Displacement Reactions - Halogens
Chemistry: AQA GCSE Higher, topic 4.2.3
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
- Sodium bromide + chlorine → sodium chloride + bromine
- 2NaBr + Cl2 → 2NaCl + Br2
Bromide ions (Br-)
- Bromide ions are oxidised (electrons are lost):
- 2Br- → Br2 +2e-
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Chlorine (Cl2)
- Chlorine is reduced (electrons are gained):
- Cl2 + 2e- → 2Cl-
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?
The equation 2NaBr + Cl2 → 2NaCl + Br2 shows chlorine displacing bromine from sodium bromide. What does this show about the reactivity of chlorine compared with bromine?