Editing Nitric acid (section)

===Anhydrous nitric acid===
White fuming nitric acid, pure nitric acid or WFNA, is very close to anhydrous nitric acid. It is available as 99.9% nitric acid by assay, or about 24&nbsp;[[molarity|molar]]. One specification for white fuming nitric acid is that it has a maximum of 2% water and a maximum of 0.5% dissolved {{chem2|NO2}}. [[Anhydrous]] nitric acid is a colorless, low-[[viscosity]] (mobile) liquid with a density of 1.512&ndash;3&nbsp;g/cm<sup>3</sup> that solidifies at {{convert|-42|C}} to form white crystals.<ref>{{cite web |url=https://www.sigmaaldrich.com/US/en/product/mm/100455 |title=Nitric acid fuming 100% |publisher=Sigma-Aldrich |access-date=May 15, 2025}}</ref> Its dynamic viscosity under standard conditions is 0.76&nbsp;mPa·s.<ref>[https://www.wolframalpha.com/input?i=nitric+acid+viscosity "nitric acid viscosity"]. Wolfram Alpha Knowledgebase (2002). Champaign, Illinois.</ref> As it decomposes to {{chem2|NO2}} and water, it obtains a yellow tint. It boils at {{convert|83|C}}. It is usually stored in a glass shatterproof amber bottle with twice the volume of head space to allow for pressure build up, but even with those precautions the bottle must be vented monthly to release pressure.