The authoritative public forum
  for Metal Finishing since 1989
-----

Nitric acid titration

How can we carry out nitric acid titration perfectly?

i.e. against which solution and using which indicator exactly?

We are titrating it against sodium carbonate?and methyl orange ⇦this on eBay or Amazon [affil links] indicator.

Is it perfect?/

Jyoti Panda
student - India
February 13, 2009

Methyl orange ⇦this on eBay or Amazon [affil links] is a good indicator. You do need to proceed slowly as you near the end point and you do need to have good mixing, or the pH will change after you have met the end point color change. This assumes that all of the carbonate is dissolved before you start the titration, or that you go very slow. I like it better than phenolphthalein.

James Watts
- Navarre, Florida

It would be good to know what else is in the solution.
If there are metals such as Fe or Cu then they will tend to precipitate near the endpoint and redissolve.
methyl orange ⇦this on eBay or Amazon [affil links] is an OK indicator for this pH change 3.2-4.4 but many males with colour insensitivity find the endpoint difficult to see.
Personally I would prefer sodium hydroxide as the titrant and maybe bromophenol blue ⇦this on eBay or Amazon [affil links] 3.0-4.6 as the indicator

Geoffrey Whitelaw
- Port Melbourne, Australia