Why do the amphoteric hydroxides form on addition of a little NaOH(aq), but dissolve in excess, to give a solution?
Cr3+ forms green-blue ppt, then a green solution. Al3+ forms a white ppt, then a colourless solution. Zn2+ forms a white ppt, then a colourless solution.
Why do the amphoteric hydroxides form on addition of a little NaOH(aq), but dissolve in excess, to give a solution?
Cr3+ forms green-blue ppt, then a green solution. Al3+ forms a white ppt, then a colourless solution. Zn2+ forms a white ppt, then a colourless solution.
Any information would be greatly appreciated.
The high charge density of the ion helps polarise the water molecule ligands.