A `0.01m` aqueous solution of `K_(3)[Fe(CN)_(6)]` freezes ar `-0.062^(@)C`. What is the apparent percentage of dissociation? `[K_(f)` for water `= 1.86]`

Answer

`77.7%`

Explanation

`DeltaT_(f)"(observed)"=0.062^(@)C`
`DeltaT_(f)"(calculated)"=K_(f)xxm=1.86xx0.01=0.0186^(@)C`
`therefore" "i=(DeltaT_(f)"(observed)")/(DeltaT_(f)"(calculated)")=(0.062)/(0.0186)=3.33`
`{:(,""K_(3)[Fe(CN)_(6)]hArr3K^(+)+[Fe(CN)_(6)]^(3-)),("Initial "," 1 mol "),("After disso."," "1-alpha" "3alpha " "alpha " Total "= 1+3alpha):}`
`therefore" "i=(1+3alpha)/(1) or alpha=(i-1)/(3)=(3.33-1)/(3)=0.777=77.7%`.