Reaction of Copper with Nitric Acid

Water fountain turns a green solution to a beautiful blue color and makes the brown gas disappear.

Scientific name: Copper is oxidized consequently by concentrated nitric acid and interacts with water.


Reaction of copper with nitric acid

by Royal Society Of Chemistry

Copper Penny reacting with Nitric Acid

by ChemicalArts

Reactions of Copper with Dilute/Conc. Nitric Acid

by russellsuxs

Chemistry experiment 29 - Copper + nitric acid fountain

by koen2all

HD Chemistry-Copper Initiated Nitric Acid Fountain



Wear eye protection goggles and gloves. Concentrated nitric acid is corrosive and oxidising and should be handled with care. Nitrogen dioxide is toxic. Avoid its diffusion to air.Perform this experiment in a well ventilated room.

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reaction formula

Cu + 4HNO3 → Cu(NO3)2 + 2NO2 +H2O

Step-by-step instruction

WARNING! This experiment is dangerous! You should NOT perform this at home. ONLY carry out this experiment, if you are a trained chemist, and you understand local safety and legal requirements, which are required to perform such experiments

  1. Prepare a round-bottomed flask with thick walls, a conic flask and a gas delivery tube.
  2. Fill the round-bottomed flask with concentrated nitric acid.
  3. Pour water into the conic flask.
  4. Connect the vessels with a gas delivery tube. The end of the tube should touch the bottom of the conic flask.
  5. Put glass wool to the neck of the conic flask.
  6. Add the copper to the round-bottomed flask. Close it with a rubber stopper with a gas delivery tube.
  7. The solution turns green. The production of a brown gas is observed. When the reaction slows down and the gas is almost released, pressure in the system decreases. This leads to the water pouring back into the round-bottom flask. The brown gas dissolves.

Scientific background

This experiment demonstrates the reaction between copper and nitric acid:

Cu + 4HNO3 → Cu(NO3)2 + 2NO2 +H2O

At the first stage when copper reacts with concentrated nitric acid the metal ion coordinates with nitrate ions. This complex gives green color to the solution. The brown gas produced in the reaction is nitrogen dioxide. When water is added the solution becomes blue since nitrate ions are replaced by water molecules from the copper coordination shell. Nitrogen dioxide dissolves in the solution.


Published on 30 March 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst