Delta U

$\Delta U=q+w$

Moderators: Chem_Mod, Chem_Admin

Ashley Kenney 1E
Posts: 32
Joined: Wed Nov 14, 2018 12:23 am

Delta U

When is $\Delta U=0$?

Mona Lee 4L
Posts: 60
Joined: Fri Sep 28, 2018 12:16 am

Re: Delta U

DeltaU = q + W. Therefore, the internal energy of a system does not change only when q and W are zero.

maldonadojs
Posts: 57
Joined: Fri Sep 28, 2018 12:27 am

Re: Delta U

Delta U is 0 when you are dealing w a isothermal/reversible reaction.

Tuong Nguyen 2I
Posts: 71
Joined: Fri Sep 28, 2018 12:26 am
Been upvoted: 1 time

Re: Delta U

Well delta U can still have a nonzero value at isothermal, reversible processes depending on what w is. So when we know that the system undergoes an isothermal, reversible process, we know that heat (q) = 0 and therefore the only thing left for delta U to equal is w.

So at isothermal, reversible processes, delta U = work (w).

Kavvya Gupta 1H
Posts: 35
Joined: Fri Sep 28, 2018 12:21 am

Re: Delta U

delta u is zero when there is no temperature change

Nicole Elhosni 2I
Posts: 62
Joined: Fri Sep 28, 2018 12:28 am

Re: Delta U

Since for an ideal gas the internal energy is proportional to temperature, it follows that there is no change in the internal energy of the gas during an isothermal process.

Maya_Peterson1C
Posts: 62
Joined: Fri Sep 28, 2018 12:28 am

Re: Delta U

The internal energy is zero when it is a reversible reaction or if it is at a constant temperature.

Niveda_B_3I
Posts: 60
Joined: Fri Sep 28, 2018 12:24 am

Re: Delta U

The change in internal energy could be 0
if q = -w
if T = 0
and if the system is isothermal and the reaction is reversible

Jacob Bershatski 4C
Posts: 30
Joined: Fri Sep 28, 2018 12:21 am

Re: Delta U

Based on the equation, deltaU=(3/2)nR(deltaT), deltaU is 0 when deltaT is 0. I am still a little confused about this myself. However, whenever you have an isolated system, deltaU always equals 0 because heat and work cannot be transferred into or out of the system.

Return to “Concepts & Calculations Using First Law of Thermodynamics”

Who is online

Users browsing this forum: No registered users and 1 guest