Internal Energy in Isothermal and Adiabatic Rxns


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kshalbi
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Internal Energy in Isothermal and Adiabatic Rxns

Postby kshalbi » Fri Jan 15, 2016 10:51 pm

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.

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Re: Internal Energy in Isothermal and Adiabatic Rxns

Postby Chem_Mod » Sat Jan 16, 2016 12:48 am

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
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Re: Internal Energy in Isothermal and Adiabatic Rxns

Postby kshalbi » Tue Jan 19, 2016 3:05 pm

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

Postby Chem_Mod » Tue Jan 19, 2016 5:20 pm

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


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