Final answer:
B) Oxidation of copper
When HNO₂ is mixed with dissolved copper, it results in the oxidation of copper. This is a redox reaction where copper is oxidized and nitric acid is reduced to NO gas, which can be represented by balanced half-reactions.
Step-by-step explanation:
When HNO₂ (nitrous acid) is mixed with dissolved copper, it will cause the oxidation of copper (Cu). Copper reacts with both dilute and concentrated nitric acid, but the products of the reactions are different. With dilute nitric acid, copper produces copper ions (Cu²⁺) and a NO gas. The process can be described by the reactions:
oxidation:
Cu(s) → Cu²⁺ (aq) + 2e⁻
reduction:
3H⁺₊(aq) + HNO₃(aq) → NO(g) + 2H₂O(ℓ)
In the redox (reduction-oxidation) process, the copper is oxidized and nitric acid acts as the oxidizing agent, being reduced to NO in the process. This is supported by the given balanced half-reactions, where we see copper going from an oxidation state of 0 to +2 and the nitrate ion being reduced to NO gas.