Thermodynamics II Pt 2

  1. Constant-Pressure process (or ______ process) (______' law):
    P= ___
    What does this mean for final and initial volume/temperature
    • Isobaric process
    • Charles' law
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  2. With a fixed piston, the system is in _______, pressure must be the same on both sides of the piston
    With a movable piston, because the external pressure doesn't change, the gas pressure remains ________ as the gas expands 
    An isobaric process appears on a pV diagram as a ________ line
    • equilibrium 
    • constant 
    • horizontal line
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  3. An isobaric process is one that occurs at a _______ _______. The values of the heat and the work are generally both _______ values. 
    W = ____ = _______
    p is the ______ ______
    From the First Law: 
    ΔEth = ___ + ___ = ___ - _____
    • constant pressure
    • nonzero
    • W = -Wgas = -p(Vf - Vi)
    • constant pressure
    • ΔEth = Q + W = Q - p(Vf - Vi)
  4. Constant-Volume or ________ Process (________'s law): 
    Vi = ___
    pi/Ti = ___
    As the temperature increases, the pressure __________
    A constant-volume process appears on a pV diagram as a _______ ______
    • Isochoric
    • Guy-Lussac's law
    • Vi = Vf
    • pi/Ti = pf/Tf
    • increases
    • vertical line
  5. Isochoric Process
    An ________ process is one in which there is no change in the volume 
    ΔV = ___ ⇒ W = ____

    From the First Law:
    ΔEth = ____
    • isovolumic process
    • 0
    • Q
  6. Isochoric process
    If energy is added by heat to a system kept at constant volume, all of the transferred energy remains in the system as an increase in its _______ ______
    internal energy
  7. Constant-Temperature Process (or _______ process) are under _______'s law: 
    Ti = ___
    piVi = _____, making it ______
    • Isothermal process
    • Boyle's law 
    • Tf
    • pfVf, making it constant
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  8. An isothermal process appears on a pV diagram as a _______
    • hyperbola 
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  9. An ________ process is one that occurs at a constant temperature. Since there is no change in temperature, ΔEth = ___
    From the First Law: 
    Q = ___
    Any energy that enters the system as heat must leave the system by _____
    • isothermal process
    • 0
    • -W
    • work
  10. The graph of an isothermal process is known as an _______. Different temperatures correspond to different ________
    • isotherm
    • isotherms 
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  11. What is the formula for work done on a ideal gas in an isothermal process?
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  12. Define adiabatic process and state its first law
    • Adiabatic process: a process during which no energy enters or leaves the system by heat, Q = 0
    • First Law: ΔEth = Q + W = W
  13. The curve of the adiabatic compression moves from a _______ ________ isotherm to a ______ _______ isotherm
    • lower temperature isotherm
    • higher temperature isotherm 
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  14. An adiabatic process is one under which  no ______ enters or leaves the system, in other words, no _____ is exchanged with the environment.
    State two ways this is achieved and give an example
    • heat
    • heat
    • Thermally insulating the walls of the system
    • Having the process proceed so quickly that no heat can be exchanged
    • Example: rapidly expanding gas which drops its pressure precipitously and simultaneously cools. This is the principle in a snow-making machine
  15. Free expansion is a unique _______ process. _____ work is done on the gas, W = ___.
    Since Q = ____ and W = ____, ΔEth = ____
    • adiabatic process
    • No work 
    • W = 0
    • Q = 0 and W = 0 
    • ΔEth = 0
  16. In Free expansion, the ______ and ______ energies are the same, and no change in ________ is expected
    • initial and final energies
    • temperature
  17. A ______ process is one that originates and ends at the same state. This process would not be _______ and on a PV diagram, it appears as a _______ ______.
    • cyclic process
    • isolated
    • closed curve
  18. In a cyclic process, the energy added by heat to the system must therefore equal the ________ of the work done on the system during the cycle 
    ΔEint = ____ and Q = ____
    The net work done per cycle  = ?
    • negative 
    • -W
    • The net work done per cycle equals the area enclosed by the path on a PV diagram
  19. Summarize the Q,W and ΔEth different types of processes
    ΔEth = Q+W (6)
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    A.
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    B. solve for T, we know p, V and n is constant
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    B.
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    A.
