[knightsljx]

Hi all,

I need help with this phenomenon.

Both Fe3+  and Al3+ ions hydrolyse in water. Going by the charge density argument, aluminium has a smaller ionic radius and should distort the water molecules more, causing greater extent of hydrolysis. But empirical data suggests Fe3+ hydrolyses more. pKa of Fe3+ is about 2.2, pKa of Al3+ is about 5.0.

What other factors do I need to consider when discussing the hydrolysis of high charge density metal ions? Does ligand field stabilisation energy come into play?

Or is the data misinterpreted?

Thank you