Lesson Slides : Experiments from Chapter 4 Electrochemistry

1. Experiment 6.3
TO INVESTIGATE THE EFFECT OF SPECIFIC
ELECTRODES ON THE ELECTROLYTIC PROCESS OF
AN ELECTROLYSIS
When a specific electrode is used in the electrolysis of an
electrolyte, the electrolytic process may change.

2. PROCEDURE
1. Clean the carbon electrodes
with sandpaper.
2. Weight the anode and
cathode individually.
3. Set-up the apparatus as
shown in figure.
4. Turn on the switch for 15
minutes.
5. Take out the anode, wash it,
dry it and the weigh it.
6. Record the observations.
Carbon Carbon
Figure (a)
A

3. PROCEDURE
7. Repeat step 1-6 using
copper electrodes to
replace carbon
electrodes as shown in
figure (b).
8. Record all readings and
observations.
Copper Copper
Figure (b)
A

4. DATA AND OBSERVATION
Electrode Observation Mass of the anode (g)
Before After
Carbon
Copper

5. EXPERIMENT 6.5
TO STUDY THE ELECTROPLATING OF AN OBJECT
WITH COPPER
Electroplating provides a thin protective coating of
metal on the surface of another metal. The thin
coating makes the electroplated object
more attractive and resistant to corrosion.

6. Copper
1.Clean a piece of iron nail
with sandpaper
2.Set up the apparatus using
a copper strip as a cathode
and iron as the anode.
3.Turn on the switch.
4.Record all observations.
5.Repeat step 1-3 by
interchanging the position
of iron and copper strip.

7. DATA AND OBSERVATION
Set Electrode Observation
Anode Cathode Anode Cathode
I Iron Copper
II Copper Iron

8. EXPERIMENT 6.6
TO SHOW THE PRODUCTION OF ELECTRICITY FROM
CHEMICAL REACTIONS IN A SIMPLE VOLTAIC CELL
Electrical energy can be generated from chemical reactions in
a simple voltaic cell. A voltaic cell is also called galvanic cell. It
consists of two metals dipped into an electrolyte and connected
by wires. Electricity is the movement of electrons that is
produced when there is a difference in electrical potential
between two points connected by a conductor.

9. PROCEDURE
1. Clean a piece of Magnesium
ribbon and Copper plate
with sandpaper.
2. Fill in the beaker with 1 mol
dm-3 sodium chloride, NaCl.
3. Set-up the apparatus as
shown in figure.
4. Record the reading at the
voltmeter and the changes
at the electrodes.
5. Repeat Steps 1-5 using
another copper plate to
replace the Magnesium
ribbon.
Magnesium
ribbon
Copper
plate
Figure (a)
V
Sodium
chloride, NaCl
solution

10. DATA AND OBSERVATION
Type of
Metal
Voltmeter
reading (V)
Observation
Magnesium/
Copper
Copper/
Copper

11. EXPERIMENT 6.7
TO CONSTRUCT THE ELECTROCHEMICAL SERIES BASED ON
POTENTIAL DIFFERENCES BETWEEN METALS
Atoms of different metals have different tendencies to donate electrons. When
two different metals are dipped into an electrolyte, the more electropositive metal
will donate electrons first.
(more electropositive = greater tendency to donate electrons) The more
electropositive metal will become the negative terminal (anode)

12. PROCEDURE
1. Clean the metals with sandpaper.
2. Fill a beaker with dilute sulphuric
acid, H2SO4 .
3. Dip the Magnesium strip as
Electrode A and Copper strip, as
Electrode B into dilute sulphuric acid.
4. Connect the circuit.
5. Record the potential difference
between the metals.
6. Determine and record which metal
strip is the negative terminal
(anode).
7. Repeat Steps 1-6 using other
metals to replace Magnesium as
Electrode A
Electrode A,
Magnesium
Electrode B,
Copper
Figure (a)
V
Dilute
sulphuric acid,
H2SO4

13. DATA AND OBSERVATION
Pair of electrodes
Potential
Difference (V)
Negative terminal
of the cell
Magnesium and Copper
Aluminium and Copper
Zinc and Copper
Lead and Copper
Iron and Copper

14. EXPERIMENT 6.8
TO CONSTRUCT THE ELECTROCHEMICAL SERIES
BASED ON THE PRINCIPLE OF DISPLACEMENT OF
METALS
The displacement reaction is a chemical change which takes
place when a metal placed higher in the Electrochemical
Series displaces a metal below it from its salt solution.

15. 1. Pour 3 mLof magnesium nitrate, Mg(NO3)2 solution, zinc nitrate, Zn(NO3)2 solution,
lead(II) nitrate, Pb(NO3)2 solution and copper(II) nitrate, Cu(NO3)2 solution into FOUR
separate test tubes.
2. Placed a clean magnesium ribbon into each test tubes.
3. Steps 1 – 3 are repeated using clean zinc strip, iron nail, lead strip and copper strip
respectively to replace the magnesium ribbon. Use FRESH salt solution
4. All observations are recorded.
PROCEDURES
What observations are we expecting??
Observations are made after awhile to check if :
• there is any color change in the solution
• there is any solid deposits on the metal
• metal dissolves

16. DATA AND OBSERVATION
Salt
Solution
Magnesium
nitrate,
Mg(NO3)2
Zinc
nitrate,
Zn(NO3)2
Lead(III)
nitrate,
Pb(NO3)2
Copper(II)
nitrate
Cu(NO3)2Metal strip
Magnesium
Zinc
Lead
Copper

17. PKS 8
• OPERATIONAL DEFINITION :
DISPLACEMENT REACTION OCCURS WHEN THERE IS
DEPOSITION OF METALS WHEN DIFFERENT METALS ARE
DIPPED INTO A SALT SOLUTION.
HYPOTHESIS :
• THE GREATER THE NUMBER OF METALS THAT CAN
DISPLACE A METAL FROM THEIR SALT SOLUTION, THE
HIGHER ITS POSITION IN THE ELECTROCHEMICAL SERIES.