Calculate the depression in the freezing point of a solution containing 0.1 g of `K_(3)[Fe(CN)_(6)]` in 100 g of `H_(2)O` ? (molecular weigth of `K_(3)[Fe(CN)_(6)]=329, K_(f)=1.86K " kg mol"^(-1)`)

Options

A. 0
B. 1.223
C. 0.0226
D. 0.226

Answer

C

Explanation

Given,
Mass of `K_(3)[Fe(CN)_(6)]=0.1g`
Mass of solvent `= 100 g`
Molar mass of `K_(3)[Fe(CN)_(6)]=329g "mol"^(-1)`
`k_(f)=1.86K kg//"mol"`
`K_(3)[Fe(CN)_(6)] hArr 3K^(+)+Fe(CN)_(6)]^(-)`
`i` (van.t Hoff factor ) `=3 + 1=4`
From, depression in freezing point,
`T_(f)=i xxK_(f)xxm`
`T_(f)=4xx1.86K "kg/mol" xx (0.1g)/(329g)xx(1000)/(100 kg)`
`T_(f)=0.226 K`
Thus, option (c) is correct.