The displacement of
metals from solution is a redox reaction. In general,
a more reactive metal will displace a less reactive
metal from a solution of its ions.
One common displacement
reaction in qualitative analysis is the displacement
of copper from a solution of copper(II) salt by zinc
metal:
Zn (s) + CuSO4
(aq) -----> ZnSO4
(aq) + Cu (s)
Zinc displaces copper from
the solution because it is more reactive than copper
metal. Zinc, being more reactive, loses its electrons
readily. The electrons are transferred from the zinc
atoms to the copper(II) ions in the solution. Copper(II)
ions are reduced to copper metal and zinc atoms become
oxidised to zinc ions.
Oxidation reaction: Zn
(s) -----> Zn2+
(aq) + 2e-
Reduction reaction: Cu2+
(aq)
+ 2e- -----> Cu (s)
Overall Redox reaction:
Zn (s) + Cu2+
(aq) -----> Zn2+
(aq) + Cu (s)
