Question

Which of the following mixtures of ions in solution can be separated by using an $N{H}_3$ solution?

• A. $H{g}_2^{2+}$ and $A{g}^{+}$
• B. $B{i}^{3+}$ and $C{u}^{2+}$
• C. $A{g}^{+}$ and $P{b}^{2+}$
• D. $C{u}^{2+}$ and $C{d}^{2+}$

Answer 1

Answer: (A), (B), (C)

The correct options are
A $H{g}_2^{2+}$ and $A{g}^{+}$
B $B{i}^{3+}$ and $C{u}^{2+}$
C $A{g}^{+}$ and $P{b}^{2+}$

(A) $H{g}_2^{+2}$ and $A{g}^{+}$ ions in solution can be separated by using an $N{H}_3$ solution.
$A{g}^{+}$ is soluble in ammonia forming a complex while $H{g}_2^{+2}$ forms a black ppt of Hg with ammonia.
$A{g}^{+}+2N{H}_3\to \left[Ag\right(N{H}_3{)}_2{]}^{+}$
(B) $B{i}^{3+}$ and $C{u}^{2+}$ ions in solution can be separated by using an $N{H}_3$ solution.
$B{i}^{3+}$ is insoluble in ammonia, while $C{u}^{2+}$ forms soluble complex.
$C{u}^{2+}+4N{H}_3\to \left[Cu\right(N{H}_3{)}_4{]}^{2+}$
(C) $A{g}^{+}$ and $P{b}^{2+}$ ions in solution can be separated by using an $N{H}_3$ solution.
$A{g}^{+}$ is soluble in ammonia forming a complex
(D) $C{u}^{2+}$ and $C{d}^{2+}$ ions can be separated by treatment with KCN, followed by passing $H_{2}S$. Cd is precipitated as sulphide.