RogueRose - 4-5-2016 at 16:47
I never noticed before that decomp of 2Ca(NO3)2 (starting at 500C) produces:
2CaO + 4NO2 + O2
Nitic Acid production is listed as the following:
3 NO2 + H2O → 2 HNO3 + NO
Or:
2 NO2 + H2O2 → 2 HNO3
As the decomp of the CalNitrate produces an extra O2, this is similar to using H2O2 instead of H2O as 2NO will combine with the extra O2 molecule to
produce 2(NO2).
If the gases from the decomp are bubbled through water, the O2 and NO will escape and most likely recombine above. Will this be absorbed on the
surface of the water or will it have to be bubbled back through the water/HNO3 solution?
Is this procedure sound or am I missing something.
It seems that Calcium nitrate may be one of the only common/commodity nitrates that allows for this decomp procedure as the rest don't seem to give a
clean NO2 from decomp.
[Edited on 5-5-2016 by RogueRose]
chemplayer... - 4-5-2016 at 19:14
If you have calcium nitrate couldn't you dissolve in water and then add an acid for which the corresponding calcium salt is insoluble? Then filter
this off and you've got nitric acid in solution. You could possibly distill this if you wanted then to get purer 68% azeotropic nitric acid.
You'd need to measure the reagents carefully to make sure they were stoichiometric and that you didn't end up with excess at the end.
Sulfuric is the obvious choice, but oxalic acid could also work well. Probably a few options.
clearly_not_atara - 4-5-2016 at 19:42
NO2 itself decomposes at 500 C, or rather exists in equilibrium with NO, so "cleanly" is not an accurate picture of the decomposition of calcium
nitrate or any other nitrate. Even so, producing a stream of NO2 at 500 C does not sound easy compared to the many simpler methods in the nitric acid
thread (which is worth checking out).