Solving Part B of PV=NkbT: An Explanation

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SUMMARY

The discussion focuses on solving Part B of the equation PV=NkbT, specifically addressing the calculation of entropy change using the Boltzmann Constant. The user successfully calculated the number of atoms (N) as 2.446*10^22 using given values for pressure, volume, and temperature. However, they encountered a problem with the calculation of the macrostate, as it resulted in an undefined logarithm due to the volume raised to the power of N being effectively zero. Participants emphasized the importance of understanding the relationship between microstates and macrostates in the context of entropy calculations.

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  • Understanding of the ideal gas law (PV=NkbT)
  • Familiarity with the concept of entropy and its relation to microstates and macrostates
  • Knowledge of logarithmic functions, particularly ln(0) and its implications
  • Basic principles of statistical mechanics
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  • Review the derivation of entropy in statistical mechanics
  • Learn about the relationship between microstates and macrostates in thermodynamics
  • Study the implications of logarithmic functions in physical equations
  • Explore advanced topics in statistical mechanics, such as the canonical ensemble
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Students studying thermodynamics, physics enthusiasts, and anyone tackling problems related to statistical mechanics and entropy calculations.

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Homework Statement



"see attachment"

Homework Equations



PV=NkbT
Change in entropy = Boltzmann Constant x In(Macrostate)

The Attempt at a Solution



for part A, I knew that PV=NKbT

giving that pressure is 101300Pa volume is 1*10^-3 m^3, Kb is 1.38*10^-23 and T=300K
I find N to be 2.446*10^22 atoms


the problem I have is with part B

the question states that microstate is proportion to V^N where N is the number of atom I found in part A, and V is the volume which is 1*10-9 m^3. Thus V^N is a very small number which is pretty much zero. Change in entropy = Boltzmann Constant x In(Macrostate), since Macrostate is zero, there is an error in this calculation. Since In(0) is undefined. What am I suppose to do in this question??
 
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I forgot to attach the question, here it is
 

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Hi Junkwisch!

Always in physics things are only big or small relative to other things. The numerical value of V^N depends entirely on what units you're using.

Perhaps you can simplify \ln\left(V^N\right) without making an approximation? :smile:
 
Junkwisch said:
Change in entropy = Boltzmann Constant x In(Macrostate)
You should check that you have the correct relationship here. How can the left side of the equation be a change when there's no corresponding change present on the righthand side of the equation? Also, what is "Macrostate" supposed to represent?
 

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