Question

\[AgCl\] is soluble in \[N{H_4}OH\] solution. The solubility is due to the formation of?
A. \[AgOH\]
B. \[\;A{g_2}O\]
C. \[\;{\left[ {Ag{{\left( {N{H_3}} \right)}_2}} \right]^{1 + }}\]
D. \[N{H_4}Cl\]

Answer 1

Hint: \[N{H_4}OH\] solution is aqueous ammonia solution which contains \[N{H_3}\] as well as \[{H_2}O\], so on the basis of this question can be easily answered. Also, \[AgCl\] is white colored precipitate solution and becomes colorless when dissolved in aqueous ammonia solution.

Step by step explanation:
Before going directly to the answer, let us first look at the concept behind the question and some information about silver and its salts solubility in \[N{H_4}OH\].
First of all, we must know that \[N{H_4}OH\] is a solution of ammonia in water i.e. liquid ammonia and we are here comparing solubility in liquid solution or called aqueous ammonia.
Now this silver salt i.e. Silver chloride \[AgCl\] is dissolved in it and it is soluble in the solution. This is because of the reaction occurring behind this which is represented as: -
\[AgCl{\text{ }} + {\text{ }}2N{H_4}OH{\text{ }} \to {\text{ }}{\left[ {Ag{{\left( {N{H_3}} \right)}_2}} \right]^{1 + }}\; + {\text{ }}C{l^ - } + {\text{ }}{H_2}O\]
This compound is formed after \[AgCl\] is dissolved in aqueous ammonia, since aqueous ammonia means \[N{H_3}\] in \[{H_2}O\] so this aqueous ammonia will have \[N{H_4}^ + \]and \[O{H^ - }\] ion, so this explains why this complex is formed.
\[AgCl\] is white colored precipitate and when dissolved in aqueous ammonia, it forms colorless solution and this is because of formation of this complex that is explained above.

Additional Information: Other salts of silver like \[AgBr\]and \[AgI\] also raises a question whether they are soluble or not. \[AgBr\] is soluble in concentrated ammonia solution and forms a complex but \[AgI\] is insoluble in ammonia solution. The reason could be explained on the basis of polarization effect and it’s covalent character \[\left( {AgI} \right)\] which makes it insoluble in ammonia solution.
Hence, the correct option is C i.e. \[{\left[ {Ag{{\left( {N{H_3}} \right)}_2}} \right]^{1 + }}\]

Note: To answer similar type of questions, and questions related to solubility and covalent character few elements and its properties must be known and also good knowledge of Fajan’s rule is required which involves polarization effect, covalent character and like in this question, Silver and how it forms complex with different reagents.