# If excess of AgNO_"3" solution is added to 100 ml of 0.024 M solution of dichlorobis (ethylene diamine) cobalt (III) chloride, how many moles of AgCl will be precipitated??

Aug 10, 2017

$\text{0.0024 mols}$ of $\text{AgCl}$.

Well, this is just a regular limiting reactants problem, with more complicated compounds. The only hurdle is figuring out what the dichlorobis(ethylenediamine)cobalt(III) charge is.

Dichlorobis(ethylenediamine)cobalt(III) chloride has:

• two chloro ligands (${\text{Cl}}^{-}$) in the inner coordination sphere.
• two ethylenediamine ligands (${\text{H"_2"N"-"CH"_2-"CH"_2-"NH}}_{2}$) in the inner coordination sphere.
• a chloride (${\text{Cl}}^{-}$) ligand coordinated on the outer coordination sphere.
• cobalt(III), which has an oxidation state of... what is $\text{III}$ in english?

The oxidation states add up as:

${\overbrace{2 \times \left(- 1\right)}}^{\text{dichloro" + overbrace(2 xx 0)^("bis"("en")) + overbrace((+3))^"cobalt(III)}} = \left(+ 1\right)$

Thus, it is written as...

overbrace(["CoCl"_2("en")_2])^(+1)"Cl"

The cis form is shown below.

The ethylenediamine ligands are bidentate, $\sigma$ donor, strong-field ligands, so it is likely that this complex is a low-spin complex, making it relatively inert in the inner coordination sphere.

So, the reaction is probably going to be an outer-sphere, double-replacement reaction:

${\text{AgNO"_3(aq) + ["CoCl"_2("en")_2]"Cl"(aq) -> "AgCl"(s) + ["CoCl"_2("en")_2]"NO}}_{3} \left(a q\right)$

The complex is clearly the limiting reactant, so...

$\text{0.024 mol/L" xx "0.100 L" = "0.0024 mols complex}$

The complex is $1 : 1$ with $\text{AgCl}$, so $\underline{\boldsymbol{\text{0.0024 mols}}}$ of $\text{AgCl}$ will be generated.