# Finding Entropy

1. Jun 18, 2014

### Junkwisch

1. The problem statement, all variables and given/known data

"see attachment"

2. Relevant equations

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

3. 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??

2. Jun 18, 2014

### Junkwisch

I forgot to attach the question, here it is

#### Attached Files:

• ###### Question2.png
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3. Jun 20, 2014

### Oxvillian

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?

4. Jun 20, 2014

### vela

Staff Emeritus
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?