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- Jul 2, 2008
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Question1:
In a cylinder containing N2 which is insoluble in water, there is a small amount of water at 25 C. At this temp, water has vapor press of 24 mm Hg.
The total press of the cylinder at this temp is 600 mm Hg.
If the volume was reduced to one half, the partial pressure of the gas would be:
a) 2atm
b)1200 mm hg
c) 1176 mm hg
d) 48 mm hg
e) 24 mm hg
ans C
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It seems that the answer is derived by doubling the original pressure minus the 24 mm Hg from the water pressure. 600X2-24=1176mm Hg
My question is why doesn't the water vapor pressure double like the N2 pressure?
I understand that water is relatively incompressible but shouldn't the water vapor which is in gas form be compressed along with the N2 gas and have a pressure double its original?
Question 2:
vapor pressure of water at 100 C is measured on the moon. Compared to vapor pressure on earth at the same temp, the vapor pressure would be:
a)higher
b)lower
c)variable
d)dependant on the time of measurement
e) the same
ans: e) the same
I thought the vapor pressure would be higher on the moon since there's no atmosphere to prevent the water molecules from escaping its liquid phase.
Isn't this like how water boils at much lower temp at higher altitude?
Less atmospheric pressure, thus more water molecules escape and thus higher vapor pressure?
In a cylinder containing N2 which is insoluble in water, there is a small amount of water at 25 C. At this temp, water has vapor press of 24 mm Hg.
The total press of the cylinder at this temp is 600 mm Hg.
If the volume was reduced to one half, the partial pressure of the gas would be:
a) 2atm
b)1200 mm hg
c) 1176 mm hg
d) 48 mm hg
e) 24 mm hg
ans C
------------------------------------
It seems that the answer is derived by doubling the original pressure minus the 24 mm Hg from the water pressure. 600X2-24=1176mm Hg
My question is why doesn't the water vapor pressure double like the N2 pressure?
I understand that water is relatively incompressible but shouldn't the water vapor which is in gas form be compressed along with the N2 gas and have a pressure double its original?
Question 2:
vapor pressure of water at 100 C is measured on the moon. Compared to vapor pressure on earth at the same temp, the vapor pressure would be:
a)higher
b)lower
c)variable
d)dependant on the time of measurement
e) the same
ans: e) the same
I thought the vapor pressure would be higher on the moon since there's no atmosphere to prevent the water molecules from escaping its liquid phase.
Isn't this like how water boils at much lower temp at higher altitude?
Less atmospheric pressure, thus more water molecules escape and thus higher vapor pressure?
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