Question

For $1$ molal aqueous solution of the following compounds, which one will show the highest freezing point?

• A. $\left[Co\right(H_{2}O{)}_6]C{l}_3$
• B. $\left[Co\right(H_{2}O{)}_{5}Cl]C{l}_2\cdot H_{2}O$
• C. $\left[Co\right(H_{2}O{)}_{5}C{l}_2]Cl\cdot 2H_{2}O$
• D. $\left[Co\right(H_{2}O{)}_{3}C{l}_2]\cdot 3H_{2}O$

Answer 1

Answer: (C)

$\left[Co\right(H_{2}O{)}_{5}C{l}_2]Cl\cdot 2H_{2}O$

Here, the answer is option $C$.
$\left[Co\right(H_{2}O{)}_{5}Cl]C{l}_2.H_{2}Oi=3$
$\left[Co\right(H_{2}O{)}_{6}C{l}_2]C{l}_2.H_{2}Oi=2$
$\left[Co\right(H_{2}O{)}_{3}C{l}_3{]}_3.H_{2}Oi=1$
$\left[Co\right(H_{2}O{)}_{6}C{l}_3]i=4$
$\Delta T_f\propto i$
where $\Delta T_f=(T_f–T_f^{\prime })$
$T_f^{\prime }$ $=$ Freezing point of the solution,
Freezing point of the solution as increased as $"i"$ decreased