When heated in air,brown copper powder turns | vedclass

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Question

(C) The correct option is $C$.When copper powder is heated in air,it reacts with oxygen to form copper$(II)$ oxide,which is black in color: $2Cu(s) +

Vedclass · Accepted Answer

$H_{2}$

Vedclass · Answer

(C) The correct option is $C$.When copper powder is heated in air,it reacts with oxygen to form copper$(II)$ oxide,which is black in color: $2Cu(s) + O_{2}(g) \stackrel{\Delta}{\longrightarrow} 2CuO(s)$ (Black).When this black copper$(II)$ oxide is heated with hydrogen gas $(H_{2})$,it undergoes a reduction reaction to form copper metal,which is brown in color: $CuO(s) + H_{2}(g) \stackrel{\Delta}{\longrightarrow} Cu(s) + H_{2}O(g)$.Thus,$H_{2}$ acts as a reducing agent to convert the black oxide back into brown copper.

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

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