Chapter 17, Problem 109AE

Interpretation Introduction

Interpretation:

The mass percent of in a 20 g mixture of sucrose and NaCl needs to be deduced along with the mole fraction of sucrose in the mixture.

Concept Introduction:

Empirical formula is a formula that gives the simplest whole number ratio of atoms in a compound.

Molecular formula = n(Empirical formula) ----(1)

  $\text{n = }\frac{\text{Moelcular formula mass}}{\text{Empirical formula mass}}$

The depression in freezing point ( ${\text{ΔT}}_{\text{f}}$ ) of a solution in the presence of a solute of molality ( m ) is given as:

  $\begin{array}{l}{\text{ΔT}}_{\text{f}}{\text{ = T}}_{\text{f}}^{\text{0}}-{\text{ T}}_{\text{f}}\\ {\text{ΔT}}_{\text{f}}{\text{=i(K}}_{\text{f}}\text{×m) -----(2)}\end{array}$

Here,

  ${\text{T}}_{\text{f}}^{\text{0}}$ and ${\text{T}}_{\text{f}}$ are the freezing points of the pure solvent and solution respectively.

K_f denotes the freezing point depression constant.

i represents the Von’t Hoff factor.