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anonymous
 one year ago
Which of the following must be true for adiabatic processes?
anonymous
 one year ago
Which of the following must be true for adiabatic processes?

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anonymous
 one year ago
Best ResponseYou've already chosen the best response.0A) \(C_v = C_p\) B) \(\Delta H = 0\) C) \(\Delta U = 0\) D) \(\Delta S = 0\) E) \(q=0\)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I put B which is wrong. I don't think any of these answer choices given are right though.

taramgrant0543664
 one year ago
Best ResponseYou've already chosen the best response.0An adiabatic process is one in which no heat is gained or lost by the system.

taramgrant0543664
 one year ago
Best ResponseYou've already chosen the best response.0There is one that is right there

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I agree with you but I think the correct answer should be \(\Delta q = 0\)

JoannaBlackwelder
 one year ago
Best ResponseYou've already chosen the best response.0In an adiabatic change, q = 0, so the First Law becomes ΔU = 0 + w.

taramgrant0543664
 one year ago
Best ResponseYou've already chosen the best response.0Yes it is The first law of thermodynamics with Q=0 shows that all the change in internal energy is in the form of work done. This puts a constraint on the heat engine process leading to the adiabatic condition shown below. This condition can be used to derive the expression for the work done during an adiabatic process.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I thought Q was a constant, so the change in Q is 0. @JoannaBlackwelder why isn't it \(\Delta U = \Delta q + \Delta w \) and \(U=q+w\) ?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@taramgrant0543664 I guess I'm not familiar with this notation, since when I think of adiabatic I think the heat content is not zero but the change in the heat content is 0. Does what I'm asking make sense?

taramgrant0543664
 one year ago
Best ResponseYou've already chosen the best response.0I'm pretty sure ΔU=Δq+Δw is used for isobaric conditions

JoannaBlackwelder
 one year ago
Best ResponseYou've already chosen the best response.0Take a look here: http://www.chem1.com/acad/webtext/energetics/CE2.html#S3A

taramgrant0543664
 one year ago
Best ResponseYou've already chosen the best response.0The a diabetic system doesn't allow heat in or out so its not a change it would be just 0

JoannaBlackwelder
 one year ago
Best ResponseYou've already chosen the best response.0When q is positive, heat is added, when q is negative heat is taken out, and when q is 0 there is no heat transfer.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Well I know what adiabatic means, that's not the problem, I don't think the notation is correct. For example when we substitute in things in the differential form: \[dU=dq+dw\] we can substitute in \[TdS=dq\] or \[pdV=dw\] to get \[dU=TdS+pdV\] But this is different, if you're writing \[dU=q+w\] that's a different thing altogether.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0So what I'm saying is \(\Delta q=0\) should be the correct answer not \(q=0\) because: \(q=0\) means there is no heat content. \(\Delta q=0\) means there is no change in heat content. Which is what adiabatic means to me, since none was transferred. Does this help clear up what I'm asking specifically @JoannaBlackwelder and @taramgrant0543664 ?

taramgrant0543664
 one year ago
Best ResponseYou've already chosen the best response.0I get where you're coming from it is a little confusing I never really looked at it like that

JoannaBlackwelder
 one year ago
Best ResponseYou've already chosen the best response.0The notation q=0 doesn't mean no heat content. It means no change in heat content.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I guess I should just accept that this is what the notation means. In thinking about if the equation was actually \(U=q+w\) (not \(\Delta U\) ) then that would mean the internal energy U is the sum of its internal heat energy q and then what's w? While it might make sense to think of q as the internal heat energy, I guess w is more like potential energy? Or pressure energy? I guess it falls apart to think of it like this. Thanks for your help both of you @taramgrant0543664 and @JoannaBlackwelder I guess I'll try to sort this out a little more on my own unless you have more you'd like to add! :D
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