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Determine the rochelle salt of an alkaline copper bath

How to determine the rochelle salt [on eBay or Amazon] concentration of an alkaline copper plating bath

Oscar Villalobos
plating shop employee - Guadalajara. jalisco, Mexico
February 6, 2009

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The following is a method from page 105 of Analysis of Electroplating and Related Solutions [affil link on Amazon, ... on AbeBooks] by Parker and Langford (4th edition):

pipette [pipettes on eBay or Amazon] a 5 ml sample into a 250 ml beaker [beakers on eBay or Amazon] and add 5 ml concentrated hydrochloric acid. Boil to destroy cyanides and drive off hydrochloric acid. Do not evaporate to dryness. Cool, add 2 grams zinc dust [on eBay or Amazon] and allow to react for about 30 minutes stirring occasionally. Filter through a 41 or 31 paper and ash with water. To the filtrate in a 250 ml Phillips beader add 1 gram of manganese sulphate, 10 ml of 25% sulfuric acid and then exactly 50 ml of N/10 potassium permanganate [on eBay or Amazon]. Heat at 80-90 deg C, but do not boil for approx. 30 minutes. Coll to room temperature and add 3 grams of potassium iodide then titrate the liberated iodine with N/10 sodium thiosulphate [on eBay or Amazon] to the normal starch end point. The ml potassium permanganate minus the mls sodium thiosulphate gives the permanganate used in the oxidation since the two solutions are equiv.

ml N/10 KMnO4 x .9375 = g/l COOK.CHOH.CHOH.COONa.4H20

I wish for you to note that the above procedure, in my opinion should be performed under an adequate exhaust hood and that all proper safety precautions should be observed.

Gene Packman
process supplier - Great Neck, New York
February 11, 2009

See page 456 of the 2007 Metal Finishing Guidebook. The last analysis is for Rochelle salt (potassium-sodium tartrate).

Kurt Sammons
- Inman, South Carolina
February 12, 2009