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 Sep 2nd 2008, 08:29 PM #1 Senior Member   Join Date: Apr 2008 Location: HK Posts: 886 Graph I saw a p-T graph which has a constant positive slope. Here is a statement: ~The gas volume V is increasing. From the equation pV=nRT, Slope of the p-T graph should represent a constant over volume. With the mass fixed and a constant positive, I don't see why the statement is said to be correct judging from the graph?
Sep 3rd 2008, 01:54 PM   #2

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 Originally Posted by werehk I saw a p-T graph which has a constant positive slope. Here is a statement: ~The gas volume V is increasing. From the equation pV=nRT, Slope of the p-T graph should represent a constant over volume. With the mass fixed and a constant positive, I don't see why the statement is said to be correct judging from the graph?
I we know that V is increasing then the Ideal Gas Law does not predict a straight line for the T vs. p graph. So if the graph is a straight line, then V cannot be increasing.

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 Sep 8th 2008, 06:39 AM #3 Senior Member   Join Date: Apr 2008 Location: HK Posts: 886 I overlook that temperature is in celcius scale. My classmates explained that when T is 0, P/T tends to infinity. When T increases, P/T drops. As PV/T is a constant, V must be increasing. I guess myself would never figure out such kind of logical relationship.....

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