Physical chemistry Test 1

  1. Work Formula
  2. Work Units
    kg m^2/s^2
  3. Kinetic Energy
    .5 mu^2
  4. Relatino betwene work and energy
    w = E_kf-E_ki
  5. Kinetic Energy
    Energy posessed by a body by virtue of being in mostion
  6. Potential ENergy
    Energy posessed by a body by virtue of position
  7. System
    A specific segmentof hte world with deffinite boundaries on which we focus our attention
  8. Surroundings
    The part of the world immediately surrounding a system
  9. Universe
    System and its surroundings
  10. Open system
    Can transfer heat and material
  11. Closed system
    Can only transfer heat
  12. Isolated system
    Can transfer neither heat nor matter
  13. Intensive property
    Not a function of quantity
  14. Extensive propety
    Directly a function of quantity
  15. Equation of state
    An equation that describes the condition of a system as a function of intensive properties
  16. Equilibrium
    The systems variables of state are not changing with respect to time
  17. Heat
    The kinetic energy of molecualr motion
  18. Zeroeth law of thermodynamics
    • If A and B are in thermal equilibrium
    • And B and C are in thermal Equilibrium
    • Then A and C are in thermal Equilibrium
  19. Boyles Law
    Applies under Isothermic Conditrions. If temperature and nubmer of mols are held constant then PV=Constant
  20. Isotherm
    Temperature is held constant
  21. Isobaric
    Pressure is held constant
  22. Gay-Lussacks Law
    If Pressure and mols are fixed then V/T =Constant
  23. m is?
  24. M is?
    Molar Mass
  25. Ideal Gas Law
  26. 3 Assumptions of ideal gas law
    • 1) gas is assumed to be composed of individual particles whose actual dimensions are small in comparison to the distance between them.
    • 2) These particles are in constant motion and therefore have kinetic energy.
    • 3) Neither attractive nor repulsive forces exist between the particles.
  27. N
    Number of molecules present
  28. Pressure in terms of mean square speed
    P=Image Upload 1
  29. Average Kinetic Energy of a molecule in a system
    e=.Image Upload 2
  30. Partial Pressure
    Pressure exerted by a single component of a gas mixture. Defined by molar fraction* pressure total
  31. Grahms law of Effucsion
    RImage Upload 3
  32. Collision frequency
    • How many collisions pe second does a molecule experieince
    • units : 1/s
  33. Collision Density
    • How many colisions per unit of second per volume occur?
    • Image Upload 4
  34. Mean free path
    • How far a molecule travels before a collision
    • distnace Image Upload 5
  35. ump
    Most probable velocity. Peak of maxwell curve
  36. z
    • Compression factor
    • =Image Upload 6
  37. z>1
    Repulsive forces dominate (b term from nonideal gas)
  38. Z<1
    Attractive forces dominate (a term)
  39. Van Der Waals equation
    Uses a to account for attraction and b to account for repulsion
  40. Adiabatic
    No change in Heat (Q)
  41. Terms in the maxwell constant of dN/Ndu
    Normalization factor: Image Upload 7

    • Boltzman distribution: Image Upload 8
    • Incremental volume: Image Upload 9
  42. Boltzman distribution
    • Image Upload 10)
    • Maps likely distribution of particle velocities
  43. Incremental volume
    • 4\Image Upload 11
    • Accoutns for incremental volume in maxwell distribution sphere
  44. Maxwell normalization factor
    • NOrmalizes maxwell distribution by total molecules likely to be present
    • Image Upload 12
  45. Image Upload 13
    • Average speed of a molecule in system given by maxwell normalization factor. Actually less common than Image Upload 14
    • Formula: Image Upload 15
  46. Image Upload 16
    Least common of the important speeds in maxwell distribution, this is the root mean square speed.
  47. Average kinetic energy per molecule formula and function of
    • e=Image Upload 17=.5mu2
    • This is a function primarilly of temperature.
  48. When u is not velocity, what is it? (fucking headache)
    • Internal energy: the internal energy of a molecule is the sum of its heat and work
    • u=q+w
  49. First law of thermodynamics
    Energy can neither be created nor destroyed. Only moved.
  50. What are the Five macroscopic properties
    Pressure, Temperature, Volume, Mass, Enegy
  51. What are state functions?
    The macroscopic properties that define a substance
  52. What happens if we fix 3 of the state functions
    The other two are then known
  53. What is path dependence?
    A path dependent function is dependent on how one reaches a point. Using a mountain analogy: Height to reach a point is always constant, distance is a function of the route you take to reach tehat point.
  54. Are state functions path dependent?
    No. They are not. It is part of what makes them state functions.
  55. Equilibrium states
    Points at which without an external operator acting, a system will hold in a steady state over time.
  56. 3 Criteria for equilibrium state
    The mechanical properties, chemical properties and temperature throughout a system must be uniform for something to be in an equilibrium state
  57. Reversible vs Irreversible processes
    If a system is changed slowly enough to maintain an equilibrium state, it is considered a reversible process.
  58. Sign convention for heat (q)
    If a system absorbs heat, q is positive. If a system loses heat, q is negative
  59. Sign convention for work on a system (w)
    • If work is done on a system (work flows in), then w is positive
    • If work is done by a system (work flows out), then w is negative.
  60. q
    • Heat of system. function ot work and internal energy
    • q=Image Upload 18
  61. What can we know about internal energy of a system over an operation
    Its change. We do not know how much internal energy a system posesses, only how much it changes over time
  62. What type of properties are heat and work
    Path properties. They are dependent entirely on path and not functions of state. they are inexact integrals.
  63. Nature of intenral energy (u): What are the 3 things that contribute
    • 1) kinetic energy of motion of hte individual molecules
    • 2) Potential eneryg that arise form interactions between molecules
    • 3) Kinetic and potential energy of nuclei and elctorns with inthe individual molecules.
  64. What are the four types of work
    • Chemical: energy of breaking chemical bonds
    • Elctrical: Work performed by current
    • Mechanical : Gross work of physical motion of masses
    • Osmotic: Transportation and concentration of chemicals
  65. What is work defined as?
    A force over distance. IE ENERGY
  66. How do we define reversible work in thermodynamics? (Form and two notes)
    wrev=-\Image Upload 19

