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Laws of Thermodynamics 1

Laws of Thermodynamics 1. Disusun Oleh : Ichwan Aryono, S.Pd. First law of thermodynamics. First Law of thermodynamics states that :

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Laws of Thermodynamics 1

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  1. Laws ofThermodynamics 1 Disusun Oleh : Ichwan Aryono, S.Pd.

  2. First law of thermodynamics First Law of thermodynamics states that : Whenever heat Q is given to a system, a portion of heat is used to increase its internal energy in the amount of DU, whereas the remaining leaves the system when the system performs a work W to its surroundings. Mathematically, the first law of thermodynamics is formulated by : Q = DU + W Q>0 W positip jika sistem melakukan usaha W negatip jika sistem dikenai usaha Q positip Jika sistem menerima kalor Q negatip jika sistem melepas kalor Energi dalam DU tidak terpengaruh oleh proses, yang dilihat adalah hanya pada keadaan awal dan keadaan akhir W>0 W<0 Q<0

  3. The first law of thermodynamics for isothermal process At isothermal Process : DT = 0, so DU = 0 The work done by the isothermal process is : Q = DU + W = 0 + W = W Q =

  4. The first law of thermodynamics for isobaricprocess At isobaric process the pressure is constant DP = 0 Internal energy , so

  5. The first law of thermodynamics for isochoric process At Isochoric process volume is constant, DV = 0, so the work done W = PDV = 0, its produce :

  6. The first law of thermodynamics for adiabatic process Adiabatic process is a process without any transfer of heat into or from the system (Q=0)and it applies :

  7. Student Activity #1 A system absorbs 1500 J of heat from surrounding and does work done 2200 J . Determine the change of internal energy system, increases or decreases ?

  8. Student Activity • Mention three general variables of thermodynamics

  9. What is state function ?

  10. Why is the internal energy classified as a state function, meanwhile work and heat is not classified as a state function ?

  11. Can we warm up of a soap without giving any additional amount of heat to the soup ? Explain it

  12. A work can be done into a system at a constant pressure, heat can also be tranferred to a system at a constant volume. Is it possible to transfer heat to a system while maintaining the temperature of the system constant ? Explain it

  13. A diatomic in a closed container has an initial temperature of 250oC, a pressure of 105 N/m2, and a volume of 5 L. The gas undergoes an isobaric process to a pressure of 2 x 105 N/m2. a. Describes the process above in a P-V diagram b. Find the change in its internal energy c. find the total work done by the gas

  14. Student Activity • Mention three general variables of thermodynamics • What is state function ? • Why is the internal energy classified as a state function, meanwhile work and heat is not classified as a state function ? • Can we warm up of a soap without giving any additional amount of heat to the soup ? Explain it • A work can be done into a system at a constant pressure, heat can also be tranferred to a system at a constant volume. Is it possible to transfer heat to a system while maintaining the temperature of the system constant ? Explain it

  15. Student Activity #2 System absorbs 1500 J of energy from surrounding. At the same time 2200 J work done is given to the system. Determine the change of internal energy of the system. Is temperature decreses or increases ?

  16. Student Activity #3 Two mol of ideal gas is expans from point I to point F with three difference way as shown in diagram below. Calculate the work done, change of internal energy, and calor in each way IAF, IF and IBF, state in joule P(atm) A 4 I B F 1 V(L) 2 4

  17. Student Activity P(Pa) Four mol of ideal gas in cylinder container change its conditional as shown in graphic P-V beside. Determine the work done, internal energy and calor if the gas is change from A to C thrue (a) ABC, (b) AC A B 500 C 200 V(cm3) 0 800 500 300

  18. Quiz (work in pairs) • Three different processes act on system. • In process A, 42J of work are done on the system and 77J of heat are added to the system. Find the change in the system’s internal energy. • b. In process B. the system does 42 J of work and 77J of heat are added to the system. What is the change in the system’s internal energy ? • c. In process C, the system’s internal energy decreases by 120 J while the system performs 120 J of work on its surroundings. How much heat was added to the system ?

  19. Student Activity #6 An ideal gas is taken through the four processes shown in figure below. The changes in internal energy for three of these processes are as follows : DUAB = + 82 J, DUBC = +15 J, DUDA = -56 J. Find the change in internal energy for the process from C to D D C pressure A B volume

  20. Student Activity # 7 a. Find the work done by a monoatomic ideal gas as it expands from point A to point C along the path shown in figure below. b. If the temperature of the gas is 220K at point A, what is its temperature at point C ? c. How much heat has been added to or removed from the gas during this process ? B 600 400 Pressure P(kPa) A C 200 Volume, V(m3) 0 2 4 6 8 10

  21. Student Activity #8 • During an adiabatic process, the temperature of 3.52 moles of monoatomic ideal gas drops from 485oC to 205oC. For this gas, find • The work it does • The heat it exchanges with its surroundings, and • The changes in internal energy

  22. Student Activity #9 • An ideal gas follows the three-part process shown in figure below. At the completion of one full cycle, find • The net work done by the system • The net change in internal energy of the system • The net heat absorbed by the system A 150 Pressure P(kPa) 100 B 50 C 1 2 0 3 4 Volume, V(m3)

  23. Quiz • Suppose 57.5 moles of an ideal monoatomic gas undergoes the series of processes shown in figure below. • Calculate the temperature at the points A, B, and C. • For each process, A-B, B-C, and C-A, state whether heat enters or leaves the system, Explain in each case. • Calculate the heat exchanged with the gas during each of three process. A 150 Pressure P(kPa) 100 B 50 C 1 2 0 3 4 Volume, V(m3)

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