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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.

Respuesta :

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

Explanation:

Depression in freezing point is given by:

[tex]\Delta T_f=i\times K_f\times m[/tex]

[tex]\Delta T_f=7.9^0C[/tex] = Depression in freezing point

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

[tex]K_f[/tex] = freezing point constant = [tex]k^0C/m[/tex]

m= molality

[tex]\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}[/tex]

[tex]7.9^0C=1\times k_f\times \frac{63.4g\times 1000}{75.07g/mol\times 700g}[/tex]

[tex]k_f=6.55^0C/m[/tex]

b) [tex]\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}[/tex]

[tex]13.3^0C=i\times 6.55\times \frac{63.4g\times 1000}{162.2g/mol\times 700g}[/tex]

[tex]i=3.64[/tex]

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