Question:
3 moles of metal complex with formula $\mathrm{Co}(\mathrm{en})_{2} \mathrm{Cl}_{3}$ gives 3 moles of silver chloride on treatment with excess of silver nitrate. The secondary valency of Co in the complex is___________.
(Round off to the nearest integer)
Solution:
$3\left[\mathrm{Co}(\mathrm{en})_{2} \mathrm{Cl}_{2}\right] \mathrm{C} \ell+\underset{\text { (excess) }}{\mathrm{AgNO}_{3}} \rightarrow \underset{\text { (white ppt.) }}{3 \mathrm{AgCl}}$
Secondary valency of $\mathrm{Co}=6$
(C. N.)