If $F e^{3 +}$ and $C r^{3 +}$ both are present group III of qualitative analysis, then distinction can be made by

see full answer

Your Exam Success, Personally Taken Care Of

1:1 expert mentors customize learning to your strength and weaknesses – so you score higher in school , IIT JEE and NEET entrance exams.

An Intiative by Sri Chaitanya

addition of $N H_{4} O H$ in the presence of $N H_{4} C I$ when only $F e {(O H)}_{3}$ is precipitated

Both(b) and (c)

Addition of $N H_{4} O H$ in the presence of $N H_{4} O H$ when $C r {(O H)}_{3}$ and $F e {(O H)}_{3}$ both are precipitated and on adding $B r_{2}$ water and $N a O H, C r {(O H)}_{3}$ dissolves

Precipitate of $C r {(O H)}_{3}$ and $F e {(O H)}_{3}$ as obtained in (b) are treated with conc. HCI when only $F e {(O H)}_{3}$ dissolves

answer is D.

(Unlock A.I Detailed Solution for FREE)

Best Courses for You

JEE

NEET

Foundation JEE

Foundation NEET

CBSE

Detailed Solution

If $F e^{3 +}$ and $C r^{3 +}$ both are present then very first solid ammonium chloride and ammonium hydroxide is added slowly till the solution gives smell of ammonia. $F e^{3 +}$ and $C r^{3 +}$ precipitates in the hydroxide form. For identification, precipitate is treated with NaOH and $B r_{2}$ water, yellow colouration confirms $C r^{3 +}$ ion.
$\begin{array}{l} 2 N a O H + B r_{2} \to N a B r O + N a B r + H_{2} O \\ N a B r O \to N a B r + [O] \\ 2 C r {(O H)}_{3} + 4 N a O H + 3 [O] \to 2 N a_{2} C r O_{4} + 5 H_{2} O \end{array}$
Solution is acidified and treated with lead acetate solution.
$N a_{2} C r O_{4} + P b {(C H_{3} C O O)}_{2} \to \underset{Y e l l o w p p t}{P b C r O_{4} ↓} + 2 C H_{3} C O \bar{O} \overset{+}{N} a$