Quoted By:
theoretically? no. Practically, you need water in it if you plan on isolating the nitric acid and don't want to go from a medium-difficulty setup to a high-difficulty setup. 98% sulfuric with dry nitrate salt in stoichiometric ratio will generally start to form an insoluble crud of the sulfate salt as you distill off nitric acid, which hinders even heating/mixing as your distillation progresses. If you add enough water for azeotropic nitric acid to come off at around 37%, your distillation flask should stay liquid the full time. You also need to worry about thermal decomposition of the nitric acid if there is no water around, it will decompose into lots of nitrogen oxides and you'll lose a lot of yield without water around to stabilize it and sap up the heat it takes to boil the nitric acid in the first place. Lastly, if you go without water you'll be distilling off pure nitric acid which is a pain to handle as it's volatile and generally eats through everything instantly. Very few cases where you need pure nitric acid relative to the 37% azeotrope which is good for 90% of nitrations.
