4 HNO3 + Cu → 2 H2O + 2 NO2 + Cu[NO3]2
This is a complexation reaction: Cu[NO3]2 is the formed complex.
This is an oxidation-reduction (redox) reaction:
Cu0 - 2 e- → CuII (oxidation)
2 NV + 2 e- → 2 NIV (reduction)
Cu is a reducing agent, HNO3 is an oxidizing agent.
- HNO3 – Nitric acid
- Other names: Aqua fortis , Spirit of niter , Eau forte
- Appearance: Colorless, yellow or red fuming liquid ; Colourless-to-yellow liquid with pungent odour ; Colorless, yellow, or red, fuming liquid with an acrid, suffocating odor. [Note: Often used in an aqueous solution. Fuming nitric acid is concentrated nitric acid that contains dissolved nitrogen dioxide.]
- H2O – Water, oxidane
- NO2 – Nitrogen dioxide
- Other names: Nitrogen(IV) oxide , Deutoxide of nitrogen , Nitrogen peroxide
- Appearance: Brown gas ; Reddish-brown gas or brown or yellow liquid with pungent odour ; Yellowish-brown liquid or reddish-brown gas (above 70°F) with a pungent, acrid odor. [Note: In solid form (below 15°F) it is found structurally as N2O4.]