Displacement Reactions - Halogens

Science: KS3, topic 2.6.10

Displacement Reactions - Halogens

More reactive substances can displace (replace) less reactive substances from compounds. For example, chlorine can displace bromine from a compound:

Displacement reaction

Displacement reaction

  • Sodium bromide + chlorine → sodium chloride + bromine
  • 2NaBr + Cl2 → 2NaCl + Br2
Bromide ions (Br-)

Bromide ions (Br-)

  • Bromide ions are oxidised (electrons are lost):
  • 2Br- → Br2 +2e-
Chlorine (Cl2)

Chlorine (Cl2)

  • Chlorine is reduced (electrons are gained):
  • Cl2 + 2e- → 2Cl-
Spectator ions

Spectator ions

  • The sodium ions are unchanged in the reaction, so we call them spectator ions.

Test yourself on Displacement Reactions - Halogens

  • More reactive substances can displace less reactive substances from compounds. Chlorine can displace bromine from sodium bromide. What does this show about the reactivity of chlorine compared with bromine?

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