Electrolysis and Electroplating

2. 
The chemical and physical properties of elements
and compounds are exploited to make useful and/or
aesthetic products.
Describe and explain the purification of copper by
electrolysis, including a simple diagram of the cell.
Exam Objectives

3. 
Electroplating is used to
coat a thin layer of one
metal on top of another.
This can be done to protect
against corrosion, or to
improve the appearance of
an object. Sometimes a thin
layer of an expensive metal
can be coated onto a much
cheaper one.
Electroplating

4. 
In this situation, the part to be plated on is connected
to the negative terminal (cathode) and the metal you
wish to use for plating is the positive terminal
(anode)
A power supply supplies a direct current to the
anode, oxidizing the metal atoms that comprise it
and allowing them to dissolve in the solution.
At the cathode, the dissolved metal ions in the
electrolyte solution are reduced at the interface
between the solution and the cathode, such that they
"plate out" onto the cathode.
Nickel Plating of Copper

5. 
Electroplating copper –
acidified copper sulphate
solution with a copper
anode and cathode.
Technique would be used
to improve brass by plating
it with copper
You make electrode on to
which you want to deposit
copper the anode
Electroplating with copper

6. 
Cu
2+
(aq) + 2 e
-
 Cu(s) cathode
Cu(s)  Cu
2+
(aq) + 2 e
-
anode
Half-equations represent what is happening at each
electrode. In today’s practical, both electrodes
contained copper of some kind.
The cathode is so called because it attracts cations – it
is negatively charged
The anode attracts anions, making it positively
charged
Half-equations

7. 
C3.4_7c
C3.4_8b
Chemistry for you: Read from page 100
Answer questions 1-10 on page 116
Questions