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Author: Subject: Cleaning chromium(III) oxide stains from a flat bottom flask
andyloris
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[*] posted on 22-10-2022 at 08:52
Cleaning chromium(III) oxide stains from a flat bottom flask


I tried disolving chromium(III) oxide in hydrochloric acid, however it didn't work and I was left with chromium(III) oxide stains in my flat bottom flask.

How do I clean them ?

Thanks in advance !
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andyloris
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[*] posted on 29-10-2022 at 09:15


Guess my flask is gonna stay green forever ...
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Bedlasky
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[*] posted on 29-10-2022 at 09:27


I don't have experience with this issue, but when I needed clean something from Fe(OH)3, oxalic acid always worked very well. Try that. Or maybe bleach will help - it oxidize Cr2O3 to water soluble chromate. If Cr2O3 is deposited as a thin layer on the glass, you can try 40% NaOH - it eat away very small amount of glass and Cr2O3 won't stick to it anymore (and maybe even dissolve in NaOH).
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clearly_not_atara
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[*] posted on 29-10-2022 at 10:20


Could try forming the oxalate complex with refluxing potassium hydrogen oxalate?



[Edited on 04-20-1969 by clearly_not_atara]
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andyloris
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[*] posted on 29-10-2022 at 12:21


Thanks !
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macckone
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[*] posted on 31-10-2022 at 08:55


If hypochlorite does not work, there is always chlorate and bromate.
Depending on how tenacious the chromium oxide is, bromate may be the agent you need.
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