## Gas Expansion

$\Delta S = \frac{q_{rev}}{T}$

Rita Chen 1B
Posts: 112
Joined: Sat Jul 20, 2019 12:15 am

### Gas Expansion

In Dr. Lavelle's lecture, can someone explain why if delta U is 0, why the gas expands?

Naji Sarsam 1F
Posts: 104
Joined: Sat Aug 17, 2019 12:18 am

### Re: Gas Expansion

Dr. Lavelle's lecture pertained specifically to isothermic reversible expansion. In this type of expansion, the delta U equals 0. This is because isothermal reactions mean that once energy is used in the form of work, the system gains that energy back as heat to maintain the same temperature--thus the net energy change is 0.

DLee_1L
Posts: 103
Joined: Sat Aug 17, 2019 12:17 am

### Re: Gas Expansion

Plus, there are certain scenarios when the system is isothermal and thus delta U is equal to 0 such as when the gas expands in a container with a piston (with no pressure being exerted) and in a vacuum, therefore there is no work or heat transfer.

Dan M -3E
Posts: 101
Joined: Wed Sep 18, 2019 12:19 am

### Re: Gas Expansion

Gas always spontaneously expands when put into a larger container, and never contracts into a space smaller than all available.