14. Solutions
The Colligative Properties
27PRACTICE PROBLEM
We are given the following values:
Mass Citric Acid (C6H8O7) (g) = 1.708 g
Mass Acetic acid = 10.34 g
Freezing point of pure acetic acid = 16.6°C
Freezing point of citric acid-acetic acid mixture = 13.4 °C
Freezing point constant of acetic acid = 3.9 °C/m
a. Determine the molality in mol/kg of the mixture using the freezing point depression formula
b. Determine the moles of solute present in the mixture using the values of the molality calculated in part a and mass of solvent
c. Determine the experimental molecular weight of the solute in g/mol
d. Determine the theoretical molecular weight of the solute in g/mol
e. Determine the percent error between the theoretical and experimental molecular weight of the solute
We are given the following values:
Mass Citric Acid (C6H8O7) (g) = 1.708 g
Mass Acetic acid = 10.34 g
Freezing point of pure acetic acid = 16.6°C
Freezing point of citric acid-acetic acid mixture = 13.4 °C
Freezing point constant of acetic acid = 3.9 °C/m
a. Determine the molality in mol/kg of the mixture using the freezing point depression formula
b. Determine the moles of solute present in the mixture using the values of the molality calculated in part a and mass of solvent
c. Determine the experimental molecular weight of the solute in g/mol
d. Determine the theoretical molecular weight of the solute in g/mol
e. Determine the percent error between the theoretical and experimental molecular weight of the solute
ANSWERS OPTIONS
A
a. 0.41 m, b, 0.0082 mol, c. 192.1 g/mol d. 192.1 g/mol, e. 0.01%
B
a. 0.85 m, b. 0.0085 mol, c. 201 g/mol, d. 201.3 g/mol, e. 0.01%
C
a. 0.82 m, b. 0.0085 mol, c. 201 g/mol, d. 192.08 g/mol, e. 4.64%
D
a. 0.21 m, b. 0.12 mol, c. 192.1 g/mol, d. 201.3 g/mol, e. 4.64%