When heated in air, brown copper powder turns black. This black powder would turn brown again when heated with

Question

When heated in air, brown copper powder turns black. This black powder would turn brown again when heated with (A) CO (B) O2 (C) H2 (D) NH3

Tardigrade Admin · Accepted Answer

When heated in air, brown copper turns black. This black powder would turn brown again when heated with hydrogen

(H_{2})

. This is because here,

H_{2}

will act as air reducing agent that reduces

C u O

into

C u

, whereas air

(O_{2})

will act as an oxidising agent.

Brown C u + O_{2} Δ Black C u O

Black C u O + H_{2} Δ C u + H_{2} O

Q. When heated in air, brown copper powder turns black. This black powder would turn brown again when heated with