The vapor pressure of liquid acetone, CH3COCH3, is 40.0 mm Hg at 264 K. A sample
ID: 476316 • Letter: T
Question
The vapor pressure of liquid acetone, CH3COCH3, is 40.0 mm Hg at 264 K. A sample of CH3COCH3 is placed in a closed, evacuated container of constant volume at a temperature of 385 K. It is found that all of the CH3COCH3 is in the vapor phase and that the pressure is 60.0 mm Hg. If the temperature in the container is reduced to 264 K, which of the following statements are correct? Choose all that apply. A. No condensation will occur. B The pressure in the container will be 41.1 mm Hg. C Only acetone vapor will be present. D Liquid acetone will be present. E. Some of the vapor initially present will condense
2)
Use the following vapor pressure data to answer the questions:
Liquid Vapor preesure, torr Temperature C
Fe 10 2040
Bi 10 1060
1) In which liquid are the attractive forces the weakest ? ___BiFe Bi or Fe
(2) Which liquid would be expected to have the lowest heat of vaporization? ___BiFe Bi or Fe
Explanation / Answer
At a given temperature, a substance having higher vapor pressure has a high tendency to vaporize.
At 385 K, the vapor pressure is 60.0 mm Hg,all the acetone has been vaporized
If the temperature is reduced to 264, the vapor pressure falls to 40 mmHg,
The pressure in the container will be 41.1 mm Hg. Liquid acetone will be present. E. Some of the vapor initially present will condense
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The lower the boiling point, the lower the attractive forces between the liquid molecules.So as the boiling point of Bi is lower then the boiling point of Fe, at the same existing pressure.
Thus, Bi liquid has weakest attractive forces.
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heat of vaporization is the amount of heat required to vaporize a given quantity of the substance, if the boiling point is high , then heat of vaporization.
According to trouton rule,heat of vaporization of pure liquids are directly proportional to the absolute temperatures of their boiling points.
Hence, Bi liquid as lower heat of vaporization.
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