Chapter summary
Acid-Base Chemistry, at a glance
Use ions and reaction patterns to explain acids, bases and salts.
O-Level 5086 / 5088 (2026) / SEC G3 K326 / K328 (2027)
Quick revision
Revisit the essentials, then return to an explanation when you need it.
| Term | Definition to write |
|---|---|
| Acid | A substance that produces hydrogen ions, H+(aq), when dissolved in water. |
| Alkali | A soluble base that produces hydroxide ions, OH-(aq), when dissolved in water. |
| Base | A substance that reacts with an acid to form a salt and water only. Most bases are metal oxides or hydroxides. |
| Neutralisation | The reaction between hydrogen ions and hydroxide ions to form water: H+(aq) + OH-(aq) → H2O(l). |
| Salt | The compound formed when the hydrogen ions of an acid are replaced by metal ions or ammonium ions. |
Acids supply H+; alkalis supply OH-. Acid + base gives salt and water; carbonate also gives CO2; suitable metal gives H2. Alkali and ammonium salt release NH3 on warming.
Quick recall
Which ion do all acids produce in water, and which ion do all alkalis produce?