Question

When 63.4 g of glycine (C2HNO2 are dissolved in 700. g of a certain mystery liquid X, the freezing point of the solution is 7.9 °C lower than the freezing point of pure X. On the other hand, when 63.4 g of iron(III) chloride are dissolved in the same mass of X, the freezing point of the solution is 13.3 °C lower than the freezing point of pure X Calculate the van't Hoff factor for iron(III) chloride in X.

Answer 1

Answer: The van't Hoff factor for iron(III) chloride in X is 3.64

Step-by-step explanation:

Depression in freezing point is given by:

`\Delta T_f=i* K_f* m`

`\Delta T_f=7.9^0C` = Depression in freezing point

i= vant hoff factor = 1 (for non electrolyte)

`K_f` = freezing point constant =
`k^0C/m`

m= molality

`\Delta T_f=i* K_f* \frac{\text{mass of solute}}{\text{molar mass of solute}* \text{weight of solvent in kg}}`

`7.9^0C=1* k_f* (63.4g* 1000)/(75.07g/mol* 700g)`

`k_f=6.55^0C/m`

b)
`\Delta T_f=i* K_f* \frac{\text{mass of solute}}{\text{molar mass of solute}* \text{weight of solvent in kg}}`

`13.3^0C=i* 6.55* (63.4g* 1000)/(162.2g/mol* 700g)`

`i=3.64`

Thus the van't Hoff factor for iron(III) chloride in X is 3.64