{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

problem-solution-6 - Chem 444 Instructor Nancy Makri...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chem. 444 Instructor: Nancy Makri PROBLEM McQ 20-6 Calculate q rev and S for a reversible cooling of one mole of an ideal gas at a constant volume V 1 from P 1 , V 1 , T 1 to P 2 , V 1 , T 4 followed by a reversible expansion at con- stant pressure P 2 from P 2 , V 1 , T 4 to P 2 , V 2 , T 1 (the final state for all the processes shown in Figure 20.3). Compare your result for S with those for paths A, B+C, and D+E in Figure 20.3. Beginning with the first law of thermodynamics: dU q w δ δ = + We recall that for an ideal gas U α T and that for the overall process T i = T f so, 0 dU q w δ δ = = - And with a little more work, 1 2 2 1 1 1 2 2 2 1 0 ( ) V V V rev V V V q w PdV PdV P dV P V V = - = + = + = - It then follows for the entropy that rev dq PdV RdV dS T T V = = = where n = 1 mole as suggested by the problem statement. It then follows that 2 1 1 1 2 1 ln V V V V RdV RdV V S R V V V = + = ÷ The process described in this problem and in Figure 20.3 trace out different paths in PV -space but have the same final and initial points. Hence the heat evolved, being de-
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern