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Environmental fate & pathways

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Sodium cyanide is highly soluble in water, forming sodium ion and free cyanide. The pKa of sodium cyanide is 9.36 at 20 degrees C; it is hydrated to hydrogen cyanide under circumneutral conditions. Hydrolysis of HCN, to formic acid and ammonia, is normally a very slow reaction and it does not play a role under natural environmental conditions.

Photolysis of hydrogen cyanide may occur in the presence of hydroxyl ions in the atmsophere. The range of half-life values for photo-oxidation (not including oceanic uptake) is 0.06 years to 11 years. Photolysis in water may be an important process for iron cyanide complexes, depending on the penetration of UV and visible light.