9.2.5—Reactions of the chlorides NaCl, MgCl2, Al
- Syllabus
- 9701–2028–2029
- Objective
- 9.2.5
- Level
- AS
Period 3 chlorides hydrolyse differently because their bonding changes
Period 3 chlorides range from ionic lattices to covalent molecules. Their reaction with water and the pH of the resulting solution depend on the chloride’s bonding and the polarising power of the central atom.
Ionic chlorides often dissolve to give neutral ions, while covalent chlorides hydrolyse to form acidic solutions and hydrogen chloride.
NaCl dissolves without hydrolysis, whereas PCl₃ reacts with water to form H₃PO₃ and HCl. Aluminium chloride shows strong polarisation and acidic aqueous behaviour.
Do not assume every chloride gives a neutral solution. Ask whether the chloride is ionic or covalent and whether hydrolysis occurs.
ConceptA-Level CAIE Chemistry AS