Sulfur dioxide has a vapor pressure of 462.7 mm Hg at -21.0°C and a vapor pressure of 140.5 mm Hg at -44.0°C.What is the molar heat of vaporization of sulfur dioxide? (R = 8.31 J/K⋅mol)

Question

Quizplus · Accepted Answer

We can use the Clausius-Clapeyron equation to solve for the molar heat of vaporization. 
ln(P2/P1) = ΔHvap/R * (1/T1 - 1/T2)
where P1, T1 and P2, T2 are the vapor pressures and temperatures given in the problem, respectively.
Plugging in the values gives:
ln(140.5/462.7) = ΔHvap/8.31 * (1/252 - 1/229)

Solving for ΔHvap gives:
ΔHvap = -R * ln(140.5/462.7) / (1/252 - 1/229)
ΔHvap = 24.9 kJ/mol

Therefore, the answer is D) 24.9 kJ/mol.

Sulfur Dioxide Has a Vapor Pressure of 462