## Cp/Cv

605110118
Posts: 75
Joined: Wed Sep 18, 2019 12:21 am

### Cp/Cv

If an entropy/delta T problem doesn't specifically state it, do we assume it is at constant pressure or constant volume?

SnehinRajkumar1L
Posts: 101
Joined: Thu Jul 11, 2019 12:15 am

### Re: Cp/Cv

You should assume constant pressure.

Shrayes Raman
Posts: 129
Joined: Sat Jul 20, 2019 12:15 am

### Re: Cp/Cv

constant pressure is assumed unless otherwise specified as we have the equation nRT ln(v2/v1) assumes constant pressure

Fatemah Yacoub 1F
Posts: 114
Joined: Thu Jul 11, 2019 12:16 am

### Re: Cp/Cv

You must assume that it is constant pressure because otherwise you a reversible system which requires another set of equations.

stephaniekim2K
Posts: 79
Joined: Fri Aug 09, 2019 12:16 am

### Re: Cp/Cv

Unless stated, just assume that it is at constant pressure.

Posts: 102
Joined: Wed Sep 18, 2019 12:21 am

### Re: Cp/Cv

You can usually assume constant pressure because usually reactions arn't moved to different pressures throughout the course of the reaction. for example a chemist starting a reaction at sea level will probably let the reaction finish at sea level. This is true for most reactions with engines being an exception.

Sjeffrey_1C
Posts: 108
Joined: Wed Feb 20, 2019 12:17 am

### Re: Cp/Cv

Fatemah Yacoub 1F wrote:You must assume that it is constant pressure because otherwise you a reversible system which requires another set of equations.

In this case, you'd use work = -nRT ln (v2/v1)

Callum Guo 1H
Posts: 134
Joined: Fri Aug 02, 2019 12:15 am
Been upvoted: 1 time

### Re: Cp/Cv

i think just assume constant pressure.