1. Tardigrade
  2. Question
  3. Chemistry
  4. The only cations present in a slightly acidic solution are Fe3+,Zn2+ and Cu2+ . The reagent that when added in excess to this solution would identify and separate Fe3+ in one step is

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. The only cations present in a slightly acidic solution are $ F{{e}^{3+}},Z{{n}^{2+}} $ and $ C{{u}^{2+}} $ . The reagent that when added in excess to this solution would identify and separate $ F{{e}^{3+}} $ in one step is

ManipalManipal 2008

Solution:

$Fe ^{3+}, Zn ^{2+}$ and $Cu ^{2+}$ ions are present in slightly acidic solution. On adding $6 M \,NH _{3}$ solution, i.e., $6 M\, NH _{4} OH$ we get the following reactions
$Fe ^{3+}+3 OH ^{-} \longrightarrow \underset{\text{dark brown ppt.}}{Fe ( OH )_{3}}$
$Zn ^{2+}+4 NH _{3} \longrightarrow \underset{\text{colourless solution}}{[Zn(NH_3)_4]^{2+}}$
$Cu^{2+} + 4NH_3 \to \underset{\text{deep blue solution}}{[Cu(NH_3)_4]^{2+}}$
In this way, dark brown ppt. of $Fe ( OH )_{3}$ can be separated from $Cu ^{2+}$ and $Zn ^{2+}$ amine complex solutions in a single step by adding $6 M NH _{3}$.