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    • N = 8 * 1026 atoms of air
    • Power = 50 W
    • Duration = 10 min
    • (energy goes to air particles)
    • p(power)Δt(time) = energy = ΔEth (so this is neither of the 6 processes)
    • ΔEth = 3/2nR(Tf - Ti) *for monatomic gas
    • air is mostly Nitrogen which is diatomic so:
    • ΔEth = 5/2nR(Tf - Ti)
    • pΔt = 5/2nRΔT = 5/2NKBΔT
    • ΔT = 1.09 C
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    see slides then notes
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  27. Define energy reservoir
    Energy reservoir: an object or part of the environment whose temperature does not noticeably change when heat is transferred between the system and itself
  28. Differentiate between a hot and cold reservoir
    as well as QH and QC (what do the Qs have in common?)
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  29. Heat is never spontaneously transferred from a _____ object to a ______ object
    • colder
    • hotter
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  30. A heat engine is a device that is able to take energy from a _____ reservoir, transform some into useful _____, and deposit the rest as ______ energy in a ______ reservoir.
    • hot
    • work
    • thermal energy
    • cold
  31. Label the heat engine 
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    Assume there is no net energy transfer into or out of the heat engine. Thus, 
    QH = ____ + _____
    All quantities are ______
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    • QH = QC + Wout
    • positive
  32. What is the efficiency formula for a heat engine (3)
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  33. QH is what you had to pay (why?)
    No heat engine can operate without exhausting some fraction of the heat into a _____ _______. It is a fundamental law of matter. 
    What is the formula for maximum efficiency (or ______ efficiency) of any heat engine 
    What is the units for temperature
    • because this is the energy of the fuel burned
    • cold reservoir
    • Carnot efficiency
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    • emax = 1 - (TC/TH)
    • A. emax = 1 - (303.15/573.15) = .47108
    • B. emax = 1 - (303.15/523.15) = .4205
    • C. emax = 1 - (293.15/473.15) = .3804 
    • D. emax = 1 - (283.15/373.15) = .2412
    • E. emax = 1 - (273.15/363.15) = .2478
    • ans = A.
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    • emax = 1 - (TC/TH)
    • emax = 1 - (288.15/513.15) = .4385
  36. What is the job of a heat pump?
    Since it is a process against the natural direction, what happens to the system?
    Thus, QH = ?
    All quantities are ______
    • To transfer heat energy from a cold reservoir to a hot reservoir
    • work is done to the system 
    • QH = QC + Win 
    • positive
  37. Label the heat pump
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  38. You can use the heat pump for cooling, e.g. a ________. The ________ _____ _________ (____) is a quantity similar to the efficiency of the heat engine.
    • refrigerator
    • Coefficient of Performance (COP)
  39. State the formula for COP (3) and Maximum COP of a heat pump used for cooling
    What units must temperature be in?
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  40. You can use the heat pump for heating, state an example
    State the formula for both COP (3) and the formula for Maximum COP of a heat pump used for HEATING
    State the units for temperature
    • warming a winter cabin
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  41. Larger COP means a more _______ heat pump! Unlike the efficiency of heat engine (e<1), COP of heat pump can be _______ than 1
    • efficient 
    • greater
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    • COP = Qc/Win
    • COPmax = TC/(TH-TC
    • B. 1 & 4
  43. Label the heat engine (11-story) 
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    **The available arrows are just hints and not all of the actual arrows
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  44. State 4 important characteristics of this heat engine
    (previous card)
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  46. Define entropy
    Natural processes tend to move toward a state of _______ ________. Only _______ energy has entropy
    • Entropy: a measure of the order or disorder of a system
    • greater disorder
    • thermal energy
  47. The ordered, organized motion of the baseball (macroscopic _______ energy) has _____ entropy, while the disorganized random motion of the gas atoms (_______ energy) in a balloon has _____ entropy. 
    State-wise: Entropy of _____ < Entropy of ______ < Entropy of ______
    • kinetic 
    • low 
    • thermal 
    • high 
    • Entropy of solid < Entropy of liquid < Entropy of gases
  48. For a baseball and a balloon, state the the direction and speed of motion of the molecules, the type of motion, and the type of energy
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Author
chikeokjr
ID
344555
Card Set
Thermodynamics II Pt 2
Description
Thermodynamics II Pt 2
Updated