Practice question · Sort into groups
In each reaction, identify the highlighted species’ role in Brønsted–Lowry terms.
Groups: Acid (proton donor) · Base (proton acceptor)
- NH₃ in: NH₃ + H₂O → NH₄⁺ + OH⁻
- H₂O in: HCl + H₂O → Cl⁻ + H₃O⁺
- H₂O in: NH₃ + H₂O → NH₄⁺ + OH⁻
- HCl in: HCl + H₂O → Cl⁻ + H₃O⁺
Hints
- Track the proton (): whoever loses one acted as acid, whoever gains one acted as base.
- Water appears in both reactions, playing opposite roles.
Show the answer
Acid (proton donor): HCl in: HCl + H₂O → Cl⁻ + H₃O⁺, H₂O in: NH₃ + H₂O → NH₄⁺ + OH⁻
Base (proton acceptor): NH₃ in: NH₃ + H₂O → NH₄⁺ + OH⁻, H₂O in: HCl + H₂O → Cl⁻ + H₃O⁺
Why
Acidity is a role, not an identity: water donates a proton to ammonia but accepts one from HCl. Such amphoteric behaviour is the heart of the Brønsted–Lowry view, every acid–base reaction is just a proton handoff.
Practise Acid-base language and solution thinking
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