Mg^(2+) ions is essential for selective precipitation of Fe(OH)_(3) be

1.	Mg^(2+) ions is essential for selective precipitation of Fe(OH)_(3) be aqueous NH_(3).
Answer» Solution :Aqueous `NH_(3)` means `NH_(3) + H_(2)O rarr NH_(4)OH` `Fe^(3+) + 3OH^(THETA)` (from `NH_(4)OH) rarr Fe(OH)_(3)` `NH_(4)OH rarr NH_(4)^(o+) + overset(Theta)OH` Due to common ion `(NH_(4))`, the supression of ionisation of `NH_(4)OH` TAKES PLACE, so the concentartion, of `overset(Theta)OH` is less. So only the `Fe(OH)_(3)` ppt. not `Mg(OH)_(2)` since `K_(sp)` of `Fe(OH)_(3) lt K_(sp) "of" Mg(OH)_(2)`

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