Acids
- An acid is a chemical substance which ionises in water to produce hydrogen ions, H+ / hydroxonium ions, H3O+.
- H+(aq) + H2O(l) –> H3O+(aq)
- Example: HCl(g) + H2O(l) –> H3O+(aq) + Cl -(aq)
| Acid | Acid name | Ions |
| HCl | Hydrochloric acid | H+, Cl - |
| HNO3 | Nitric acid | H+, NO3- |
| H2SO4 | Sulphuric acid | H+, SO42- |
| CH3COOH | Ethanoic acid | H+, CH3COO - |
- Monoprotic acid = acid can produce only one hydrogen ion per molecule in water. (Example: HCl)
- Diprotic acid = acid can produce two hydrogen ions per molecule in water. (Example: H2SO4)
- Triprotic acid = acid can produce three hydrogen ions per molecule in water. (Example: H3PO4)
Sodium hydroxide
- A base is a chemical substance which reacts with an acid to produce a salt and water only.
- Base(s) + acid(aq) –> salt + water (l).
- Example: NaOH(s) + HCl(aq) –> NaCl(aq) + H2O(l)
| Base | Formula | Solubility in water | Ions in the aqueous solution |
| Copper(II) oxide | CuO | Insoluble base | - |
| Lead(II) oxide | PbO | Insoluble base | - |
| Magnesium oxide | MgO | Insoluble base | - |
| Zinc hydroxide | Zn(OH)2 | Insoluble base | - |
| Aluminium hydroxide | Al(OH)3 | Insoluble base | - |
| Sodium oxide | Na2O | Soluble base (alkali) | Na+, O2- |
| Calcium oxide | CaO | Soluble base (alkali) | Ca2+, O2- |
| Sodium hydroxide | NaOH | Soluble base (alkali) | Na+, OH- |
| Potassium hydroxide | KOH | Soluble base (alkali) | K+, OH- |
| Barium hydroxide | Ba(OH)2 | Soluble base (alkali) | Ba2+, OH- |
