Metal finishing Q&As since 1989

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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 [on eBay or Amazon] indicator.

Is it perfect?/

Jyoti Panda
student - India
February 13, 2009

Methyl orange [on eBay or Amazon] 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 [on eBay or Amazon] 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 [on eBay or Amazon] 3.0-4.6 as the indicator

Geoffrey Whitelaw
- Port Melbourne, Australia