- #1

Urmi Roy

- 753

- 1

## Homework Statement

So as a part of a very long question on homework for thermodynamics, I and some of my friends got into a debate about how to write an expression for entropy at a particular state.

## Homework Equations

delS(state 1 to 2)= Cv*ln(T2/T1)+R*ln(V2/V1)

(from constitutive relation for entropy change in an ideal gas)

## The Attempt at a Solution

**Is is correct to say S1 (absolute value of entropy of a gaseous system in state 1)= Cv*ln(T1)+R*ln(V1)?**

I don't think so, coz y

__ou can't really calculate the absolute value of entropy ...unless you take the absolute zero temperature as reference state__...in which case the above expression would contain -(Cv*ln(T0)+R*ln(V0))...and you'd still be taking 'change' in entropy rather than an 'absolute value.