    • Note that if P is not constant, we must deffine it as a function of volume before doing this calculation.
    • Note that dv implies an infintessimal volume change.
  67. Is more work done through reversible or irreversible processes? What do graphs look like?
    • If a process is reversible, it requires more work to do because pressure is assumed constant constant and graph of change is curved.
    • If a process is irreversible, then less work is required as both pressure and volume are assuemd to change. Graph is straight drop of pressure and the straight change of volume.
  68. Which type of process(Reversible or irreversible ) generates more heat? Why?
    • We assume inc U to be constant.
    • With this as a given and the realization that Image Upload 20
    • there will be more heat generated by irreversible work because there is less actual work done.
  69. What is formula and assumption of irreversible work?
    • Irreversible work is assumed to happen suddenly. Too suddenly to be considered incremental. As such, we use the final pressure to calcualte
    • wirr=-P2(Vfinal-Vinitial)
  70. When is work maximized?
    When a process is reversible.
  71. What happens to internal energy for an isochoric process?
    It is only a function of change of heat as volume is 'fixed'
  72. Isochoric
    Constant volume
  73. What is Enthalpy (H)?
    • Enthalpy is a state function equal to :
    • H= U + PV = internal energy + PRessure * Volume
    • This deffinition is only valid if all work is PV work.
  74. What is the change in heat (q)for a constant pressure system?
    incImage Upload 21
  75. Endothermic process definition
    • One in which q and w are positive.
    • This implies that heat and work flow into system.
    • This also implies that the surroundings will lose heat and feel colder.
  76. Exothermic Process
    One in which q and w are negative.This implies that heat and work flow out of the system. This also implies that the surroundings will gain heat and feel hotter in temperature.
  77. What are the two forms of heat capacity and why do we have them?
    • Isochoric: Constant Volume
    • Isobaric: Constant Pressure

    Heat capacity is not a state function. It fluctuates fased on sate functions and as suc hwe need to account for environmental conditions.
  78. What should we know about Cv and what is its formula?
    • This is isochoric heat capacity. It implies that there is a constant volume in system. In general, it is less like lab work/real systems.
    • Due to the lack of change in volume, we asusme this to be purely a function of intenral energy
    • Its formula is: Cv=Image Upload 22
  79. What should we know about CP and what is its formula?
    • This is Isobaric heat capacity. While pressure is constant, volume may vary and we thus may need to account for work. As such it is a function of Enthalpy (H) and is far more common in the lab.
    • Cp = \grImage Upload 23
  80. What is heat capacity?
    How much heat energy (Joules) a kilogram of a substance must absorb to increase by 1 K in temperature.

    It varies with temperature and type of system.
  81. How are Isochoric and Isobaric heat capacity related?
    Cpm =Cvm +R
  82. When can you use either form of heat capacity to find change in heat?
    When working with an ideal gas, either form of heat capacity is equally valid.
  83. What is formula for change in enthalphy?
    iImage Upload 24
  84. What is formula for change in internal energy?
    inImage Upload 25
Card Set
Physical chemistry Test 1
Physical chemistry test 1