1.0 $\mathrm{M}$ aqueous solution of $\mathrm{CrCl}_{3} \cdot 6 \mathrm{H}_{2} \mathrm{O}$ freezes at $-5…

1.0 $\mathrm{M}$ aqueous solution of $\mathrm{CrCl}_{3} \cdot 6 \mathrm{H}_{2} \mathrm{O}$ freezes at $-5.58^{\circ} \mathrm{C}$. Assuming complete ionization of the hydrated complex, which of the following isomers conforms to the observation $\left(K_{f}ight.$ for water $=1.86$ $\left.\mathrm{K} \mathrm{kg} \mathrm{mol}^{-1}ight)$ ?
  1. $\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}ight)_{3} \mathrm{Cl}_{3}ight] .3 \mathrm{H}_{2} \mathrm{O}$
  2. $\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}ight)_{4} \mathrm{Cl}_{4}ight] \mathrm{Cl} .2 \mathrm{H}_{2} \mathrm{O}$
  3. $\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}ight)_{5} \mathrm{Cl}ight] \mathrm{Cl}_{2} \cdot \mathrm{H}_{2} \mathrm{O}$
  4. $\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}ight)_{6}ight] \mathrm{Cl}_{3}$

Solution

$\mathrm{i}=\frac{5.58}{1.86}=3 ;$
$\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}ight)_{5} \mathrm{Cl}ight] \mathrm{Cl}_{2} \cdot \mathrm{H}_{2} \mathrm{O} \longrightarrow$
$\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}ight)_{5} \mathrm{Cl}ight]^{2+}+2 \mathrm{Cl}^{-}$ ^

Asked in: JEE-TOPICTESTS-CHEMISTRY

Practice more SOLUTIONS questions on Aicharya