Peroxochromic acid

Addition of hydrogen peroxide to a solution of a dichromate yields the blue colour of "peroxochromic acid. This is a test for soluble chromates and dichromates. 

Because of the two peroxide groups the compound is often called chromium peroxide. The name peroxochromic acid is less appropriate, because the compound does not contain hydrogen at all. In aqueous solution the blue colour fades rapidly, because chromium pentoxide decomposes to chromium(III) and oxygen ... 

In attempts to prepare perchromic acid , a mixture of silver (or barium) peroxochromate and 50% sulfuric acid prepared at -80°C reacted explosively on warming to about -30°C. 

Silver Peroxochromate, AgCrOj Reacts explosively with 50% sulfuric acid upon being warmed from —80° to —30° E.H. Riesenfeld et al, Ber 47, 548(1914)... 

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