When excess of silver nitrate solution is added to the aqueous solution containing 0.1 mole of `CoCl_3 . xNH_3`, if 28.7g of silver chloride precipitated, what is the value of x ?

Explanation

Number of moles of AgCl precipitated `=(28.7)/(143.5)=0.2` mole.
0.1 mole of `CoCl_(3).xNH_(3)` gives 0.2 mole `AgCl`. One mole of `CoCl_(3).xNH_(3)` gives 2 moles of AgCI.
Thus in the complex `CoCl_(3).xNH_(3)` two chloride ions satisfy only primary valence. One chloride ion satisfies both secondary valence and primary valence.
Since the secondary valence of `Co^(3+)` is six and one `Cl^(-)` is in coordination sphere, complex possesses five `NH_(3)` . Thus .x. value is five.