Question

The number of ions per mole of a complex \[\left[ CoC{{l}_{2}}.5N{{H}_{3}} \right]C{{l}_{2}}\] in aqueous solution will be
A. Nine
B. Four
C. Three
D. Two

Answer 1

Hint: \[\left[ CoC{{l}_{2}}.5N{{H}_{3}} \right]C{{l}_{2}}\]is a coordination compound. Coordination compounds retain their identity in an aqueous solution but do not provide all the ions that are provided by the constituent compounds. In a solution, the complex will dissociate only with its associated ions.

Complete answer:Coordination compounds are those in which the main metal atom forms a coordination bond with a number of ligands, such as ions or neutral molecules, through which these ligands give the main metal atom lone pairs of electrons.
A complex ion is a chemical that has either a positive or negative charge. Therefore, compounds that include complex ions might be referred to as coordination compounds. Contrary to double salts, these complex ions are rather stable and retain their identity in aqueous solutions.

In the given complex, \[{{\left[ CoC{{l}_{2}}.5N{{H}_{3}} \right]}^{2+}}\]is acting as the cation and it will remain undisturbed in the solution. In the compound\[\left[ CoC{{l}_{2}}.5N{{H}_{3}} \right]C{{l}_{2}}\], the positive part that is the cation \[{{\left[ CoC{{l}_{2}}.5N{{H}_{3}} \right]}^{2+}}\]is bounded ionically to two chloride ions.
Thus after dissolving it in solution it dissociates as shown:

\[\left[ CoC{{l}_{2}}.5N{{H}_{3}} \right]C{{l}_{2}}{{\left[ CoC{{l}_{2}}.5N{{H}_{3}} \right]}^{2+}}+2C{{l}^{-}}\]

Hence, we can infer that \[\left[ CoC{{l}_{2}}.5N{{H}_{3}} \right]C{{l}_{2}}\]gives 3 ions in the aqueous solution, that is 1 cation \[{{\left[ CoC{{l}_{2}}.5N{{H}_{3}} \right]}^{2+}}\]and 2 anions that are chloride ions.

Hence, the correct option is C. Three

Note: Coordination compounds come under the category of additional compounds
Crystals of new substances known as extra compounds separate out when a solution created by combining two or more simple stable chemicals in simple stoichiometric proportions is allowed to evaporate. Double salts are another kind of addition compound in addition to coordination compounds. Double salts, in contrast to coordination compounds, are only stable in their crystallised state and lose their identity when they are dissolved.