nitric acid
A corrosive, non-volatile, inorganic acid (HNO
3 ). It is a strong acid, with most of
its important reactions being due to its oxidizing
action. Nitric acid reacts violently with
cellulosic materials, and can be formed in them by
the conversion of nitric oxide (an air pollutant)
into nitrogen dioxide, and then into nitric acid:
2NO + O 2 → 2NO 2 ;
3NO 2 + H 2 O → 2HNO
3 + NO.
As the amount of nitric oxide in the atmosphere is
very small, relative to sulfur dioxide, the
formation of nitric acid in archival materials is
relatively slow; however, it also functions as a
catalyst in the conversion of sulfur dioxide into
sulfuric acid.
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