Key Definitions
- Bronsted-Lowry acid — a proton (H⁺) donor
- Bronsted-Lowry base — a proton (H⁺) acceptor
- Conjugate pair — an acid and its conjugate base differ by one proton
- Amphoteric / Amphiprotic — a substance that can act as both acid and base (e.g. water, amino acids)
Proton Transfer: HCl + H₂O
Think About It
Can NH₃ act as both an acid and a base? If so, give examples.
Yes — NH₃ is amphiprotic. As a base: NH₃ + HCl → NH₄⁺ + Cl⁻ (accepts H⁺). As an acid: NH₃ + Na → NaNH₂ + ½H₂ (donates H⁺ to form NH₂⁻). However, NH₃ is a much better base than acid.