Question

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A 10-L drum of ether at 18C is open to the atmosphere (p=760 Torr) and contains 6-L of liquid. The top is sealed and the drum dented so that it now has an 8-L capacity.If the vapor pressure of the ether at 18C is 400 Torr, What is the pressure inside the dented sealed drum? Can you please show work and explain. Thanks

Answer 1

Given that

Initially , a 10-L drum containing 6 L of ether at 18C is open to the atmosphere ( P = 760 torr )

Volume of gasses inside the drum = ( 10 L - 6 L ) = 4 L

Total pressure of gasses inside the drum = Atmospheric Pressure = 760 torr

Partial pressure of ether = 400 torr

Partial pressure of air = ( 760 torr - 400 torr ) = 360 torr

Immediately , when the drum is sealed and dented to 8 L Volume.

Volume of gas inside the drum = ( 8 L - 6 L ) = 2 L

Total pressure of gas inside the drum = 760 torr x ( 4 L / 2 L ) = 1560 torr

Hence,

Partial pressure of ether should be = 400 Torr x 2 = 800 torr

Partial pressure of air should be = 360 Torr x 2 = 720 torr

But some of the ether vapor will condensed into liquid ( to keep vapor pressure of ether at 400 torr )

Then,

the final total pressure should be = [ 400 torr ( from ether ) + 720 torr ( from air ) ] = 1120 torr

Therefore,

pressure inside the dented sealed drum = 1120 torr