# How to visualize entropy in thermodynamics

1. Nov 10, 2006

### vijay123

entropy is the measure of disorder....but i jsut cannot visualize it in a practical standpoint...i mean...the disorder taking place with soo many particles when heated and yet all i know is that s=q/t....can anyone explain this concept better to me?

one more question...how does one prove using statistical mechanics that
s=(boltzmann's constant)lnw....were w is the number of macrostates...

i was tryng to do calculus based entropy probelms...but can do them in refrence to s=(boltzmann's constant)lnw, by counting the number of macrostates available??

and is it possible to find th number of macrostates by equating (boltzmann's constant)lnw=q/t....is this a very large number?

2. Nov 10, 2006

### Reshma

Entropy of a composite system is given by:
S* = SA + SA'-----(1)
Number of accessible states to A* is:
W* = WAWA'------(2)

S*,SA, SA' are entropies of composite system A*, A and A' respectively(A* composed of A and A').
The entropy is a "state" function.
For (1) & (2) to hold good simultaneously, what should be the nature of this function?

3. Nov 10, 2006

### quasar987

W in S=klnW is the number of microstates.

I was indtroduced to entropy through S=klnW as the definition, therefore it's not provable. What definition of S do you use??

4. Nov 10, 2006

### Andrew Mason

Use the thermodynamic definition of entropy and forget about the concept of disorder: dS = dQ/T

AM

5. Nov 10, 2006

### Tomsk

You'll need to use the definition of temperature $$\frac{1}{k_{B}T} = \frac{\partial\ln\Omega}{\partial U}$$ as well.

6. Nov 10, 2006

### Tomsk

...though you might want to show where that comes from, it might be kinda easy otherwise...