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deeko1987
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Homework Statement
We have
0.0008 Kmol of an ideal gas are expanded from V1 to V2 v2=3V1
process is reversible and T/V=Constant
if the work obtained by this expansion is 9.4 KJ find the initial temperature
R=8.314 KJ Kmol-1
Homework Equations
PV=nRT
possibly T/V = T/V
The Attempt at a Solution
The method I thought to use is as follows.
PV=nRT we know work = 9.4KJ
9.4/nR = T2
T2/V2 = T1/V1
multiply T2/V2 by V1
and we get T2/3 (because the ratio is 1/3)
got 471.092 kelvin for T1
a class mate used this method
PV= 9.4KJ
Pressure is constant as t/v=constant
P(3V1-V1) = 9.4KJ
2PV1= 9.4 KJ (divide by 2)
PV1 = 4.8KJ
PV1=nRT2 = 4.8
solving for t
4.8/nR = 721
T1 = 721 kelvin
Could somebody please explain which method is correct to use and if it is the second method the how this works.In my view the work down at PV1 should not be equal to half the initial work done because the question states the work done expanding from V1 to V2. Also using the second method wouldn't that still be by definition T2 because although we have algebraically modified the
equation we still have T2 in the formula.
Many thanks
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