## Internal Energy in Isothermal and Adiabatic Rxns

$\Delta U=q+w$

kshalbi
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### Internal Energy in Isothermal and Adiabatic Rxns

Why is it that in an isothermal rxn delta U=0 and in an adiabatic one, delta U=w? I thought that isothermal and adiabatic were similar conditions.

Chem_Mod
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### Re: Internal Energy in Isothermal and Adiabatic Rxns

Isothermal means deltaT=0 therefore deltaU=0 as well as deltaH=0.

Adiabatic means q=0 so all you can say is that U=w

kshalbi
Posts: 68
Joined: Fri Sep 25, 2015 3:00 am

### Re: Internal Energy in Isothermal and Adiabatic Rxns

Doesn't adiabatic mean that something is thermally insulating, so if it insulates, doesn't that mean that no heat is escaping so there is no change in internal energy?

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### Re: Internal Energy in Isothermal and Adiabatic Rxns

If there is no temperature change then there is no internal energy change. But there can be no heat transferred yet still be a temperature change because work was done. Hence U=w in adiabatic process