Question

A shiny brown colored element ‘X’ on heating in the air becomes black in color. Name the element ‘X’ and the black colored compound.

Answer 1

1. We have a brown-colored element which on heating turned black. The given reaction is an oxidation reaction.
2. The oxidation reaction is the reaction in which the addition of oxygen occurs.
3. Here, when Copper(Cu) is heated in presence of oxygen, it gets oxidized to Copper (II)Oxide (CuO) and it is a black-colored substance.
4. Chemical reaction:

$$\begin{gathered} 2\mathrm{Cu}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2\mathrm{CuO}\left(\mathrm{s}\right) \\ \mathrm{Copper}\mathrm{oxygen}\mathrm{Copper}\left(\mathrm{II}\right)\mathrm{oxide} \end{gathered}$$

5. Hence, ‘X’ is copper and the black compound is copper (II)Oxide.