 8 H
₂O
₂ → 2 [Cr(O
₂)
₄]²⁻
+ 8 H
₂O

The intermediate tetraperoxochromate(VI) is reduced by hydrogen peroxide, forming tetraperoxochromate(V):

2 [Cr(O
₂)
₄]²⁻
+ 2 OH⁻
+ H
₂O
₂ → 2 [Cr(O
₂)
₄]³⁻
+ 2 H
₂O + O
₂

Thus, the overall reaction is:

2 CrO²⁻
₄ + 9 H
₂O
₂ + 2 OH⁻
→ 2 [Cr(O
₂)
₄]³⁻
+ 10 H
₂O + O
₂

The compound decomposes spontaneously at higher temperatures.