Concise Physical Chemistry

c12 JWBS043-Rogers September 13, 2010 11:27 Printer Name: Yet to Come

200 SOLUTION CHEMISTRY

Problem 12.2

Acetone and chloroform are completely miscible in one another. The partial pressures

of chloroform as a function of the mole fraction in acetone solutions are

X 2 p 2 (kPa)

0.00 0.00

0.20 35

0.40 82

0.67 142

0.80 219

1.00 293

Find the Raoult’s law and Henry’s law activity coefficients of chloroform at 0.20

mole fraction.

Problem 12.3

Derive an expression for the freezing point depression from an equality of Gibbs

potentials.

Problem 12.4

Given that the enthalpy of fusion of water is about 6 kJ mol−^1 , determine the value

of the freezing point constant,Kf.

Problem 12.5

Show that

X 2 =

M 1

1000

m

whereX 2 is the mole fraction of dissolved solute, M 1 is the molar mass of the solvent,

andmis the solute molality, that is, show that

Tb≈

RTb^2 M 1


vapH 11000

m=Kbm

for dilute solutions.

Problem 12.6

In the section on freezing point depression, theCRC Handbook of Chemistry and

Physics,2008–2009, 89th ed., defines the mass % as the mass of solute divided by