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The vapor pressure of liquid octane, CgII18, is 40.0 mm ITg at 318 K A sample of

ID: 104231 • Letter: T

Question

The vapor pressure of liquid octane, CgII18, is 40.0 mm ITg at 318 K A sample of CH1s is placed in a closed, evacuated container of constant volume at a temperature of 484 K. It is found that all of the CHis is in the vapor phase and that the pressure is 50.0 mm Hg. If the temperature in the container is reduced to 318 K, which of the following statements are correct? Choose all that apply The pressure in the container will be 40.0 mm I1g. Only octane vapor will be present Some of the vapor initially present will condense. DLiquid octane will be present. No condensation will occur.

Explanation / Answer

According to Gay-lusaccs law Pressure of a gas is directly proportional to temperature at constant volume.  

Hence in the above situation as the temperature is lowered pressure is also lowered.

I,e # pressure decreases to 40mm Hg

At lower pressure the force of attraction between the molecules of gases donot increase appreciably hence no liquefaction I,e no condensation. Hence

#there is only octane vapour

# no condensation occur

All these statements are true.