Animated video: 37 principles of chemical reactions and their dangers – Copper and nitric acid

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Principle: Copper reacts with concentrated nitric acid to produce copper nitrate, nitrogen dioxide, and water. The gas generated is introduced into water; as its production stops and it gradually dissolves, water is drawn into the reaction vessel, ultimately resulting in a pale blue solution of copper nitrate. Cu(s) + 4HNO3(aq) → Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l). The green color that appears at first is due to the combination of copper ions and nitrate ions under concentrated acid conditions; once more water is added, the solution takes on the blue color characteristic of hydrated copper ions. Fun fact: Copper and concentrated nitric acid are probably the most difficult high school chemistry reactions to memorize... wait, there’s also dilute nitric acid. Do you still remember how to balance it? Recorder: Royal Society of Chemistry. Hazard: Medium; concentrated nitric acid is highly corrosive, so the use of gloves and goggles is recommended. Nitrogen dioxide gas is toxic, but in this experiment most of the gas produced will be absorbed by water. The “fountain” effect caused by the suction in the latter half poses a lower risk of damaging the flask; if it is carried out in an open laboratory, a safety screen should be used to protect the observers.