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Nitric acid analysis in chromating solution

Q. Hello to all,
can any one please give me the method for analysis of Nitric acid (65% ) in yellow chromating solution we are facing a big problem in maintaining the nitric acid in yellow chromating solution as we are new to this process
Thank you.

Aboo Backer
plater - Bangalore, India
May 28, 2010

The OEM for the chromating solution will be happy to provide that information. If you have a home brew, then you will have a problem establishing a value to test to as the tank solution ages.

James Watts
- Navarre, Florida

A. 1. 5 mL sample of bath in a 250 mL Erlenmeyer flask [affil links].
2. 75 mL deionized water [affil links].
3. 5 drops phenolphthalein [on eBay & Amazon] indicator.
4. titrate against 1.0N sodium hydroxide 1N [affil links] solution. color change will be pale orange to dark pink-red.
v/v% HNO3 = mL 1.0N NaOH x 1.43

Randall Fowler - Fowler Industrial Plating, LLC
Cleveland, Tennessee, USA

A. I believe you can do this testing through an automated thermotitration. It easy and very accurate.

Tony Paulin
- Bardstown, Kentucky, USA
February 27, 2011

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