Explain, with balanced ionic equations, why (a) \(\mathrm{CuI}_{2}\) dissolves in ammonia solution, (b) AgBr dissolves in \(\mathrm{NaCN}\) solution, (c) \(\mathrm{HgCl}_{2}\) dissolves in KCl solution.

Short Answer

Expert verified
The balanced ionic equations for the dissolution are as follows: (a) \(\mathrm{CuI}_2 + 4NH_3 ⟶ \mathrm{[Cu(NH_3)_4]}^{2+} + 2I^−\)(b) \(\mathrm{AgBr} + 2CN^- ⟶ \mathrm{[Ag(CN)_2]}^− + Br^-\)(c) \(\mathrm{HgCl}_{2} + Cl^- ⟶ \mathrm{HgCl}_{3}^-\)

Step by step solution

01

Dissolution of \(\mathrm{CuI}_2\) in ammonia solution

The first reaction involves the complex formation of Copper(II) ion with four molecules of Ammonia. It can be expressed in a reaction as follows: \[\mathrm{CuI}_2 + 4NH_3 ⟶ \mathrm{[Cu(NH_3)_4]}^{2+} + 2I^−\]where \(\mathrm{CuI}_2\) breaks down into Copper(II) ions and iodide ions. These Copper(II) ions then react with ammonia molecules to form a complex ion.
02

Dissolution of AgBr in \(\mathrm{NaCN}\) solution

In the second part of the exercise, AgBr reacts with \(\mathrm{NaCN}\) to form soluble complex ion. The actual ionic equation is:\[\mathrm{AgBr} + 2CN^- ⟶ \mathrm{[Ag(CN)_2]}^− + Br^-\]The \(\mathrm{NaCN}\) breaks up into sodium ions and cyanide ions. The cyanide ions then react with the silver ion part of the silver bromide to form a soluble complex ion.
03

Dissolution of \(\mathrm{HgCl}_{2}\) in KCl solution

In the final sub-problem, \(\mathrm{HgCl}_{2}\) reacts with KCl and forms a soluble ionic complex. This reaction is represented by the following ionic equation:\[\mathrm{HgCl}_{2} + Cl^- ⟶ \mathrm{HgCl}_{3}^-\]The \(\mathrm{KCl}\) breaks up into potassium ions and chloride ions. The chloride ions then react with the mercuric ions to form a soluble complex ion.

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