Make Nitric Acid - The Complete Guide

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• published: 04 Jun 2009
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We show 3 ways to make nitric acid based on two different chemical approaches both of which can be done using easily accessible materials. Warning: The procedures in this video produce large quantities of toxic gases and deal with highly corrosive acids. All work must be performed in a fume hood with proper safety equipment. And all apparatus must be glass to withstand the acids. Chemically, nitric acid is made by bubbling nitrogen dioxide into water. So the objective in this approach is to generate nitrogen dioxide. This can be done by reacting hydrochloric acid, a nitrate salt and copper. Around 80grams of sodium nitrate, over 30 grams of copper and 100mL of hydrochloric acid (37% 12M) are the quantities needed. The exact amount isn't critical. For usable concentrations, the amount of water being converted should be small, around 20-50mL. Any source of nitrate is usable including potassium nitrate, ammonium nitrate and even nitrate-based fertilizers. You can use our previous video on testing for nitrates if you want to determine if yours can be used. http://www.youtube.com/watch?v=f5M3rUqaEYs The tricky part now is leading the gas into water. Two approaches are shown in the video. In the first approach three containers, such as jars are place inside each other to force the gas to go into the water. This is very inefficient but is very simple to do. The better approach is to lead the gas out of the generator through a tube and into a chilled container of water. The water that's converted into nitric acid can be replaced with hydrogen peroxide for better yield. The chemical waste that's generated contains the valuable copper used before and recovering it is worthwhile due to todays high copper prices. This is simply done by putting in enough aluminum metal that it reacts with all the acids and copper in solution to create a slurry of copper. This can be filtered to obtain a residue of copper. Its highly contaminated but can still be used to make more nitric acid. For further information on the chemistry type "copper and nitric acid" into google. The hydrochloric acid and nitrate salt behave as nitric acid (with nitrate from the salt and protons from the hydrochloric acid) and dissolve the copper releasing nitrogen dioxide gas. You can use other concentrations of hydrochloric acid but you need to decrease the amount of water added to keep the concentrations the same. Finally, the last way of making pure nitric acid is to react concentrated sulfuric acid and a pure nitrate salt (NOT fertilizer) and heat it in a glass distillation apparatus to distill over the pure nitric acid. Stoichiometric quantities of both reagents are recommended for maximum yield. We get our glassware from chemglass or VWR