Sciencemadness Discussion Board

HNO3 from NaNO2!

SAM4CH - 20-3-2005 at 09:56

I try to get NO2 from NaNO3 + H2SO4 and I belive it works, Now how to get HNO3 from NaNO2 with high efficiency home system!?

12AX7 - 20-3-2005 at 11:18

Umm... no? 2NaNO2 + H2SO4 > Na2SO4 + 2HNO2 (nitrous acid) which probably decomposes easily yielding OH + NO, hm there's an extra oxygen in there, that's kind of confusing.

Electrolysis might do it... molten NaNO2 + electrons = Na metal + NO2 gas, bubble gas through water.

Tim

neutrino - 20-3-2005 at 12:04

2H<sup>+</sup> + 2 NO<sub>2</sub><sup>-</sup> -> H<sub>2</sub>O + NO + NO<sub>2</sub>

2NO + O<sub>2</sub> -> 2NO<sub>2</sub>

3NO<sub>2</sub> + H<sub>2</sub>O -> 2HNO<sub>3</sub> + NO

garage chemist - 20-3-2005 at 12:12

When acid is added to a nitrite, the resulting HNO2 decomposes as follows:

2 HNO2 ---> NO + NO2 + H2O

(NO2 only escapes if no water is present. With dilute nitrite solutions, only NO is produced.)
The resulting NO + NO2 is in equilibrium with N2O3.
To make N2O3, conc. H2SO4 is added to a nitrite.

This also offers a method for "purifying" sodium nitrite: conc. H2SO4 is added to the nitrite + nitrate mix obtained by reduction of NaNO3 with lead, the resulting N2O3 is led into NaOH soln where it forms pure nitrite.

I see no point in making HNO3 from nitrite, as it would require conc. H2SO4, which you can just mix with the much cheaper NaNO3 and (after distillation) get HNO3 much easier.

12AX7 - 20-3-2005 at 15:40

Ah, so N2O3 (or the likewise mixture of NO and NO2) is the acid gas of nitrite ion? Does that mean straight NO in water (if soluble) would be hyponitrous acid?

Tim

vulture - 21-3-2005 at 04:23

Making HNO3 from NaNO2 is a terrible waste. You should slap yourself for wasting something valuable on something common. YES, nitric acid is VERY common if you use your brain.

hodges - 21-3-2005 at 14:52

I guess theoretically one could use nitrites to create nitric acid without the need for distilling. However, the aparatus needed would be no less complicated than a distilling setup. This would also work if one only had access to dilute acids and not concentrated H2SO4.