Redox Reactions: High School Level

1. REDOX
REACTIONS

2. Objectives
Define oxidation, reduction, oxidizing
agent, reducing agent, and oxidation
numbers.
Examples of redox reactions.
Redox reactions in everyday lives.

3. Oxidation
• A chemical reaction in which the atoms or
ions of an element experience an increase
in its oxidation state.
• It can also be described as a process
whereby a molecule/element/ion loses an
electron or electrons during a chemical
reaction.
e.g. Na → Na+ + e-

4. Reduction
• A chemical reaction in which the atoms or
ions of an element experience a decrease
in its oxidation state.
• It can also be described as a process
whereby a molecule/element/ion gains an
electron or electrons during a chemical
reaction.
e.g. Cl + e- → Cl-

5. Reduction-Oxidation
Reactions
• The oxidation and reduction processes always occur
simultaneously.
• Reduction-oxidation reactions are shortened to ‘redox reactions’.
• The electrons lost by one substance are gained by another
substance.
e.g. The reaction of Na and Cl to produce NaCl is a redox
reaction.
Cl + e- → Cl- + Na → Na+ + e-
=> 2Na + Cl2 → 2NaCl

6. Oxidizing and Reducing agents
Oxidizing agent
• A substance that is reduced(undergoes reduction) during a redox
reaction.
• In the NaCl redox reaction, Cl- is the reducing agent.
Reducing agent
• A substance that is oxidized(undergoes oxidation) during a redox
reaction.
• In the NaCl redox reaction, Na+ is the oxidizing agent.

7. Oxidation Numbers
• Oxidation number is the charge which an atom possesses when
all other atoms are removed from it as ions. The charge may be
‘positive’ or ‘negative’.
• The oxidation number(state) of an element varies depending
on the nature of compound in which it is present.
e.g. Oxygen (O) in KMnO4 has a -2 oxidation number.

9. References
• Foltz, C. (2010). ‘Chapter 19.1: Oxidation and Reduction’ [PowerPoint presentation]. Available at:
https://www.slideshare.net/cfoltz/chapter-191-oxidation-and-reduction (Accessed: 19 August
2022).
• Dr. Srivastava, T. (2010). ‘Redox reaction’ [PowerPoint presentation]. Available at:
https://www.slideshare.net/tanujanautiyal/redox-reactions-59297821 (Accessed: 19 August
2022).
• Guillotine, N. (2013). ‘Redox reaction Group C’. [PowerPoint presentation]. Available at:
https://www.slideshare.net/NoxianGuillotine/redox-reaction-group-c (Accessed: 19 August 2022).
• Xinleho. (2013). ‘Redox reaction (GROUP E)’ [PowerPoint presentation]. Available at:
https://www.slideshare.net/xinleho/redox-reaction-group-e (Accessed: 19 August 2022).
• Gm point Blank. (2012). ‘Redox reaction’. [PowerPoint presentation]. Available at:
https://www.slideshare.net/nelsonproflay/redox-reaction-14262872 (Accessed: 19 August 2022).