This evening I went looking at my NH4NO2 solution and see what remains of this. All water now has evaporated and there is a very small amount of solid
left. The funny thing is, the solid forms a very thin layer and this layer has the shape of bubbles. I added a small amount of water to the solid and
the solid does not dissolve quickly. Next, I added a small amount of dilute H2SO4 and when this is done, no visible reaction occurs. The air above the
solid becomes very pale brown, it is just visible, and there is the smell of NO2, unmistakenly, but weak.
So, the conclusion of my experiment is that making solid NH4NO2 from a solution of NH4NO2 in water is not possible. The material decomposes on
evaporation of the water. The remaining solid must be KClO4 and/or NH4ClO4, remaining from the perchlorate added. Traces of nitrite were still left in
the solid, but not more than traces.
So, in this case the books are right. NH4NO2 cannot be prepared from aqueous solution, it decomposes to water and N2 when the solution is allowed to
evaporate. |