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Determining the copper content of acid/copper sulphate solution


When determining the copper content of a simple acid/copper sulphate solution, the "Canning Handbook of Electroplating" suggests to plate out onto a pre-weighted cathode of platinum. Question: Can anybody explain the reason for using platinum as a cathode? And also, what should be used as an anode?

Best wishes,

John Herms
- Durban, Natal, South Africa


That's not the best way to determine the copper in an acid copper bath. Here: 5 ml bath, add 100 ml water, 1g sodium fluoride, 10 ml 10% potassium iodide solution. Titrate with .1M sodium thiosulfate solution to a straw color. Add iodine indicator and continue titrating until the blue color disappears. g/l Cu=1.27 x (mls of thiosulfate)

James Totter
James Totter, CEF
- Tallahassee, Florida


Thank you for your response to my enquiry. I do in fact use reagents to analyse my copper solution. However, my query was: WHY should I use a PLATINUM cathode and what should then be used as the anode in this electro metric method. This question is simply for my own education. Can you help me with this one?

John Herms
- South Africa


Since the handbook does not say, I can only make educated guesses as to what was in the author's mind. I would say the reason for a platinum cathode is to make sure none of the cathode dissolves into the solution, throwing off the weight calculation. The anode obviously must be insoluble; therefore platinum would be good there as well.

As for Jim's answer, please remember that "Dear Abby" and "Hints from Heloise" are not intended to be free, individualized, consulting services. They are published forums, intended primarily for the benefit of the readership. It's the same thing here: titration is a better method, so Jim was correct, and doing a public service, in pointing that out to the readers.

You're the one who posted your question in abstract fashion despite our repeated requests for you to be forthright and specific about who you are, why you want to know, and the actual real-world situation that impels your questions :-)

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

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