The complete lecture — acids & bases come alive in the live panel as you read. Scroll down; the animation keeps pace, and you can run a titration yourself.
1 — Properties of acids & bases
Acids taste sour and turn litmus red; bases feel soapy and turn litmus blue. In water, acids give H⁺ and bases give OH⁻.
2 — Theories of acids & bases
| Theory | Acid | Base |
|---|
| Arrhenius | gives H⁺ | gives OH⁻ |
| Brønsted | H⁺ donor | H⁺ acceptor |
| Lewis | e⁻-pair acceptor | e⁻-pair donor |
3 — Conjugate acid–base pairs
HCl + H₂O ⇌ H₃O⁺ + Cl⁻HCl/Cl⁻ and H₂O/H₃O⁺ are the conjugate pairs
4 — Strong vs weak acids & bases
- Strong — fully ionised (HCl, NaOH). Weak — partly (CH₃COOH, NH₃).
5 — Ionic product of water (Kw)
at 25 °CKw = [H⁺][OH⁻] = 1×10⁻¹⁴ · pure water [H⁺]=[OH⁻]=10⁻⁷
6 — The pH & pOH scale
DefinitionspH = −log[H⁺] · pH + pOH = 14
7 — Ka, Kb and pKa
HA ⇌ H⁺ + A⁻Ka = [H⁺][A⁻]/[HA] · pKa = −log Ka · Ka×Kb = Kw
8 — Neutralisation & salts
ExampleHCl + NaOH → NaCl + H₂O
9 — Salt hydrolysis
| Salt | Solution |
|---|
| NaCl (SA+SB) | neutral |
| NH₄Cl (SA+WB) | acidic |
| CH₃COONa (WA+SB) | basic |
10 — Buffer solutions
Henderson–HasselbalchpH = pKa + log([salt]/[acid])
Blood is buffered near pH 7.4.
11 — Indicators & titration
25 cm³ of 0.1 M HCl is titrated with 0.1 M NaOH. Move the slider in the live panel to add base; the pH curve and the beaker colour respond, with a sharp jump at the equivalence point (25 cm³).
12 — Exam recap
- Properties & the three theories.
- Conjugate pairs; strong vs weak.
- Kw; pH = −log[H⁺]; pH + pOH = 14.
- Ka, Kb, pKa.
- Neutralisation, salts, hydrolysis, buffers.
- Indicators & titration calculations.