Question

why will the colour of copper powder become black when air is passed over it?

Answer 1

The colour of copper powder change into black substance because the reaction 2cu plus O2 ----- 2cuO( black)

Answer 2

▶️ANSWER◀️

When air is passed over copper powder, it reacts with oxygen present in the air. Oxygen is added to copper powder and copper oxide is formed. Hence the colour of copper powder changes to brown.

2Cu + O2 -----> 2CuO

(Brown) (Black)