Q8(c). Principles of four methods of separating the lanthanides
Briefly explain the principles involved in the following methods of separation of the lanthanides: (i) repeated fractional crystallisation (ii) solvent extraction (iii) fractional precipitation (iv) change of oxidation state.
Answer in brief
The first three methods use the small, regular fall in Ln³⁺ size from La to Lu, which changes solubility, basic strength and complex stability a little at every step; the fourth takes an ion to +4 or +2, giving it quite different properties.
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Coversseparation of lanthanidessolvent extractionfractional crystallisationfractional precipitationion exchangelanthanide contraction
All parts of Question 8
- 8(a) Why all F atoms of PF₅ look alike in the ¹⁹F NMR spectrum10 marks
- 8(b)(i) Possible arrangements and shape of ClF₃10 marks
- 8(b)(ii) Structure and bonding of B₂H₆10 marks
- 8(c) Principles of four methods of separating the lanthanides20 marks