Use this information to determine benzaldehyde’s vapor pressure (in torr) at 50.5°C.

Question

The heat of vaporization for benzaldehyde is 48.8 kJ/mol, and its normal boiling point is 451.0 K. Use this information to determine benzaldehyde’s vapor pressure (in torr) at 50.5°C. Report your answer to three significant digits.

Answer 1

Use the Clausius Clapeyron equation

ln(P1/P2) = −ΔHvap/R(1/T1 - 1/T2)

P1 = 1 atm

P2 = ?

T1 = 451.0K

T2 = 50.5 + 273 = 323.5K

ΔH_vap = 48.8 kJ/mol

R = 8.314 J/mol K

Plug in the numbers and solve for P2