⚛️ Redox Reactions — Oxidation, Reduction & Electrochemistry
Redox reactions are more than just electron transfers—they power batteries, biology, and DAT questions.
Expect problems involving oxidation numbers, reaction balancing, and cell diagram interpretation.
This guide will help you simplify the redox rules and crush electrochemistry questions with confidence.
🔋 What Are Redox Reactions?
Redox = Reduction + Oxidation
Oxidation: Loss of electrons
Reduction: Gain of electrons
📌 DAT Memory Trick: OIL RIG (Oxidation Is Loss, Reduction Is Gain)
🧮 Assigning Oxidation Numbers
Rule | Example |
---|---|
Element alone = 0 | O₂, Fe, Cl₂ |
Group 1/2 metals = +1 / +2 | Na⁺, Ca²⁺ |
Oxygen = –2 (peroxides = –1) | H₂O (–2), H₂O₂ (–1) |
Hydrogen = +1 (–1 w/ metals) | HCl (+1), LiH (–1) |
Halogens = –1 (except w/ O) | NaCl (–1), ClO₄⁻ |
⚖️ How to Balance Redox Reactions (Acidic Solution)
Balance all elements except O and H
Balance O using H₂O
Balance H using H⁺
Balance charges with e⁻
Combine half-reactions and cancel species
✅ For basic solutions, add OH⁻ to both sides to neutralize extra H⁺.
⚡ Galvanic vs. Electrolytic Cells
Feature | Galvanic Cell | Electrolytic Cell |
---|---|---|
Spontaneous? | Yes (ΔG < 0) | No (ΔG > 0) |
Energy Source | Generates current | Requires external power |
Anode | Oxidation (–) | Oxidation (+) |
Cathode | Reduction (+) | Reduction (–) |
Electron Flow | Anode → Cathode | Anode → Cathode |
Example | Batteries | Electroplating |
📌 DAT Tip: AnOx & RedCat = Anode Oxidation, Cathode Reduction
🧠 Redox DAT Question Types
“Assign oxidation numbers to each atom”
“Balance this redox reaction in acid/base”
“Which species is reduced?”
“What’s the function of the salt bridge?”
“What is the direction of electron flow?”
🎯 Call to Action
Struggling to remember redox logic?
King of the Curve gives you:
Redox diagrams + animation tools
Reaction balancing practice
Interactive electrochemistry questions
DAT-style drills & multiplayer study
✅ Summary
Redox = oxidation + reduction; track electrons
Assign oxidation numbers based on key rules
Use half-reactions to balance redox in acidic/basic media
Understand how electrochemical cells function and label components
Frequently Asked Questions (FAQs)
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