What will happen to the reaction in the reduction of copper(II)oxide?

Question

What might happen if the natural gas supply passing over the copper oxide is turned off a few minutes before the external heat is turned off? This is an experiment regarding the reduction of copper(II)oxide.

Answer 1

If the copper(II) oxide is in a sealed system, then nothing will happen.  If it is open to the air, any copper metal or copper(I) oxide that is formed in the reduction would be exposed to air while still hot, and could oxidize back to copper(II) oxide.