## Isothermal expansion

isochoric/isometric: $\Delta V = 0$
isothermal: $\Delta T = 0$
isobaric: $\Delta P = 0$

Chloe Alviz 1E
Posts: 102
Joined: Sat Aug 17, 2019 12:17 am

### Isothermal expansion

Why is ∆U = 0 for isothermal expansion (or compression) of an ideal gas?

Posts: 74
Joined: Fri Sep 28, 2018 12:29 am

### Re: Isothermal expansion

One of the characteristics of an ideal gas is that there is no interaction between gas molecules. This means the molecules will not have any potential energy so the only contributor to the change in internal energy would be its kinetic energy due to its absolute temperature. Since it is isothermal, T=0 so neither kinetic nor potential energy would contribute to the change in internal energy so deltaU=0.

Jared Khoo 1G
Posts: 107
Joined: Wed Sep 18, 2019 12:16 am

### Re: Isothermal expansion

Delta U is equivalent to 3/2 NKB(Delta T), so if T is constant then Delta U is constant as well.

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