Metal finishing Q&As since 1989

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Removal of Sodium Carbonate

 

Hello Everyone,

I know by freezing Cadmium cyanide bath I can remove sodium carbonate but this piece of equipment is very expensive. I had tried using calcium sulphate and magnesium sulphate but for calcium sulphate I cannot tell the difference from carbonate and calcium sulphate as the results are both white wet powder. For magnesium sulphate the crystals turns wet powder purple dots and some white dots( a mixer)and the bottom a dark brown powder. This two chemicals was taken from a book but didn't state the colour change. The question is what must be the colour change for this two chemicals, calcium sulphate and magnesium sulphate after treating on cadmium cyanide?

Is there any better method ? This is a small lab experiment that I am doing.

Thank you,

Tessensohn Alicia
- Singapore

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I've never heard of removing carbonates that way and it would not surprise me if these soluble salts render the cadmium bath unuseable; but maybe it's okay and I just am not familiar with it. But how can the freezing equipment be "very expensive"? All you're really talking about is putting your beaker [beakers on eBay or Amazon] in a pan full of ice or dry ice, depending on how low a temperature you want for your experiment.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey