Open vs. Closed Internal Energies

Moderators: Chem_Mod, Chem_Admin

905373636
Posts: 62
Joined: Thu Aug 01, 2019 12:15 am

Open vs. Closed Internal Energies

Postby 905373636 » Fri Jan 31, 2020 1:30 pm

Today, we talked about in class that in an open system with an exothermique rxn there is expansion work being done.

If it was a closed system, is there no expansion work? Though pressure isn’t constant?

Emma Popescu 1L
Posts: 105
Joined: Wed Sep 11, 2019 12:16 am

Re: Open vs. Closed Internal Energies

Postby Emma Popescu 1L » Fri Jan 31, 2020 2:58 pm

The energy of a closed system can be changed by heating/cooling or compression/expansion. So Change in U=q + w. But if the change in volume is 0 (constant volume) then there is no expansion work.

asannajust_1J
Posts: 105
Joined: Wed Sep 11, 2019 12:16 am
Been upvoted: 1 time

Re: Open vs. Closed Internal Energies

Postby asannajust_1J » Fri Jan 31, 2020 3:52 pm

If the system is closed a change in volume can still occur in the case of a gas doing work on a piston. In an isolated system, there would be no change in volume.

Vincent Leong 2B
Posts: 207
Joined: Fri Aug 09, 2019 12:15 am

Re: Open vs. Closed Internal Energies

Postby Vincent Leong 2B » Fri Jan 31, 2020 4:32 pm

In an closed system, it is more obvious if there's a change in volume or not as there will ussually be a lid that is pushed on by a piston. If in a closed system, they dont mention a initial volume or a volume change, then we can definitively say that work is 0. In an open system, it's sort of similar in that the gas in the container is pushing against something less physically visible. Now, the gas is pushing against air which does exist in the container but is commonly overlooked because we can't see it.


Return to “Thermodynamic Systems (Open, Closed, Isolated)”

Who is online

Users browsing this forum: No registered users and 2 guests