Chemgineer
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Potassium Chlorate - Yellow Colour Change
I've been electrolysing a solution of Muriate of Potash (fertiliser grade Potassium Chloride) after first filtering out all of the brown particulate.
It works really well.
What i'm interested in is when I reuse the solution I can get a bright yellow colour after adding more KCL to bring it back to saturation. This fairly
quickly goes colourless again once the electrolysis starts.
What could the colour be? I am wondering if this is Sodium Chlorate in solution from sodium impurities in my Muriate?
[Edited on 5-6-2021 by Chemgineer]
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hissingnoise
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Chlorine in solution, most likely ─ from acid hydrolysis of some hypochlorite...
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Chemgineer
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Thanks, that makes sense and then it releases as Chlorine gas once the electrodes get to work.
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mysteriusbhoice
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yellow color is due to potassium hypochlorite and usually with pH of 11 these cells operate at a high enough pH that considerable hypochlorite remains
dissolved as the cell runs.
I hope you didnt add more KCl as your anodes were left unpowered in the cell or rather you never left your anodes unpowered in a cell if its MMO as
that can lead to highly toxic RuO4 which is a deep yellow color being produced.
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Chemgineer
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Thanks for the explanation, I never leave electrodes in the cell unpowered so nor worries there. The yellow change happened literally while adding
the KCL, it looks like i'm pouring a yellow liquid in so whatever it is reacts between KCL and my chlorate brine.
It clears up again once the cell is run for a few minutes.
Also last time I checked after adding KCL, PH test paper appeared to show the cell was around PH 5 or 6. (My test strip just stayed yellow.)
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