Redox Reaction Concepts Tutorial
- Reactions in which electrons are transferred from one species to another are known as
⚛ redox reactions
⚛ electron-transfer reactions
- A redox reaction is made up of two half-reactions:
(i) A reduction reaction in which one species gains electrons:
X + e- → X-
(ii) An oxidation reaction in which one species loses electrons:
M → M+ + e-
Electrons, e-, are being transferred from the species that undergoes oxidation, M, to the species that undergoes reduction, X:
X + M → X- + M+
- The species that undergoes reduction is known as the oxidant or oxidizing agent because it causes another species to be oxidized:
- The species that undergoes oxidation is known as the reductant or reducing agent because it causes another species to be reduced:
- In a redox reaction:
(i) The oxidation state (oxidation number) of the species which gains electrons decreases.
The oxidation state (oxidation number) of the oxidizing agent (oxidant) decreases.
(ii) The oxidation state (oxidation number) of the species which loses electrons increases.
The oxidation number (oxidation state) of the reducing agent (reductant) increases.
X is the oxidant
M is the reductant
redox reaction X + M → X- + M+ oxidation number
0 0 -1 +1
Oxidation number of the oxidant (oxidizing agent), X, has decreased from 0 to -1
Oxidation number of the reductant (reducing agent), M, has increased from 0 to +1
- There are many uses for redox reactions:
⚛ Recharging rechargable batteries
⚛ Electrorefining of metals (copper refinement)
⚛ Electroplating (also known as electrodeposition)
⚛ Quantitative analysis (redox titrations)