Question

$PtCl_{4} . 6H_{2}O$ can exist as a hydrated complex 1 molal aq. solution has depression in freezing point of $3.72^{\circ}$ Assume 100% ionisation and $K_{f}(H_{2}O)= 1.86^{\circ}\,mol^{-1}\,kg$, then complex is

• A. $[Pt(H_{2}O)_{6}]Cl_{4}$
• B. $[Pt(H_{2}O)_{4}Cl_{2}]Cl_{2} . 2H_{2}O$
• C. $[Pt(H_{2}O)_{3}Cl_{3}] Cl.3H_{2}O$
• D. $[Pt(H_{2}O)_{2}Cl_{4}].4H_{2}O$

Answer 1

Answer: (C)

$\Delta\,T_{f}=i \times m \times K_{f}$
$i=\frac{3.72}{1.86 \times 1}=2$
So salt is (Pt $(H_{2}O)_{3} Cl_{3}) Cl. 3H_{2}O$