Nonlinear gas volume/pressure relationship

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Discussion Overview

The discussion centers on the relationship between gas volume and pressure, specifically exploring whether there are gases whose volume increases nonlinearly with a decrease in pressure. The scope includes theoretical considerations, practical implications for real gases, and references to equations that describe these behaviors.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant inquires about the existence of a gas that exhibits a nonlinear increase in volume with decreasing pressure.
  • Another participant asserts that nonlinear relationships are common in real gases and references the Van der Waals equation, which accounts for intermolecular forces and the volume of gas particles.
  • A different viewpoint suggests that a nonlinear relationship could imply rapidly increasing intermolecular forces with compression, particularly if the gas particles are charged.
  • One participant requests information about a table of gases and their volume-pressure values.
  • Another participant responds that while a specific table may not be readily available, graphs plotting pressure versus volume for various gases exist, noting that deviations from ideal behavior are minor in many cases. They recommend looking at compressibility graphs for more informative insights into real gas behavior.

Areas of Agreement / Disagreement

Participants express varying perspectives on the nature of gas behavior under pressure changes, with some agreeing on the applicability of the Van der Waals equation while others introduce alternative considerations regarding intermolecular forces. The discussion does not reach a consensus on the existence of a specific table of gas values or the best graphical representation of gas behavior.

Contextual Notes

The discussion includes assumptions about the behavior of real gases versus ideal gases and the limitations of graphical representations in conveying the complexities of gas behavior under varying conditions.

Who May Find This Useful

Individuals interested in gas laws, real gas behavior, and the mathematical modeling of gases may find this discussion relevant.

stargazer_iq
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is there a gas which its volume increases nonlinearly with decrease in pressure?
 
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A non-linear relation is in fact the most common in practical cases ('real gases', they are called).
A modified equation of the ideal gas equation exists which explains this (it's called the 'Van der Walls gas equation):

(P + an^2/V)(V - nb) = nRT

Here, a and b are constants. 'a' accounts for inter-molecular forces, and 'b' accounts for the volume of the gas atoms themselves.
 
A non-linear relation would imply that the inter-molecular forces increase rapidly with compression, and, this is possible if the gas particles are charged...is that the kind of thing you have on your mind??
 
thanks a lot!
is there a table of gas names and their volume pressure values?
 
I don't know about a table (you could probably find one if you searched on the net enough anyways), but you will be ale to find plenty of graphs plotting P versus V for various gases at different temperatures.
But these probably wouldn't help you too much - because they are inversely proportional, you should be getting a rectangular hyperbola in an ideal case, and the little deviations that would occur for a real gas would not be noticeable, especially because of the peculiar shape of the graph...
A better graph would be one which plots compressibility (represented by the variable 'Z') versus pressure. Now this is a graph from which you can learn a lot, and you can clearly see major deviations of real gases from an ideal case. There's a lot you can learn from this, and it's really extensive, so I suggest you search for it on the net. In fact, if you could log on to ncert.nic.in
That's the website from which you can access all the textbooks used in India for all grades. In Grade 11's Chemistry (Part I) textbook, read the sections on 'Real Gases' in the fifth chapter (titled 'States of Matter')...that should help you a lot - they've written about the stuff really well...


Hope this helps!
 

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