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Oxidising Power and Displacement — Displacement
Displacement is the practical redox test of halogen oxidising power: a more reactive halogen X₂ oxidises the halide of a less reactive halogen. Cl₂ displaces Br⁻ and I⁻; Br₂ displaces I⁻; I₂ does not displace Cl⁻ or Br⁻.
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Oxidising Power and Displacement — Displacement
What is it?
Displacement is the practical redox test of halogen oxidising power: a more reactive halogen X₂ oxidises the halide of a less reactive halogen. Cl₂ displaces Br⁻ and I⁻; Br₂ displaces I⁻; I₂ does not displace Cl⁻ or Br⁻.
In simple words
- Cl₂ displaces Br⁻ and I⁻; Br₂ displaces I⁻; I₂ displaces neither Cl⁻ nor Br⁻.
- Ionic equations + colours.
- Subtopic of oxidising power and displacement.
What you should learn
- Explain Oxidising Power and Displacement — Displacement using Group 17 language.
- Link trends to size, shielding, forces and bond strength.
- Apply equations and observations in FBISE-style answers.
Recommended for Class 11
Full school-level explanation
Displacement is the practical redox test of halogen oxidising power: a more reactive halogen X₂ oxidises the halide of a less reactive halogen. Cl₂ displaces Br⁻ and I⁻; Br₂ displaces I⁻; I₂ does not displace Cl⁻ or Br⁻.
Beginner
Stronger halogen pushes out weaker halide. Cl₂ can make Br₂ or I₂ appear; Br₂ can make I₂ appear; I₂ cannot make Cl₂ or Br₂.
Intermediate
Memorise the three working equations and the no-reaction case. Attach colours to products.
Advanced
Displacement is a competition for electrons between X₂X⁻ couples. The higher couple oxidises the lower halide.
Remember
Cl₂→Br⁻,I⁻ · Br₂→I⁻ · I₂↛Cl⁻,Br⁻ · equations + colours · parent oxidising topic.
Deeper understanding
Go deeper on Oxidising Power and Displacement — Displacement: connect the definition to reasons, relationships, exceptions, and exam wording.
Common mistakes
Exam focus
Works
Fails
Colours
Parent
Exam focus
Quick revision
- Beginner: Stronger halogen pushes out weaker halide. Cl₂ can make Br₂ or I₂ appear; Br₂ can make I₂ appear; I
- Intermediate: Memorise the three working equations and the no-reaction case. Attach colours to products.
- Cl₂ displaces Br⁻ and I⁻; Br₂ displaces I⁻; I₂ displaces neither Cl⁻ nor Br⁻.
- Ionic equations + colours.
- Subtopic of oxidising power and displacement.
For long answers on Oxidising Power and Displacement — Displacement: define clearly → explain the main parts → give one example → state one exam caution.
Exam Focus
Exam Focus
Important points
- Beginner: Stronger halogen pushes out weaker halide. Cl₂ can make Br₂ or I₂ appear; Br₂ can make I₂ appear; I
- Intermediate: Memorise the three working equations and the no-reaction case. Attach colours to products.
- Cl₂ displaces Br⁻ and I⁻; Br₂ displaces I⁻; I₂ displaces neither Cl⁻ nor Br⁻.
- Ionic equations + colours.
Common exam traps
- Predicting I₂ displaces Cl⁻.
- Forgetting ionic equations.
Long question structure
Definition → key parts → example → exam caution
Common Mistakes
Common Mistakes
- Mistake
Predicting I₂ displaces Cl⁻.
- Mistake
Forgetting ionic equations.
- Mistake
Missing colour observations.
Revision Zone
60-Second Revision
Quick cues from this topic — use them for last-minute revision.
Beginner: Stronger halogen pushes out weaker halide. Cl₂ can make Br₂ or I₂ appear; Br₂ can make I₂ appear; I
Intermediate: Memorise the three working equations and the no-reaction case. Attach colours to products.
Cl₂ displaces Br⁻ and I⁻; Br₂ displaces I⁻; I₂ displaces neither Cl⁻ nor Br⁻.
Ionic equations + colours.
Displacement is the practical redox test of halogen oxidising power: a more reactive halogen X₂ oxidises the halide of a less reactive halogen. Cl₂ displaces Br
- Definition
- Displacement is the practical redox test of halogen oxidising power: a more reactive halogen X₂ oxidises the halide of a less reactive halogen. Cl₂ displaces Br
- Critical warning
- Predicting I₂ displaces Cl⁻.
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Exam Practice
Define
Q1. Define Oxidising Power and Displacement — Displacement.
Explain
Q2. Explain: Beginner.
Example
Q3. Give one clear example of Oxidising Power and Displacement — Displacement and say why it fits.
Mistake
Q4. State one common mistake students make about Oxidising Power and Displacement — Displacement.
Exam note
Q5. Write a short exam note on Oxidising Power and Displacement — Displacement: definition, two points, one example.
Sources & References
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.