Charles, Gay-Lussac and of course Boyle

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Discussion Overview

The discussion revolves around the application of gas laws, specifically focusing on how to derive an equation that relates volume, pressure, and temperature when all variables are changing. The context includes exploring the combined gas law and its implications under varying conditions.

Discussion Character

  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant expresses difficulty in finding an equation for variable initial and final temperature, pressure, and volume.
  • Another participant suggests the equation P1V1/T1 = P2V2/T2 as a potential solution, though they express uncertainty about their memory of the concept.
  • A third participant reiterates the same equation and confirms its validity under the assumption that the number of moles remains constant.
  • A fourth participant introduces the combined gas law, stating that it can be expressed as P1V1T2 = P2V2T1, which simplifies the earlier equations by eliminating fractions.

Areas of Agreement / Disagreement

Participants appear to agree on the relevance of the combined gas law and the conditions under which it applies, but there is no consensus on a single equation that addresses the original query about variable conditions.

Contextual Notes

Assumptions regarding the constancy of moles are noted, but the discussion does not resolve how to handle cases where temperature, pressure, and volume all vary simultaneously.

susan__t
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I'm having a little bit of an issue trying to find an equation to use when the initial and final temperature, pressure and volume are all variable

I know [tex]\frac{V1}{T1}[/tex] =[tex]\frac{V2}{T2}[/tex]

and [tex]\frac{P1}{T1}[/tex] =[tex]\frac{P2}{T2}[/tex]

and P1V1=P2V2

But I want to combine them so that I can get the V2 when the Pressure and Temperature 1 and 2 both vary.
 
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maybe P1V1/T1 = P2V2/T2 ? Sorry I used to know this but i can't seem to remember
 
susan__t said:
maybe P1V1/T1 = P2V2/T2 ? Sorry I used to know this but i can't seem to remember

If I understood your question accurately ... yes , assuming that the moles are constant.
 
The combined gas law states that when moles are constant, P1V1T2=P2V2T1 (basically what has been said above, but getting rid of those fractions).
 

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