The reaction of copper heated in air is a bit more complex than a simple single equation. It involves several steps and depends on the temperature.

Here's a breakdown:

At lower temperatures (below about 600°C):

* Copper oxide formation: Copper reacts with oxygen to form copper(I) oxide (Cu₂O):

2Cu(s) + O₂(g) → 2Cu₂O(s)

* Further oxidation: Copper(I) oxide can further oxidize to copper(II) oxide (CuO):

2Cu₂O(s) + O₂(g) → 4CuO(s)

At higher temperatures (above 600°C):

* Copper(II) oxide formation: The reaction directly forms copper(II) oxide:

Cu(s) + 1/2 O₂(g) → CuO(s)

Overall:

The overall reaction, taking into account the various stages, can be summarized as:

2Cu(s) + O₂(g) → 2CuO(s)

This equation represents the formation of copper(II) oxide as the primary product. However, it's important to remember that the reaction is more complex and involves various intermediate steps.