Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Revision on thermodynamics

9,706 views

Published on

Published in: Education, Technology, Business
  • DOWNLOAD FULL BOOKS, INTO AVAILABLE FORMAT ......................................................................................................................... ......................................................................................................................... 1.DOWNLOAD FULL. PDF EBOOK here { https://tinyurl.com/y6a5rkg5 } ......................................................................................................................... 1.DOWNLOAD FULL. EPUB Ebook here { https://tinyurl.com/y6a5rkg5 } ......................................................................................................................... 1.DOWNLOAD FULL. doc Ebook here { https://tinyurl.com/y6a5rkg5 } ......................................................................................................................... 1.DOWNLOAD FULL. PDF EBOOK here { https://tinyurl.com/y6a5rkg5 } ......................................................................................................................... 1.DOWNLOAD FULL. EPUB Ebook here { https://tinyurl.com/y6a5rkg5 } ......................................................................................................................... 1.DOWNLOAD FULL. doc Ebook here { https://tinyurl.com/y6a5rkg5 } ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... .............. Browse by Genre Available eBooks ......................................................................................................................... Art, Biography, Business, Chick Lit, Children's, Christian, Classics, Comics, Contemporary, Cookbooks, Crime, Ebooks, Fantasy, Fiction, Graphic Novels, Historical Fiction, History, Horror, Humor And Comedy, Manga, Memoir, Music, Mystery, Non Fiction, Paranormal, Philosophy, Poetry, Psychology, Religion, Romance, Science, Science Fiction, Self Help, Suspense, Spirituality, Sports, Thriller, Travel, Young Adult,
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • You can now be your own boss and get yourself a very generous daily income. START FREE...■■■ https://tinyurl.com/make2793amonth
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here

