Chromatography Forum

Not quit the right forum, but it's a question where I need experienced chemist's.

I've got a beaker with a solution, most probably nitric acid, but I don't know that for sure. Is there a very simple way te prove that it is concentrated sulfuric acid and not some other acid or just water.

For pH you can use pH-paper and there is a substance that turn's blue with water and now I'm looking for something like that to prove that it is nitric acid (or not).

I hope you have some great idear's. Thanks!

Jorim

Jorim,

You might dilute a small amount with water and prove that it is acidic first (remember to add the acid to the water and no the other way around). Then take some of the diluted acid and add some barium chloride. If the acid is sulfuric you will get a nice white ppt. of barium sulfate. If the acid is nitric or hydrochloric there will be not ppt formed.

Just a suggestion for a place to start.

Regards,
Mark

Thanks for your reply Mark, but I made a terrible translation mistake. It must be nitric acid and not sulphuric acid.

Same story thus, but with nitric acid...

Jorim

Somebody ???

if you are sure, its concentrated acid, cant you use its melting point?

If you are sure that it is concentrated acid, than that's possible, but you don't no of it is concentrated. With a pH-measering you can prove that it is acidic, but nothing more.

We used to throw a penny (copper) into con HNO3 and got a brown gas (N-oxides). If you dilute it you can do some color test, can´t recall the details, but any book (first year college text) on qualitative analysis should have this.
(dangerous, so should only be done with small amts: If con H2SO4 is dripped into con HNO3 one may also get brown gases).

Don't you also get brown NOx gasses if it is HNO2 (don't know the name in English) instead of HNO3 ???

If you dilute it you can do some color test, can´t recall the details, but any book (first year college text) on qualitative analysis should have this.

Not my Dutch books, but color tests would be very nice...

Small tip for the administrator(s): overhere

HNO2????
Merck might have some color test.

HNO2????

Yes nitrous acid, don't that give also brown NOx gasses.

I've searched the internet (also merck's sites, I don't have there index overhere, if you meant that...) for color tests for nitric acid and can't find anything. If you can give me an example or an url would that be very very nice...

HNO2 is not stable in concentrated solution. Therefore if you make the penny test and get brown gases it is most probable nitric acid. To exclude HCl you may test with silver nitrate (white precipitation).

Checking the catalog of Merck, Darmstadt I found for
general nitrate tests the catalog # 1.11170.0001 and 1.11169.0001
or for nitrate in water testing (Merckoquant) catalog # 1.10050.0001
and 1.10020.0001

The catalog gave, for internet ordering: www.labshop.de
or www.vwr.com

Whether this cooperation between Merck and VWR still exists is not clear, so there might be some trouple. Merck Sharp and Dohme (apparently connected with the Merck index?) is a different firm (for the case that you need a further internet search).

Another option, if you have a UV spectrophotometer is to see the absorbance of your solution in low wavelength. NO3- absorbs at low wavelengths (i.e. 210 nm) unlike other acids like SO4-, PO4- Cl- etc...

HMW, VMR is still distributer of Merck products, at least in the USA.