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Electrorefining
Phyllis Zhang
Diana Gao
Cindy Zhang
Electrorefining
is the process of
purifying a
metal by
electrolysis.
-
Pure Cu
(Cathode)
DC power
supply
+
CuSO4(aq)
Slab of impure copper
containing such impurities
as: Zn, Pb, Ag(Anode)
Examine
the
following
cell
-
DC power
supply
Zn2+
Cu2+
Pure Cu
(Cathode)
+
Pb2+
Cu2+
CuSO4(aq)
Cu2+
Cu2+
Cu2+
Zn2+
2+
Cu
Cu2+
Cu, Zn, Pb, Ag
The cathode reaction:
The Cu2+ in solution is preferentially
reduced at the cathode but none of the
Pb2+ or Zn2+ can be reduced.(Cu2+
exists in larger amounts and has a
higher reduction potential than Zn2+
and Pb2+.)
In summary:
No metals above Cu on the table can
oxidize and go into solution, and no metal
below Cu on the chart can reduce and come
back out of solution. As a result, only Cu is
involved in both the oxidation and reduction.
Impure anode
pure cathode
Exercise----P246
An aqueous solution of SnSO4 was
electrolyzed using tin electrodes. The anode
contained a few percent of silver, copper and
zinc as impurities. Which substances(s) will be
oxidized at the anode? Which substances(s)
will be reduced at the cathode?
Applications
lead
copper
gold
silver
zinc
aluminium
chromium
cobalt
manganese
the rare-earth and alkali metals
Bibliography:
the video:
http://v.youku.com/v_show/id_XMjk5MDEwMTM2.html
the pictures:
http://image.baidu.com
information:
http://en.wikipedia.org/wiki/Electrorefining
That's all!
Thank you!
Zn
Pt
Cu
Ag
Pb
Au