Revision on thermodynamics

  1. 1. Revision on Thermodynamics
  2. 2. First Law of Thermodynamics <ul><li>Statement: </li></ul><ul><li>Energy can not be created or destroyed and the total energy of a system is always constant. </li></ul><ul><li>Mathematical formula for a closed system: </li></ul><ul><li>∆ U = Q + W </li></ul><ul><li>Where; </li></ul><ul><li>∆ U: change in internal energy </li></ul><ul><li>Q: heat transferred to the system. </li></ul><ul><li>W: work done by the system. </li></ul>
  3. 3. First Law of Thermodynamics <ul><li>Sign convention: </li></ul><ul><li>If energy transferred to the system as q or w: </li></ul><ul><li>Q = +ve, W = +ve </li></ul><ul><li>If energy transferred from the system as q or w: </li></ul><ul><li>Q = -ve, W = -ve </li></ul>
  4. 4. First Law of Thermodynamics <ul><li>Recall: </li></ul><ul><li>- System </li></ul><ul><li>The part of the universe that we will study. It is separated from its surroundings by boundaries. </li></ul><ul><li>System may be: </li></ul><ul><li>a. Open ; mass & heat can transfer </li></ul><ul><li>b. Closed ; no mass transfer </li></ul><ul><li>c. Isolated ; no mass or heat transfer </li></ul>
  5. 6. First Law of Thermodynamics <ul><li>Internal Energy </li></ul>
  6. 7. First Law of Thermodynamics <ul><li>Work: </li></ul><ul><li>work arising from a change in volume. </li></ul><ul><li>work done by a gas as it expands and drive back the atmosphere. </li></ul><ul><li>dw = -P ext .dV </li></ul><ul><li>For reversible process: dw = - PdV </li></ul><ul><li>P = system pressure </li></ul>
  7. 8. First Law of Thermodynamics <ul><li>Heat: </li></ul><ul><li>Q = m C ∆T or Q = n C ∆T </li></ul><ul><li>C = specific heat ( J/mol. K) , (J/gm. K) </li></ul><ul><li>C v = specific heat at constant volume </li></ul><ul><li>C p = specific heat at constant pressure </li></ul>
  8. 9. First Law of Thermodynamics <ul><li>Molar heat capacity: </li></ul><ul><li>energy of one mole of a substance. (J/mol. K). </li></ul>
  9. 10. First Law of Thermodynamics <ul><li>Enthalpy: H = U + PV </li></ul><ul><li>Heat content at constant pressure. </li></ul><ul><li>∆H = </li></ul><ul><li>∆H = n Cp ∆T; if Cp is independent on T </li></ul>
  10. 11. Ideal gas processes ( rev process) <ul><li>For different processes: </li></ul>n C p ∆T n C v ∆T n Cv ∆t Zero Adiabatic n C p ∆T n C v ∆T - P.ΔV -nR ∆T n Cp ∆T= ∆H Isobaric n C p ∆T n C v ∆T Zero n Cv ∆T= ∆U Isochoric Zero Zero -Q nRT ln(V f /V i )= nRT ln (P f /P i ) Isothermal ∆ H ∆ U W Q
  11. 12. First Law of Thermodynamics <ul><li>PVT Relation: (for ideal gas) </li></ul><ul><li>Isothermal : PV = const. </li></ul><ul><li>Isobaric: V/T = Const </li></ul><ul><li>Isochoric: P/T = Const </li></ul><ul><li>Adiabatic: T 2 /T 1 = (V 1 /V 2 ) γ-1 </li></ul><ul><li>P 1 V 1 γ = P 2 V 2 γ ; C P /C V = γ </li></ul><ul><li>C P – C V = R </li></ul>
  12. 13. Sheet (1) <ul><li>A sample containing of 1.0 mole of argon expands isothermally at 0º C from 22.4 dm 3 to 44.8 dm 3 . Calculate Q, W, ΔU, and ΔH if the gas expands: </li></ul><ul><li>reversibly </li></ul><ul><li>against a constant external pressure equal to the final pressure of the gas </li></ul><ul><li>freely </li></ul>
  13. 14. Sheet (1) <ul><li>2. The constant pressure heat capacity of a sample of a prefect gas was found to vary with temperature according to the expression: </li></ul><ul><li>C P / (J/K) = 20.17 + 0.3665T </li></ul><ul><li>Calculate Q, W, ΔU, and ΔH when the temperature is raised from 25ºC to 200ºC : </li></ul><ul><li>(a) at constant pressure, </li></ul><ul><li>(b) at constant volume. </li></ul>
  14. 15. Sheet (1) <ul><li>3. An ideal gas undergoes the following sequences of mechanically reversible processes in a closed system; </li></ul><ul><li>a) From an initial state 70°C and 1 bar, it is compressed adiabatically to 150° C. </li></ul><ul><li>b) It is then cooled from 150° to 70°C at constant pressure. </li></ul><ul><li>c) Finally, it is expanded isothermally to its original state. </li></ul><ul><li>Calculate W, Q, ΔU, and ΔH of each of the three processes and for the entire cycle. Take Cp = (5/2)R and Cv = (3/2) R </li></ul>
  15. 16. Second Law of Thermodynamics <ul><li>Direction of energy : </li></ul><ul><li>A spontaneous process is a process in which the final state is more probable than the initial state. </li></ul><ul><li>Every system which is left to itself will, on average, change toward a system of maximum entropy. </li></ul>
  16. 17. Second Law of Thermodynamics <ul><li>Entropy definition: </li></ul><ul><li>A measure of disorder of the system. </li></ul><ul><li>ΔS is equal to the heat Q it absorbs, divided by T. </li></ul>
  17. 18. Second Law of Thermodynamics Zero Reversible adiabatic Cp ln (T 2 /T 1 ) - R ln( P 2 /P 1 ) Any Process Cv ln (T 2 /T 1 ) Isochoric Cp ln (T 2 /T 1 ) Isobaric nR ln (V 2 /V 1 ) Isothermal ∆ S Process
  18. 19. Sheet 1 <ul><li>4. A 40 kg casting (Cp= 0.5 kJ/kg k ) at of 450° C is quenched in a 150 kg of oil (Cp= 2.5 kJ/kg k) at 25° C. if there are no heat losses, what is the change in entropy of the casting, the oil, and both considered together. </li></ul>
  19. 20. Third Law <ul><li>Law of zero entropy </li></ul><ul><li>S (at any T) = S° (at 298 K) + </li></ul>
  20. 21. Sheet 1 <ul><li>5. Calculate the absolute entropy for water at 400 K, knowing that Cp(liq)=75.29 J/mol K, and Cp(vap) =28.85+0.012 T+ (0.1×10 6 ) /T 2 . Knowing that the standard entropy for water equal 69.91 J/mol K and heat of vaporization ΔHv =44.016 kJ/mol. </li></ul>
  21. 22. Thermodynamic equilibrium <ul><li>S is a measure of equilibrium during reversible adiabatic process or isentropic process. </li></ul><ul><li>To define equilibrium in process other than isentropic process we use free energies. </li></ul>
  22. 23. <ul><li>Gibbs free energy </li></ul><ul><li>G = H – TS </li></ul><ul><li>H = total energy </li></ul><ul><li>TS = unavailable energy </li></ul><ul><li>dG = VdP – SdT = fn ( P, T) </li></ul><ul><li>∆ G = 0 at constant T and P </li></ul><ul><li>∆ G = -ve (The process will be spontaneous) </li></ul>
  23. 24. <ul><li>Isothermal Process: </li></ul><ul><li>dG = VdP ∆G = RT ln(P 2 /P 1 ) </li></ul><ul><li>Isobaric process: </li></ul><ul><li>dG= -SdT ∆G= ʃ- SdT </li></ul><ul><li>Isochoric Process: </li></ul><ul><li>∆ G = VdP - ʃ- SdT </li></ul>
  24. 25. <ul><li>Helmholtz free energy </li></ul><ul><li>A = U – TS </li></ul><ul><li>U = Total energy </li></ul><ul><li>TS = unavailable energy </li></ul><ul><li>dA = -PdV – SdT </li></ul><ul><li>∆ A = 0 at constant V and T </li></ul><ul><li>G = H – TS = U + PV- TS = A + PV </li></ul><ul><li>∆ G = ∆A + ∆ (PV) </li></ul>
  25. 26. Sheet 1 <ul><li>6. Calculate ΔG, ΔA, and ΔS for each of the following processes: </li></ul><ul><li>a) Reversible melting of 36 gm of ice at 1 atm and 0°C. </li></ul><ul><li>b) Reversible vaporization 39 gm of C 6 H 6 at its normal boiling point of 80 </li></ul>
  26. 27. Sheet 1 <ul><li>7. A sample consisting of 1 mole of argon is taken through the following cyclic process: </li></ul><ul><li>a) Isobaric expansion at 1 atm from 25 to 50 liters. </li></ul><ul><li>b) Isochoric cooling at 50 liters from 1 to 0.5 atm. </li></ul><ul><li>c) Isothermal compression to the initial state. </li></ul><ul><li>Calculate ΔU, ΔH,∆S ΔG, ΔA for each step and for the cycle. Argon may be considered ideal gas with C v =3/2R, C p =5/2R </li></ul>
  27. 28. Thank you

×