Sodium hyponitrite, decomposition

Sodium hyponitrite is readily soluble in water, the concentrated solution being stable in presence of a large proportion of sodium hydroxide. On crystallization the salt is deposited as pentahydrate, this substance losing its water of crystallization in a desiccator or on exposure to air. The anhydrous salt is the more stable form it melts with decomposition at 300° C. The cryoscopic method gives the double molecular formula, Na2N202. 

The action of sodium on ammonium nitrate results in a violent explosion. It is assumed to be caused by the decomposition of a hyponitrite formed as follows ... 

Amorphous sodium rrans-hyponitrite (NajNjOj), heated in a DSC in the absence of oxygen, decomposed [72] suddenly at various temperatures between 633 and 663 K with the formation of a viscous froth that later changed to a white residual solid. The reaction (NajNjOj NajO + NjO) may be accompanied by the formation of nitrite (NajNjOj + Oj — 2NaN02) and further oxidation to nitrate due to breakdown of NjO to oxygen by an unidentified mechanism. When Na2N202 is heated in oxygen the decomposition temperature is lowered by oxidation of N202 to N02 and subsequently to NOj. ... 

Hyponitrous acid—H3N4O3—31—Known only in combination. Silver hyponitrite is formed by reduction of sodium nitrate by nascent H and decomposition with silver nitrate. 

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