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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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ANALYSIS OF A ZINC CYANIDE PLATING BATH
Q. I AM A FOREMAN IN ELECTROPLATING. MY PROBLEM IS THE ANALYTICAL TITRATION OF A CYANIDE ZINC BATH. TO FIND HOW MUCH SODIUM HYDROXIDE IS PRESENT IN THE BATH WE HAVE TO TITRATE A SAMPLE SOLUTION AGAINST N sulfurIC ACID. AS CHROME RED IS UNAVAILABLE WHAT OTHER INDICATOR CAN I USE. KEEP IN MIND WE ARE TITRATING sulfurIC ACID AGAINST A SOLUTION HAVING SODIUM HYDROXIDE AND CYANIDE.
Malcolm KaviratneELECTROPLATING FOREMAN - Albuquerque, New Mexico, U.S.A.
2004
A. When analyzing the Cyanide Zinc bath, I will suppose that you are using a full strength cyanide system. After pipetting the sample into a 125 ml Erlenmeyer Flask
⇦[125 mL flasks on
eBay or
Amazon [affil links]
, I add 10% NaCN solution and a few drops of sulfo orange
⇦ this on
eBay or
Amazon [affil links]
Indicator. Then, titrate with Standard 1.0 Normal Sulfuric Acid until you achieve an orange > yellow endpoint. The pH of the finished titration will be above the point whereby hydrogen cyanide is generated. Mls. of 1.0N Acid X 1.07 = oz/gallon Sodium Hydroxide.
Good luck,
Ed Budman [dec]
- Pennsylvania
With deep sadness we advise that our good friend Ed passed away Nov. 24, 2018
2004
A. Try 10 mls bath solution in a nessler cylinder add 10 mls KCN(10%)and 8 drops troepelin O indicator dilute to 25 mls with demin. Titrate with N sulfuric and match colour with a blank containing no bath solution but containing indicator and KCN add water equally to both (colour initially orange on adding acid will turn yellow matching your blank) and your titre multiply by 8.0 to give Gram per litre of NaOH in your zinc bath.
Best of British
Ian Jones
Wrexham Clwyd
- wrexham wales
2004
A. I prefer to use indigo carmine solution as an indicator. This will give a sharp endpoint (green). I have found many people to have trouble seeing the color change using LaMotte sulfo orange ⇦ this on eBay or Amazon [affil links] .
Gene Packmanprocess supplier - Great Neck, New York
2004
A. Like Gene Packman, I dislike sulfo orange ⇦ this on eBay or Amazon [affil links] . I have tried various alternate indicators in order to find the best method. What I ended up deciding is that I achieve the best and most consistent results by titrating to a pH 11.0 with a pH meter calibrated with 11.0 buffer solution. This takes the question of the correct color out of the equation. If you decide to do it this way, I have found that it is critical to purchase the 11.0 buffer and not rely on the 10.0 buffer to give you a consistent value at 11.0.
Jon Barrows, MSF, EHSSC
GOAD Company
Independence, Missouri
2004
[editor appended this entry to this thread which already addresses it in lieu of spawning a duplicative thread]
Q. We use a cyanide zinc bath,. I would be highly pleased if you can inform me of a suitable method of finding the composition of the plating bath.
Zinc, Cyanide and Caustic. I would be highly grateful if a suitable titration or volumetric analysis or any other method can be advised ?
- London, UK
November 5, 2008
Q. Hi, is it possible to use indigo carmine in copper cyanide baths, to detect potassium hydroxide in the bath, what is the procedure? Thanks.
Nilufer Ulgudur- Ankara, Turkey
June 13, 2013
A. I agree wholeheartedly with Jon.
You can make your own pH 11 buffer. Just look in the CRC for the formula.
Dave Wichern
Consultant - The Bronx, New York
June 17, 2013
Q. Dear All,
Would you like to inform us about determination of zinc oxide
⇦ this on
eBay or
Amazon [affil links]
(ZnO), sodium cyanide (NaCN), and sodium hydroxide (NaOH) in a cyanide zinc bath solution with titration method? Thanks for your help.
- Jakarta, Indonesia
November 22, 2018
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