## Constant Pressure and Volume

Sophia Dinh 1D
Posts: 100
Joined: Thu Jul 25, 2019 12:15 am

### Constant Pressure and Volume

what is the difference in calculation of a constant pressure system vs a constant volume system?

AronCainBayot2K
Posts: 101
Joined: Fri Aug 30, 2019 12:17 am

### Re: Constant Pressure and Volume

Cp=DeltaH/Delta T and Cv=DeltaU/Delta T. Calculations can also vary depending on if the atom is monoatomic, linear, etc this is when dealing with Cv,m and Cp,m.

Abhi Vempati 2H
Posts: 104
Joined: Fri Aug 09, 2019 12:17 am

### Re: Constant Pressure and Volume

Adding on to what was said above, in constant pressure systems, we typically have to account for expansion work, but in constant volume systems, we don't (the gas can't expand if there's no volume change). Hope this helps!

Betania Hernandez 2E
Posts: 107
Joined: Fri Aug 02, 2019 12:15 am

### Re: Constant Pressure and Volume

Calculations vary for monoatomic gases since Cv is 3R/2 under constant volume and Cp is 5R/2 under constant pressure.

Alondra
Posts: 36
Joined: Tue Feb 26, 2019 12:15 am

### Re: Constant Pressure and Volume

Constant pressure: for monatomic it’s 5R/2; for diatomic it’s 7R/2

Constant volume: for monatomic it’s 3R/2; for diatomic it’s 5R/2

Areli C 1L
Posts: 95
Joined: Wed Nov 14, 2018 12:19 am

### Re: Constant Pressure and Volume

Alondra wrote:Constant pressure: for monatomic it’s 5R/2; for diatomic it’s 7R/2

Constant volume: for monatomic it’s 3R/2; for diatomic it’s 5R/2

I addition to this, Organic Chemistry tutor has an entire video dedicated to this topic.

Nathan Rothschild_2D
Posts: 131
Joined: Fri Aug 02, 2019 12:15 am

### Re: Constant Pressure and Volume

Why is the calculation for monatomic atoms lower than that of diatomic atoms.