How to calculate temperature of expanded ideal gas.

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By definition an ideal gas in a closed follows the relationship of PV=nRT, or PV/T = constant

This means that Pressure * Volume/ Temperature will be the same at the start and end of the process. 

So P1V1/T1=P2V2/T2

Assuming that we have a gas at a temperature of 300k (T1) in a piston initially at 1m(V1) which is then expanded at constant pressure (isobaric) to 2m3.(V2) What would be the final temperature?

As Pressure is the same at the start and end of the process, we can ignore the pressure terms, giving

V1/T1=V2/T2

Rearranging the equation to give a solution to T2

T2=V1*T1/V2

Thus filling in the terms we already know, gives

T2=1*300/2

T2=150k

Iain C. IB Physics tutor, GCSE Physics tutor, GCSE Maths tutor

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