The action of sulfur dioxide on hydroxylamine (or hydroxylammonium salts) is a well known route to sulfamic acid.
(NH3OH2)2 SO4 + 2SO2 --> 2NH2SO3H + H2SO4
Is this reaction reversible in practice?
Every reaction step is reversible, but the equilibrium constant can be anything from near zero to near infinity. And consider also that the majority
of reactions take course in a series of reaction steps, each having its own equilibrium! For this reason, it is unreasonable to expect a redox
reaction like this one, with the two sides thermodynamically so extremely far apart, to possibly be reversible in any of the common sense of this
term. Paradoxically however, it is "in principle" reversible, but nothing more than that. That's why the reversibility is a an arbitrary concept. When
evaluating reversibility, all you need to do, is ask yourself: "Can the reversibility of the reaction, under any circumstances whatsoever, affect any
of the observable results?"
Hydrolysis of sulfamic acid will give you ammonium bisulfate. Hydroxylamine can be made by reacting sulfur dioxide with potassium nitrite to produce
potassium hydroxylamine disulfonate (which crystallizes; adding extra potassium salts increases yield through the common-ion effect). The resulting
salt is then hydrolyzed to produce hydroxylamine sulfate. Take a look at Brauer's amazing handbook of inorganic recipes in the Sciencemadness library
for more hydroxylamine chemistry.
