Two coloured salt solutions of two metals $A$ and $B$ gave precipitates with $N a O H$ and ${N H}_{4} O H$ . The oxidation states of salts metal $A$ and $B$ are same. On further addition of ${N H}_{4} O H$ , the precipitate disappears, in the case of $B$ . There is no such change in the case of ' $A$ ' either with $N a O H$ or ${N H}_{4} O H$ . Identify $A$ and $B$ . Give necessary equations :

{F e}^{+ 2}, {C u}^{+ 2}

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{C u}^{+ 2}, {F e}^{+ 2}

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{F e}^{+}, {F e}^{+ 3}

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{F e}^{+ 3}, {C u}^{+ 2}

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Solution

The correct option is A ${F e}^{+ 2}, {C u}^{+ 2}$
Both $F e^{2 +}$ and $F e^{3 +}$ gives precipitate of their hydroxides $(F e (O H)_{2})$ and $(F e (O H)_{3})$ with $N H_{4} O H$ or $N a O H$ .
When $N H_{4} O H$ or $N a O H$ is added to a solution of copper ions the copper ions will react with the few $O H^{-}$ to make insoluble $C u (O H)_{2}$ . The solid exists in a suspension. As more $N H_{4} O H$ is added the insoluble $C u (O H)_{2}$ will dissolve as ${[C u (N H_{3})_{4}]}^{2 +}$ is formed. The copper-ammonia complex ion is a deep purple, and it will be difficult to see through the solution, but there won't be any solid precipitate remaining.
As the oxidation state of both salts is similar thus the salts contain $F e^{2 +}$ and $C u 2 +$ ions respectively.

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Similar questions

{C u}^{2 +}

ions react with

{F e}^{2 +}

ions according to the following reaction:

{C u}^{2 +} + 2 {F e}^{2 +} ⇌ C u + 2 {F e}^{3 +}

At equilibrium, the concentration of

{C u}^{2 +}

ions is not changed by the addition of:

Q. (a) Define atomicity with an example.

(b) Write the historical name and systematic name of the following ions :

C u^{+}, C u^{+ 2}, F e^{+ 2}, F e^{+ 3}

Q. Compare the ionic size of:
(a)

{F e}^{2 +} a n d {F e}^{3 +}

(b)

{C u}^{3 +} a n d {C u}^{2 +}

(c)

H^{+}, H^{-} a n d H

$F e C l_{3}$ reacts with ammonium hydroxide to give a reddish brown precipitate of metallic hydroxide which is insoluble in excess of $N H_{4} O H$ . Name this precipitate.

$F e S O_{4}$ reacts with ammonium hydroxide to give dirty green precipitate of metallic hydroxide which is insoluble in excess of $N H_{4} O H$ . Name this precipitate.

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