2.25 moles of N2 in a state defined by Ti = 300. K and Vi = 1.00 Lundergoes an i
ID: 685800 • Letter: 2
Question
2.25 moles of N2 in a state defined by Ti = 300. K and Vi = 1.00 Lundergoes an isothermal reversible expansion until Vf = 20.5 L.Calculate w assuming (A) that the gas is described by the ideal gaslaw and (B) that the gas is described by the van der Waals equationof state. What is the percent error in using the ideal gas lawinstead of the van der Waals equation?(A) Using the gas law equation, I got the correct answer of w=-1.7 x 103 J
(B) Parameters for N2 gas: a= 1.370 dm6 bar mol-2 ; b= 0.0387dm3 mol-1 I did not know how to use the van der Waals equation to findwork. I started with w= - Pe (Vf- Vi). Is that the correct startingpoint?
(A) Using the gas law equation, I got the correct answer of w=-1.7 x 103 J
(B) Parameters for N2 gas: a= 1.370 dm6 bar mol-2 ; b= 0.0387dm3 mol-1 I did not know how to use the van der Waals equation to findwork. I started with w= - Pe (Vf- Vi). Is that the correct startingpoint?
Explanation / Answer
Substitute the equation of state in for P, then integrate andplug in the bumbers Addn: You know the van der waals gives pressure of a real gas, Youknow that dw=-PdV so from there you plug the wan der walls eqn in for P From there to get w you integrate w/ respect to V Then you just plug in your a, b, T, and initial and finalmolar volumes into the new formula that you've derived for w.Related Questions
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