(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

One mole of Ar initially at 325K undergoes an adiabatic expansion against a pressure P_{external}=0 from a Volume of 10.5L to 95.0L. Calculate the final Temperature using Ideal Gas and Van der Waals equations of state. Assume C_{v,m}=(3/2)R.

2. Relevant equations

PV=nRT

P=(RT/Vm-b) - (n^{2}a/v^{2}

3. The attempt at a solution

I assumed Cp,m=20.8 J/mol K and Cv,m=12.47 J/mol K due to the ratios.

Also since it's adiabatic q=0

Initial Volume = 10.5 L

Final Volume = 95.0 L

Using my professors notes for an example of a similar problem I found the equation:

Tf = Ti*(Vm,i / Vm,f)^{gamma}

Gamma - Cp,m/Cv,m . So gamma = 1.4

My math was Tf=325 K * (10.5L/95L)^{0.4}

Tf=135K

My concern is I'm not sure if I won't get full credit since I didnt really use the van der waals equation of state or even the ideal gas law to my knowledge.

Can anyone provide some help?

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# Homework Help: Adiabatic Expansion problem

Can you offer guidance or do you also need help?

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