Elastic Balloon Filled with Ideal Gas

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Discussion Overview

The discussion revolves around the behavior of an elastic balloon filled with an ideal gas when the temperature is increased. Participants explore the implications of this temperature change on pressure and volume, considering the properties of the balloon and the gas laws involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents the ideal gas law, suggesting that increasing the temperature of the gas in an elastic balloon would lead to a doubling of volume, assuming the balloon can expand freely.
  • Another participant argues that if the balloon stretches according to Hooke's law, the pressure remains constant while the volume doubles, implying a specific relationship between pressure and volume as the balloon expands.
  • A different viewpoint suggests that if the volume increases by a factor of √2, the pressure must also increase by √2, indicating a direct relationship between changes in volume and pressure in a closed system.
  • One participant challenges the assumptions made, stating that without additional equations or information about the properties of the balloon and heat flow, it is impossible to definitively determine how volume changes with temperature.

Areas of Agreement / Disagreement

Participants express differing views on how the volume and pressure of the gas in the balloon respond to an increase in temperature. There is no consensus on the exact relationship between these variables, and the discussion remains unresolved.

Contextual Notes

Participants highlight the need for additional equations or information regarding the properties of the balloon and the nature of heat flow to fully understand the system's behavior. The discussion reflects uncertainties regarding the assumptions made about the balloon's elasticity and the ideal gas behavior.

lluke9
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This is the equation I'm talking about:
PV = nRT

So say I had a bit of Ideal Gas in a completely insulated elastic balloon, and I raised a temperature just a little bit.
PV = nR(2T)

Because this is an elastic balloon, would the volume also double?
P(2V) = nR(2T)

But what if the balloon is really tight? Would the pressure increase because the volume couldn't expand as much? But to what extent? How much would the balloon expand?
(?P)(?V) = nR(2T)
There has to be a sort of limit, depending on the stretchiness of the balloon, right?
 
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For a balloon that stretches ideally according to Hooke's law, I believe it resists with a constant pressure, meaning you would see the volume doubling.

That is, because the surface increases with the square of the radius, the stretching force also increases with the square of the radius.
But the resulting pressure, which is the quotient of the two, remains constant.
 
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Say the volume of the balloon increased by √2, then the pressure inside of the balloon would have to increase by √2.

Look at it this way because the balloon is a closed system (xP)(yV) = nR(zT)

x · y = z

if you double z, then x and y have to change so that their product also doubles.
 
Last edited:
You have one equation, PV = nRT - or, the version I think with, P = NT - and three variables: P, V or N, and T. Specifying a change to one does not specify how the other two change, you need another equation. Something about the properties of the container (Hooke's law spring), something about heat flow, whatever - but without more information you cannot say what happens to V if you double T.
 

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