5. Solid copper is added to a dilute nitric acid solution.

When solid copper is added to a dilute solution of nitric acid (HNO₃), a chemical reaction occurs in which the copper metal is oxidized and the nitric acid is reduced. The products of the reaction are copper nitrate (Cu(NO₃)₂), water (H₂O), and nitrogen oxides such as nitrogen dioxide (NO₂), which is a gas that appears as a brown fume.

The equation for this reaction can vary depending on the concentration of nitric acid and other conditions, but a possible reaction with dilute nitric acid might be represented by the following equation:

3 Cu(s) + 8 HNO₃(aq) → 3 Cu(NO₃)₂(aq) + 2 NO(g) + 4 H₂O(l)

In this reaction: - 3 atoms of copper (Cu) react with 8 molecules of nitric acid (HNO₃). - Copper (Cu) gets oxidized to copper (II) nitrate (Cu(NO₃)₂). - Nitric acid (HNO₃) gets reduced to nitrogen monoxide (NO), which can further react with oxygen in the air to form nitrogen dioxide (NO₂). - Water (H₂O) is also formed as a byproduct of the reaction.

Please note that this is a simplified version of the reaction, and the actual oxidation state of nitrogen in the nitrogen oxides produced can vary. Nitrogen dioxide is a toxic brown gas, and appropriate safety measures should be taken when conducting this reaction.C