Topic 1 · 9.1 · Free
Topic Notes · Easy summaries with diagrams
Chapter 9 — chapter 9
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Topic 1 of 8
📘Easy summary
Arrhenius: an acid gives H⁺ and a base gives OH⁻ in water. Brønsted-Lowry: an acid is a proton (H⁺) donor and a base is a proton acceptor. An acid–base reaction is a proton transfer. When an acid loses a proton it forms its conjugate base; when a base gains a proton it forms its conjugate acid. Conjugate pairs differ by one H⁺: HCl/Cl⁻, NH₄⁺/NH₃, H₃O⁺/H₂O, H₂O/OH⁻. In NH₃ + H₂O ⇌ NH₄⁺ + OH⁻, NH₃ is the base and H₂O is the acid. Water is amphoteric: base with HCl, acid with NH₃. The stronger the acid, the weaker its conjugate base.
⭐Key points
- Acid = proton donor; base = acceptor.
- Conjugate pair differs by H⁺.
- Strong acid ↔ weak conjugate base.
🔬Diagram
🌿Real-life example
HF + H₂O ⇌ F⁻ + H₃O⁺: pairs HF/F⁻ and H₃O⁺/H₂O.
💡Exam tip
- Always label both conjugate pairs.
✅Quick check
1. Conjugate base of water:
2. In NH₃ + H₂O ⇌ NH₄⁺ + OH⁻, water is:
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