Question

The freezing point depression of a $1.00\times {10}^{-3}$ molal aqueous solution of $K_x\left[Fe\right(CN{)}_6]$ is $7.35\times {10}^{-3}$. If molal depression constant for water is 1.86 K kg $mo{l}^{-1},$ what is the value of x?

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is C 3

$\Delta T_f=i\times K_f\times m7.35\times {10}^{-3}=i\times 1.86\times 1.00\times {10}^{-3}i=4K_3\left[Fe\right(CN{)}_6]\to 3K^{+}+[Fe(CN{)}_6{]}^{3-}x=3$