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Postby 505095793 » Sun Feb 17, 2019 6:17 pm

If a system has adiabatic walls can we assume q=0 and delta U=w?

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Re: q=0

Postby 305113590 » Sun Feb 17, 2019 6:20 pm

Yes, this is because since temperature is constant. The equations, C∆T and mC∆T have a change in temperature, but adiabatic is constant temperature. Therefore ∆U only is dependent on work of expansion, w.

Sophia Ding 1B
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Re: q=0

Postby Sophia Ding 1B » Tue Feb 19, 2019 1:39 pm

Yes, because if temperature is constant in this type of isolated system, then heat is never lost nor gained. Thus q, heat, is not changing within the system and can be set equal to 0. And because we know that ∆U = q + w, if q = 0 then that leaves ∆U = w.

Ethan Breaux 2F
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Re: q=0

Postby Ethan Breaux 2F » Tue Feb 19, 2019 2:28 pm

They'll usually just say constant temp or isothermal which is pretty much the same thing.

Jasmine Chow 1F
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Re: q=0

Postby Jasmine Chow 1F » Fri Feb 22, 2019 8:18 pm

yes you can assume that q is equal to zero. In this type of reaction, say a piston, the piston moves so quickly it does not allow an exchange of heat with the surroundings therefore there is no heat for an adiabatic system.

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