Question

Compound $PdC{l}_4.6H_{2}O$ is a hydrated complex. Its 1 molal aqueous solution has a freezing point of $269.28\text{K}$. Assuming 100% ionization of the complex, calculate the molecular formula of the complex. $(K_f$ for water $=1.86{\text{Kkgmol}}^{-1})$

• A. $\left[Pd\right(H_{2}O{)}_6]C{l}_4$
• B. $\left[Pd\right(H_{2}O{)}_{4}C{l}_2]C{l}_2.2H_{2}O$
• C. $\left[Pd\right(H_{2}O{)}_{3}C{l}_3]Cl.3H_{2}O$
• D. $\left[Pd\right(H_{2}O{)}_{2}C{l}_4].4H_{2}O$

Answer 1

The correct option is C $\left[Pd\right(H_{2}O{)}_{3}C{l}_3]Cl.3H_{2}O$

$\Delta T_f=273-269.28=3.87K$
$3.72=i{K}_{f}m=i\times 86\times 1$
$\therefore i=2$
Looking at the options, only option c produces 2 ions in solutiohn - one complex ion and the other - chloride ion.