Oxidising Power and Displacement

Oxidising order: F₂ > Cl₂ > Br₂ > I₂ Displacement: Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂ Cl₂ + 2I⁻ → 2Cl⁻ + I₂ Br₂ + 2I⁻ → 2Br⁻ + I₂ I₂ + Cl⁻ / Br⁻ → no displacement Halogen X₂ oxidises; halide X⁻ is the reduced form.

Stronger halogen pushes out weaker halide from solution. Order of strength: F₂ > Cl₂ > Br₂ > I₂. Cl₂ can free Br₂ or I₂; Br₂ can free I₂; I₂ cannot free Cl₂ or Br₂.

Write ionic equations and predict colour: Br₂ orange/red-brown; I₂ brown (aq) or violet (organic). Remember I₂ does not displace Cl⁻/Br⁻. Separate oxidising power (X₂) from reducing power of halides (I⁻ strongest reductant of Cl⁻/Br⁻/I⁻).

Down the group, larger atoms hold the gained electron less tightly (lower electronegativity / less favourable electron gain in the school story), so oxidising power falls. Conversely, I⁻ is the strongest reductant of the common triad. Fluorine’s extreme oxidising power is a named trend extreme, not a student bench reagent.

F₂>Cl₂>Br₂>I₂ oxidising · Cl₂ displaces Br⁻/I⁻ · Br₂ displaces I⁻ · I₂ does NOT displace Cl⁻/Br⁻ · X₂ ≠ X⁻.