The vapor pressures of liquid ethanol and liquid 1-propanol were measured at several…
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
The vapor pressures of liquid ethanol and liquid 1-propanol were measured at several temperatures. Selected data are provided.
Temperature (K)
Vapor pressure of ethanol (kPa)
Vapor pressure of 1-propanol (kPa)
298
7.9
2.2
308
13.0
4.1
318
20.9
7.4
328
32.2
12.6
Answer the following questions about the two substances.
(1) (a) Without performing a calculation, identify which of the two liquids has stronger overall intermolecular forces. Cite specific evidence from the data.
(2) (b) Using the data, determine the enthalpy of vaporization, ΔHvap, for ethanol. Clearly outline the graphical or algebraic method you use and include units in your final answer.
(3) (c) Repeat the determination in part (b) for 1-propanol.
(4) (d) Compare the magnitudes of the enthalpies you obtained. Explain how these values are consistent with the predominant intermolecular forces present in each liquid.
(5) (e) At 298K, which liquid is expected to exhibit the larger surface tension? Justify your answer using the enthalpy data and intermolecular considerations.