Question

when copper powder is heated is a China dish the surface of copper powder become coated with black colour substance first what is this black substance second why has a black coloured substance formed third 9 the chemical equation of above reaction

Answer 1

1) the black colour substance is formed by the reaction of copper with oxygen.

 

2)the black colouresd substance is CuO(copper(ii) oxide)

3)the chemical equation for the reaction is ----

2Cu + O2 -----> 2CuO

Answer 2

When the “copper powder” is heated in a ‘china dish’, the copper powder surface becomes coated with “black colour substance” due to the formation of ‘copper oxide’ by surface oxidation.

EXPLANATION:

Copper reacts with oxygen in the air upon heating and forms copper oxide. The black colour is due to the formation of this copper (II) oxide.

The copper oxide thus formed can be reduced to its basic metal form by reducing it with hydrogen or carbon monoxide.  

The equation of ‘copper (II) oxide’ formation is:  

$\bold{2 C u(s)+O_{2}(g) \rightarrow 2 C u O(s)}$