This document provides an overview of electrochemistry and electrochemical cells. It defines key terms like oxidation, reduction, anode, and cathode. Oxidation occurs at the anode and involves losing electrons, while reduction occurs at the cathode and involves gaining electrons. Electrochemical cells convert chemical energy to electrical energy through redox reactions. A simple cell consists of two electrodes connected by a wire submerged in an electrolyte. Several examples of simple cells are described using zinc, iron or copper electrodes reacting with hydrogen ions in solution.

1. Electrochemistry – I
Electrochemical Cells
For
GCE(O/L)
&
IGCSE
students

2. • Reduction - Gaining electrons
• Oxidation - Losing electrons
Mnenomic- “OIL RIG”
»Oxidation is Losing
»Reduction is Gaining
• The reactions in which oxidation occurs with
reduction are REDOX REACTIONS.
Redox Reactions

3. Need to know
• Electrode
a conductor through
which electricity enters
or leaves an object,
substance, or region.

4. Electrodes
• Anode - Electrode at which the
oxidation half reaction occurs
• Cathode - Electrode at which the
oxidation half reaction occurs

5. •Electrolyte - a substance that produces
an electrically conducting
solution when dissolved in
a polar solvent; water

6. Electrochemical cells
• Converts chemical energy
into electrical energy
• In a simple cell
– Two electrodes connected
by a wire
– An acidified solution as the
electrolyte
• Current passes from
cathode to anode
(from positive terminal to
negative terminal)

7. Electrodes of a Simple Cell
Anode
• One electrode is the
anode
• More reactive metal
becomes the anode
• Oxidation half reaction
occurs at anode
• Negative terminal
Cathode
• Other electrode is the
cathode
• Less reactive metal
becomes the cathode
• Reduction half reaction
occurs at cathode
• Positive terminal

8. A Simple Electrochemical Cell

9. Activity- 1
Materials
required
• A small beaker
• Diluted sulphuric acid
• A zinc metal strip
Method
• Add the diluted sulphuric solution to the
beaker
• Dip a part of the zinc strip into the solution

10. Continued..
Observations
•Zn strip dissolve
•Gas bubbles are liberated at the Zn strip

11. Continued..
H+ takes electrons and hydrogen gas is liberated
2H+ + 2e H2(g)
Sulphuric acid dissociates
H2SO4 2H+ + SO4
2-
Zn metal dissolves as electrons are leaving from the Zn atoms
Zn(s) Zn2+
(aq) + 2e

12. • Oxidation half reaction
• Zn(s) Zn2+
(aq) + 2e
• Reduction half reaction
• 2H+ + 2e H2(g)
• Balanced ionic equation
• Zn(s) + 2H+ Zn2+
(aq) + H2(g)
• Completed balanced reaction
• Zn(s) + H2SO4(aq) ZnSO4(aq) + H2(g)

13. Activity - 2
• Observations
•Zn strip dissolve
•Gas bubbles are liberated at the Cu strip

14. Cont.
• Conclusions
Zn(s) Zn2+
(aq) + 2e oxidation
2H+ + 2e H2(g) reduction
• Balanced ionic equation
Zn(s) + 2H+ Zn2+
(aq) + H2(g)
Oxidation
At anode
Zn
Negative
terminal
Reduction
At cathode
Cu
Positive
terminal

15. Activity - 3
• Observations
•Iron strip dissolve
•Gas bubbles are liberated at the Cu strip
uFe
Cu

16. Cont.
• Conclusions
Fe(s) Fe2+
(aq) + 2e oxidation
2H+ + 2e H2(g) reduction
• Balanced ionic equation
Fe(s) + 2H+ Fe2+
(aq) + H2(g)
Oxidation
At anode
Fe
Negative
terminal
Reduction
At cathode
Cu
Positive
terminal

17. Activity - 4
• Observations
•Zn strip dissolve
•Gas bubbles are liberated at the Cu strip

18. Cont.
• Conclusions
Zn(s) Zn2+
(aq) + 2e oxidation
2H+ + 2e H2(g) reduction
• Balanced ionic equation
Zn(s) + 2H+ Zn2+
(aq) + H2(g)
Oxidation
At anode
Zn
Negative
terminal
Reduction
At cathode
Fe
Positive
terminal

19. Thank You!