## isothermal = no internal energy change

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

Kyung_Jin_Kim_1H
Posts: 53
Joined: Thu Jul 27, 2017 3:00 am

### isothermal = no internal energy change

If there is no change in temperature/system is isothermal, does it imply no change in internal energy? Since deltaU=q+w and q=mCdeltaT, I get that q=0 if change in temperature is 0. I don't understand how w=0 as well though.

Rachel Brown 3A
Posts: 52
Joined: Fri Sep 29, 2017 7:06 am

### Re: isothermal = no internal energy change

for isothermal reactions, delta U = 0 which means that q=-w. however, it does not necessarily mean that q=0. Even though temperature is the same, heat can and will still be transferred to counter the work being done so that the internal energy remains at 0. q is only 0 is the system is "adiabatic." Hope this helps!

Helen Shi 1J
Posts: 78
Joined: Sat Jul 22, 2017 3:00 am

### Re: isothermal = no internal energy change

Is delta U zero for all reversible reactions or just isothermal?

Kevin Ru 1D
Posts: 50
Joined: Thu Jul 13, 2017 3:00 am

### Re: isothermal = no internal energy change

I believe it applies to just isothermal reactions.

Justin Lai 1C
Posts: 50
Joined: Fri Sep 29, 2017 7:04 am

### Re: isothermal = no internal energy change

Only isothermal reactions have u = 0 so q = -w. T being 0 does not always mean that q = 0. Isothermal reaction is when T = 0. This is because as work may be done by or done on the system, there is a supply or removal of heat from the system so that T = 0 and that the internal energy of the system remains constant.

Adiabatic is when q = 0. Here T does not equal 0. This means that there is a change in internal energy.