Question

Al(OH)3 is soluble in NaOH(aq) whereas Fe(OH)3 is insoluble.Why? ​

Answer 1

Fe(OH)

3

is insoluble in aqueous sodium hydroxide solution. Whereas Al(OH)

3

is soluble in excess of sodium hydroxide. Thus, to separate Fe(OH)

3

and Al(OH)

3

, aqueous NaOH solution is added. Al(OH)

3

will dissolve in it whereas Fe(OH)

3

will remain insoluble. The two can then be separated by filtration.