Question

When excess of silver nitrate solution is added to a beaker containing $200\, mL$ of $0.01\, M$ pentaaquachloridochromium (III) chloride solution, the mass of silver chloride obtained (in $mg$ ) is_____.
[Atomic mass: Chlorine $=35.5\, u$, silver $=108\, u ]$.

Answer 1

$200\, mL$ of $0.01\, M$ solution of the complex contains $0.01 \times 0.200=0.002\, mol$ of complex The chemical formula of pentaaquachloridochromium(III) chloride is $\left[ Cr \left( H _{2} O \right)_{5} Cl \right] Cl _{2}$.
On ionization, one mole of the complex gives two $Cl ^{-}$ions in solution.
$\therefore $ The given solution contains $2 \times 0.002\, mol$ of $Cl ^{-}$ ions $=0.004\, mol$ of $Cl ^{-}$ ions
$AgNO _{3}+ Cl ^{-} \longrightarrow AgCl \downarrow+ NO _{3}{ }^{-}$
$1\, mol Cl ^{-}$ ions $\equiv 1\, mol\, AgCl$
$\therefore 0.004\, mol\, Cl ^{-}$ions $\equiv 0.004\, mol\, AgCl$
$=0.004 \times 143.5$
$=0.574\, g\, AgCl$
$=574\, mg\, AgCl$