Editing Van der Waals equation of state
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One can re-write the van der Waals equation given above as a [[virial equation of state]] as follows: | One can re-write the van der Waals equation given above as a [[virial equation of state]] as follows: | ||
:<math>Z := \frac{pV}{nRT} = \frac{1}{1- \frac{ | :<math>Z := \frac{pV}{nRT} = \frac{1}{1- \frac{nb}{V}} - \frac{an}{VRT} </math> | ||
Using the well known [http://mathworld.wolfram.com/SeriesExpansion.html series expansion] <math>(1-x)^{-1} = 1 + x + x^2 + x^3 + ...</math> | Using the well known [http://mathworld.wolfram.com/SeriesExpansion.html series expansion] <math>(1-x)^{-1} = 1 + x + x^2 + x^3 + ...</math> | ||
one can write the first term of the right hand side as <ref>This expansion is valid as long as <math>-1 < x < 1</math>, which is indeed the case for <math> | one can write the first term of the right hand side as <ref>This expansion is valid as long as <math>-1 < x < 1</math>, which is indeed the case for <math>nb/V</math> </ref>: | ||
:<math>\frac{1}{1- \frac{ | :<math>\frac{1}{1- \frac{nb}{V}} = 1 + \frac{nb}{V} + \left( \frac{nb}{V} \right)^2 + \left( \frac{nb}{V} \right)^3 + ... </math> | ||
Incorporating the second term of the right hand side in its due place leads to: | Incorporating the second term of the right hand side in its due place leads to: | ||
:<math>Z = 1 + \left( b -\frac{a}{RT} \right) \frac{n}{V} + \left( \frac{ | :<math>Z = 1 + \left( b -\frac{a}{RT} \right) \frac{n}{V} + \left( \frac{nb}{V} \right)^2 + \left( \frac{nb}{V} \right)^3 + ...</math>. | ||
From the above one can see that the [[second virial coefficient]] corresponds to | From the above one can see that the [[second virial coefficient]] corresponds to | ||
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:<math>B_{3}(T)= b^2 </math> | :<math>B_{3}(T)= b^2 </math> | ||
==Boyle temperature== | ==Boyle temperature== | ||
The [[Boyle temperature]] of the van der Waals equation is given by | The [[Boyle temperature]] of the van der Waals equation is given by |