Question

When Copper powder is heated in a china dish the surface of the copper powder becomes coated with a black colour substance. Why has this black-coloured substance formed? What is that black substance? Write the chemical equation of the reaction.

Answer 1

Oxidation:

• “The reaction in which oxygen is added or hydrogen is removed is called oxidation.”
• The heating of metal in the air results in oxidation.

Heating Copper in a China dish:

• If the Copper powder is heated in a china dish, it reacts with oxygen present in the air to form Copper ($\mathrm{II}$) oxide which is black in colour.
• The black colour is produced due to the oxidation of Copper.

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