Question

The correct order of the stoichiometries of $AgCl$ formed when $AgN{O_3}$in excess is treated with the complexes:$CoC{l_3}.6N{H_3},{\rm{ }}CoC{l_3}.5N{H_3},{\rm{ }}CoC{l_3}.4N{H_3}$respectively is:
(A) $2AgCl,\;3AgCl,\;1AgCl$
(B) $1AgCl,\;3AgCl,\;2AgCl$
(C) $3AgCl,\;1AgCl,\;2AgCl$
(D) $3AgCl,\;2AgCl,\;1AgCl$

Answer 1

We know that stoichiometry deals with the measurements of reactants and products involved in a chemical reaction. First determine which element is replacing the other element then only it will be easy to identify the final product.

Complete Step by step answer: In coordination complex, the secondary and primary valency is important to define so that the reaction can be predicted. Primary valency is the valency of the metal ion in the coordinate complex. The secondary valency is the number of ligands which are attached to the central metal ion. The coordination number is the same as that of the secondary valency. The oxidation state of the metal is the same as that of the metal.
Let us consider a general reaction.
Wherein aA (g) + bB (g) → cC (g) + dD (g)
Here, ‘a’ moles of A(g) reacts with ‘b’ moles of B(g) to give ‘c’ moles of C(g) and ‘d’ moles of D(g). The number of Cl atoms not in the coordinate complexes are free to precipitate as $AgCl$. $Co$forms a complex with $6$ligands with $N{H_3}$ molecules.

Similarly $CoC{l_3}.6N{H_3}$,$3Cl$ will precipitate out,$CoC{l_3}.5N{H_3}$,$2Cl$ will precipitate $CoC{l_3}.4N{H_3}$,$1Cl$ will precipitate.

$$CoC{l_3}.6N{H_3} = [Co{(N{H_3})_6}]C{l_3}\\\ \Rightarrow [Co{(N{H_3})_6}]C{l_3} + 3AgN{O_3} \to [Co{(N{H_3})_6}]{(N{O_3})_3} + 3AgCl \downarrow .\\\ \Rightarrow CoC{l_3}.5N{H_3} = [Co{(N{H_3})_5}Cl]C{l_2}\\\ \Rightarrow [Co{(N{H_3})_5}Cl]C{l_2} + 2AgN{O_3} \to [Co{(NH{l_3})_5}Cl]{(N{O_3})_2} + 2AgCl \downarrow .\\\ \Rightarrow CoC{l_3}.4N{H_3} = [Co{(N{H_3})_4}C{l_2}]Cl\\\ \Rightarrow [Co{(N{H_3})_4}C{l_2}]Cl + AgN{O_3} \to [Co{(N{H_3})_4}C{l_2}]N{O_3} + AgCl \downarrow .$$

In the first reaction the chloride ions will be replaced by the nitro ligand and three moles of silver chloride is obtained.
In the second reaction the chloride ions will be replaced by the nitro ligand and two moles of silver chloride is obtained.
In the third reaction the chloride ions will be replaced by the nitro ligand and one moles of silver chloride is obtained.

Hence, the answer is (D)

Note: The Werner’s theory is used for explaining the naming, coordination number and oxidation state of the coordination compound. Magnetic properties shape and directional orientation of the orbitals cannot be explained.