Ions in solution hydrolysis

Like stability constants and other thermodynamic properties of metal ions in solution, hydrolysis constants are affected by ionic strength and temperature, and these should be specified when quoting precise pfta values. For the ballpark figures cited here, 25 °C and high dilution are assumed. 

This technique is similar in concept to fractional crystallization and has generally been effected by addition of hydroxide ion, or by the generation of this ion in solution. Hydrolysis occurs less extensively with La than with the other lanthanons and, due to the greater sdlubility product of La(OH)3 compared to those of the smaller tervalent rare earth cation hydroxides (ca. 10 for La(OH)3 compared to 10" for Lu(OH)3), it is feasible to precipitate the bulk of the other rare earths in the presence of ammonium ion and leave La, for the most part, behind. 

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