Thermodynamics - know process, work and change in entropy. Final temperature?

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Homework Help Overview

The problem involves a 200-gram sample of dry air being heated isobarically, with a focus on the concepts of work done during expansion and changes in entropy. The original poster seeks to determine the final temperature of the air given specific values for entropy change and work done.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to relate the change in heat (dq) to temperature change (dT) using specific heat capacities, while expressing confusion about the role of initial temperature and mass in the calculations. Other participants suggest using work to find the temperature difference and integrating to find the final temperature, but questions remain about the lack of an initial temperature.

Discussion Status

Some participants have provided guidance on potential approaches to find the final temperature, while others express uncertainty regarding the initial conditions necessary for the calculations. There is no explicit consensus on the method to resolve the problem.

Contextual Notes

The discussion highlights the challenge posed by the absence of an initial temperature, which is critical for solving the problem. Participants are navigating the implications of this missing information while exploring different methods to approach the problem.

HHveluj
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So, the problem is:
A 200-gram sample of dry air is heated isobarically. Its entropy increases by 19.2 J/K and the work done by expansion is 1.61x103 J. Solve for the final temperature of the air.

Okay, since p=const => dq=CpdT thus instead of dq=du+dw we can write
dq=dq(Cv/Cp)+dw
can find dq=460.46
So i know dq,du,dw,d\phi, but how do I get final temperature? All I can find is dT but it's useless sine I don't know initial temperature.
And where do I put mass and how to use the d\phi=dq/T formula? Looks like it will be needed here...

Thanks a lot in advance!
 
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nevermind. solved it.
 
Aw. I have this problem too and I'm stuck on it. :(
 
Get Tfinal - Tinitial through work, then you can solve integral dphi=dq/t and get the answer for Tfinal.
 
I have this problem too and i still do not understand how you can solve for T final if there is not an initial temp given.
 

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