In order to test if the final product is/contains HNO3, it shall be placed in a container containing a bit of copper oxide that I've previously made
in another experiment.
Procedure:
A small amount of NH4NO3 was added to a test tube with a small amount of water. I then took all of my materials outside for safety reasons. Then, a
few drops of HCl was added to the test tube. I noticed that the previously white solution had gained a yellowish tinge and appeared grainy, and a very
small amount of white smoke was seen only at the top of the tube, but then quickly dissipated. There appeared to be no change in heat of the mixture.
In a separate glass cup, I added the copper oxide and then poured the contents of the test tube into it as well. The contents slowly became a very
slight greenish-yellow color. A very faint odor was noted, which had reminded me of H2S.
I then proceeded to neutralize everything that came in contact with the solution and the dropper with a solution of baking soda, water, and dish soap.
To my surprise, not a lot of (if any) fizzing occurred, BUT some of the white smoke described previously was seen very briefly flowing from the now
neutralized containers. From my observations, I would guess that the gas could be N2O, but I could not say for sure.
Conclusion: The final product did not appear to be HNO3. I don't really have an idea of what it could be, but maybe a solution of
NH4Cl. This is my first time actually fully recording a home experiment of my own; any advice or suggestions for future experiments would be welcome
and greatly appreciated.
[Edited on 8/21/2015 by Velzee]Bert - 20-8-2015 at 19:07
You probably made a bit of nitrosyl chloride and some chlorine. I hope you were using a fume hood, or were outdoors and worked with the wind at your
back. You can't use hydrochloric acid to produce nitric acid from a nitrate salt- Use sulfuric acid instead.
Funny to read that according to your observations the gas might be N2O. How can you see that? Because of white fumes? I am interested in your
thought-process.
What happens is the following:
- You add conc. HCl to a concentrated solution of NH4NO3. This leads to formation of solid NH4Cl. The latter is less soluble than NH4NO3. The
formation of the solid explains the graininess of your liquid. Not all chloride, however, precipitates as NH4Cl. In your solution, quite some chloride
remains.
- Your solution contains NH4(+), NO3(-), Cl(-) and H(+) ions, all of these of course hydrated.
- The white fume you see most likely is from the hydrochloric acid, it is HCl, dissolved in very fine droplets of water, extracted from humidity in
the air.
- The yellow color is due to formation of a mix of nitrosylchloride (ONCl) and chlorine. These compounds are formed slowly.
- Cl2 and ONCl in turn can react with ammonium ions, leading to formation of NCl3 and N2. These reactions, however, are incomplete and slow at the
conditions of your experiment, so there is no need to fear explosions.
Mixing NH4NO3 and conc. HCl is not a useful method for making HNO3. The chloride ions simply interfere too strongly and break down the nitrate ions.
In fact, by mixing these chemicals you make a version of "poor man's aqua regia"
.
Bert is absolutely right with his comment. Use sulphuric acid instead of hydrochloric acid.ave369 - 21-8-2015 at 05:58
And also do not use ammonium nitrate, use some real metal instead. Ammonium can produce some undesirable side reactions. Use KNO3, NaNO3 or Ca (NO3)2.
If you have a distillation setup, the first two can be used, this is Glauber's classic reaction. If you don't, use calcium nitrate, but be prepared to
get rid of the incredibly voluminous and messy precipitate of CaSO4.
[Edited on 21-8-2015 by ave369]CharlieA - 21-8-2015 at 06:12
How can so many concrete conclusions be drawn from an experiment where no quantities or amounts are given?
A small amount? A few drops? Concentrations?
[Edited on 8-21-2015 by CharlieA]szuko03 - 21-8-2015 at 07:07
^ ... by knowing whats going into the system you can predict the outcome based on previous observations. You dont need to know how much to make a
general chemical equation sure it may not be balanced and you would have to adjust it to do that but surely you are not meaning to say you cant tell
what products would be produced without knowing the mass of the reactants.
I knew scientists take things literally but god damn just because no amounts were given doesnt mean 0g were used or something. Takes just a little bit
of creative thinking Velzee - 21-8-2015 at 07:13
Funny to read that according to your observations the gas might be N2O. How can you see that? Because of white fumes? I am interested in your
thought-process.
I attempted to synthesize N2O a while back by slowly heating a small amount of NH4NO3 in a test tube. What had resulted was a white vapor, very
similar to the gas I saw while performing this experiment. In the N2O experiment, the vapor just "smelled" or felt like normal water vapor. I decided
end the experiment early, because the NH4NO3 became a brownish color, and wasn't leaving behind a clean test tube as it was expected to.
Quote:
by mixing these chemicals you make a version of "poor man's aqua regia"
xD That's kind of what I was trying to do.
Quote:
A few drops? Concentrations?
I believe the concentration of the HCl was ~35-37%, and I do not know the purity of the NH4NO3; I obtained it from an ice pack(I filtered and then
recrystallized the NH4NO3). All amounts were relatively small—I admit that I wasn't keeping a good measure of everything.
[Edited on 8/21/2015 by Velzee]woelen - 21-8-2015 at 11:27
The white vapor you had when heating NH4NO3 was water vapor: NH4NO3 --> N2O + 2 H2O
N2O is invisible, you simply cannot see colorless gases.
The brown stuff which remained behind when heating your NH4NO3 is due to impurities, most likely some organic material which discolors or chars on
heating.
.