Question

You might have noted that when copper powder is heated in a china dish, the surface of copper powder becomes coated with a black colour substance. 

(a) How has this black coloured substance formed? 

(b) What is that black substance? 

(c) Write the chemical equation of the reaction that takes place.

Answer 1

(a) When copper powder is heated in the presence of air (oxygen), cooper reacts with oxygen to form copper oxide. The copper oxide formed is black in colour. The black colour is formed because the oxidation of copper takes place. 

(b) The black substance formed is copper oxide. 

(c) The chemical equation of the reaction that takes place is given below:

2Cu + O₂→ 2CuO