Which fo the following is true for the following reaction ?
`2 Cu_2 O(s)+Cu_(2)S(s) rarr 6 Cu (s) + SO_2 (g)`.

Options

A. It is a redox reaction.
B. `Cu_2O` is an oxidant
C. `Cu_2S ` is a reductant.
D. All of these

Answer

D

Explanation

Assign oxidation number to each of the species in the reaction under examination:
`overset (+1) (2Cu_2) overset (-2)(O)(s) + overset (+1) (Cu_2) overset(-2) (S) (s) rarr overset(0) (6Cu)(s) + overset(+4-2) (SO_2)`
We can notice that in this reaction, copper is reduced from ` +1` state to zero oxidation state while sulfur is oxidized from `-2` state to ` +4` state. Thus, the above reaction is a redox reaction.
`Cu_2O` helps sulfur in ` Cu_2S` to increase its oxidation number. Thus, ` Cu(I)` in ` Cu_2O` is an oxidant. Sulphur of ` Cu_2S` helps copper (in ` Cu_2 S` itself and ` Cu_2O`) to decrease its oxidation number. Thus sulfur of ` Cu_2 S` is a reductant .