[sci994]

Guys
I have a question.When I do the Brown Ring test (test to prove presence of nitrates) do I use only HNO3 or any nitrate (like NaNO3 or Pb(no3)2 etc...)?If I have NaNO3 in a test tube should I add H2SO4 first to produce HNO3 and than to add FeSO4 and conc. H2SO4 (2 NaNO3 + H2SO4  Na2SO4 + 2 HNO3 ) or I can just add FeSO4 and conc. H2SO4? tnx

[igloo5080]

This test is not as commonly carried out these days as it was several decades ago owing to the potential hazards involved in using concentrated sulfuric acid. However it is a low risk experiment if proper precautions are taken and the instructions are adhered to.

Wear lab gloves and eye protection, of course.

Dissolve the metal nitrate in water, add a few crystals of FeSO₄, and shake or stir to dissolve.
Then, whilst holding the test tube at an angle of about 45^o, carefully pour a LITTLE concentrated sulfuric acid down the inside of the test-tube so that it forms a lower layer of no more than 5 mm. A brown ring will be formed between the layers.

You should Google this test to find out why it works and to find out also why the ring is transient and disappears when the mixture is shaken.

[Hybrid]

http://en.wikipedia.org/wiki/Nitrate_test#Brown_ring_test