# THERMO CHEM Heat Cap

## Homework Statement

The problem provides two paths. P1,V1,T1------->P1,V2,T3 (this is the only one i do not understand) for AN IDEAL GAS reversible expansion

Pressure---constant
Volume---not constant
Temperature---not constant

Calculate the q(rev)=? work(rev)=? and ΔU=?

## The Attempt at a Solution

Because the pressure is constant I assumed that Cp(heat [email protected] constant pressure) should be used instead of Cv (heat [email protected] volume)

so...

Work(rev)=∫Cp(T)dT however the book says use ∫Cv(T)dT why is this?

It does not make sense to me because the pressure is constant and the volume changes so why use Cv over Cp Cp=5/2*R Cv=3/2R or is the book stating that the change in volume is so small that we can still use Cv(T).

Any help would be greatly appreciated

Thank you

## Answers and Replies

DrClaude
Mentor
Which book is that?