Making Fuming Nitric Acid

Warning: This experiment deals with dangerous and toxic chemicals.

Fuming nitric acid is defined as having a concentration of HNO3 greater than 86%. This is much higher than the conventional 68% of common lab nitric acid.

The reaction between the nitric acid and the nitrile and latex gloves is extremely exothermic and violent. It is often recommended to avoid using gloves altogether when working with fuming nitric acid unless resistant gloves are available (e.g. butyl rubber gloves or Ansell brand laminated film gloves which were suggested by user Atomosphysica). Regular concentrated nitric acid is still not good to use with latex gloves. Latex offers little to no protection. Nitric acid can quickly penetrate the glove and then irritate skin.

Fuming nitric acid is not nearly as common and it is used in much fewer reactions. For example, for the synthesis of high explosives. The high concentration of HNO3 is required in order to nitrate a molecule several times. For example, TNT, or tri-nitrotuluene, is prepared using fuming nitric acid. It is possible to di-nitrate it using concentrated nitric acid, but the third nitration is unlikely to occur, so yield will be zero or uselessly low.