Q. Show the solubility of double salts?

The solubility of double salts of lanthanides such as 2Ln (N0₃).3Mg (N0₃)₂.24H₂0 and Ln2 (S0₄)₃ . Na₂S0₄.xH₂0 increases from La to Lu. Thus, the lanthanides could be separated from each other of fractional crystallisation of these salts. As these processes need to be repeated several times, these are very tedious and not very proficient. Though, the individual elements can now be separated with much less difficulty on a large scale by employing more efficient techniques of solvent extraction and ion exchange chromatography.