CH7 Unit 4

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  1. the study of energy, work and heat
  2. the law of ___ help us to understand why some chemical reactions occur and others do not
  3. contains the process under study
  4. the rest of the universe
  5. ___ ___ for energy stored in a chemical system cannot be measured
    absolute value
  6. can measure the ___ ___ ___ during these chemical changes
    change in energy
  7. breaking of bonds means?
    add energy
  8. forming bonds means?
    give off energy
  9. first law of thermodynamics?
    energy of the universe is constant
  10. AB + CD ->?
    AD + CB
  11. if a reaction will occur?
    • bonds must break
    • breaking bonds requires energy
  12. energy is a product in this reaction
    exothermic reaction
  13. +in an exothermic reaction ( AB +CD-> AD + CB) what happens to the reactants? what happens to the products?
    • the bonds must be broken, requiring energy
    • the bonds are formed, releasing energy
  14. requires energy
  15. in an exothermic reaction, where is the heat?
    in the product
  16. in an endothermic reaction, where is the heat?
    in the reactants
  17. represents heat energy
  18. what reduces activation energy?
  19. is exothermic negative or positive?
    negative delta H
  20. is endothermic negative or positive?
    positive delta H
  21. energy released, enthalpy is?
  22. energy absorbed, enthalpy is?
  23. sign for enthalpy?
    delta H
  24. add energy to make it go from A to B in a reaction
    endothermic (+delta H)
  25. occurs without an external energy input
    spontaneous reaction
  26. most exothermic reactions are?
  27. what is used to help predict is a reaction will occur?
  28. gibbs free energy equation?
    delta G = delta H - delta S (entropy)
  29. measure of disorder
    entropy( delta s)
  30. a measure of the randomness of a chemical system
  31. the universe spontaneously tends toward increasing disorder or randomness
    the second law of thermodynamics
  32. highly disordered system, the absence of a regular, repeating pattern
    high entropy
  33. well organized system such as a crystalline structure
    low entropy
  34. there is not such thing as negative
  35. entropy reaction formula?
    delta S = S(products) - S (reactants)
  36. a positive entropy means?
    an increase in disorder for the reaction
  37. a negative entropy means?
    • a decrease in disorder for the reaction
    • (goes toward more order)
  38. processes having positive entropy?
    • melting
    • vaporization
    • dissolution
  39. represents the combined contribution of the enthalpy and entropy values for a chemical reaction
    free energy (delta G)
  40. what does free energy predict?
    spontaneity of chemical reactions
  41. negative free energy?
    always spontaneous
  42. positive free energy?
    never spontaneous
  43. if exothermic and positive entropy?
  44. if endothermic and negative entropy?
  45. need to know both ___ and ___ to predict the sign of free energy
    • enthalpy
    • entropy
  46. ___ also may determine direction of spontaneity
  47. the measurement of heat energy changes in a chemical reaction
  48. device which measures heat changes in calories
  49. the change in temperature is used to measure the?
    loss or gain of heat
  50. the number of calories of heat needed to raise the temperature of 1gof the substance 1 degrees C
    specific heat
  51. what do you need to determine heat released or absorbed?
    • specific heat
    • total number of grams of solution
    • temperature change
  52. if heat is absorbed it is ?
  53. heat released?
  54. 1000 cal = __ kcal = __ Cal
    • 1
    • 1
  55. nutritional calorie?
    C (capital c)
  56. used to measure nutritional Calories
    bomb calorimeter
  57. the study of the rate of chemical reactions
  58. determines if a reaction will occur spontaneously, but tells us nothing about the amount of time the reaction will take
  59. represents changes over time
    kinetic information
  60. the rate of ___ ___ can aid in calculating the rate of the chemical reaction
    color change
  61. one that produces product molecules
    effective collision
  62. ___ is required to break bonds
  63. the minimum amount of energy required to initiate a chemical reaction
    activation energy
  64. an extremely unstable, short lived intermediate complex
    activated complex
  65. factors that affect reaction rate?
    • structure
    • shape and orientation
    • concentration
    • temperature
    • physical state
    • presense of a catalyst
  66. ___ charged species react more rapidly
  67. ions with the same charge?
    do not react
  68. magnitude of the activation energy is related to?
    bond strength
  69. rate will generally ____ as concentration ___
    • increase
    • increase
  70. rate ___ as temperature ____
    • increases
    • increases
  71. a higher percentage of these collisions will result in product formation
    higher kinetic energy
  72. a substance that increases the reaction rate
  73. a ___ interacts with the reactants to create an alternative pathway for product production
  74. atoms, ions, compounds are close together but restricted in motion
    solid state
  75. particles are free to move but often are far apart causing collisions to be relatively infrequent
    gaseous state
  76. particles are free to move and are in close proximity
    liquid state
  77. reactions are ____ in the liquid state and ____ in the solid state
    • fastest
    • slowest
  78. in a rate equation, used?
  79. this type of reaction has a double arrow
  80. equilibrium reactions are also called
    incomplete reactions
  81. reversible reactions/
    physical equilibrium
  82. ex of physical equilibrium?
    • sugar dissolved in water
    • dissolved oxygen in lake water
  83. a process that can occur in both directions
    reversible reaction
  84. the rate of the forward process in a reversible reaction is exactly balanced by the rate of the reverse process
    dynamic equilibrium
  85. if you increase the pressure, it drives the equilibrium to side with
    fewer moles
  86. in the dynamic equilibrium, rate forward=
    rate back
  87. never include what in a concentration ?
    solids or liquids
  88. if keq is very large, tan you have?
    lots of products
  89. if keq is very small, then you have?
    lots of reactants
  90. means the equilibrium will be disturbed
  91. if a stress is placed on a system at equilibrium, the system will respond by altering the equilibrium composition in such a way as to minimize the stress
    lechateleir's principle
  92. to relieve stress,?
    remove as much of added material as possible by converting it to reactants
  93. product introduced, equilibrium shifts to?
  94. reactant introduced, equilibrium shifts to?
  95. treat heat as a product
  96. treat heat as a reactant
    endothermic reaction
  97. affects the equilbirum only if one or more substances in the reaction are gases
  98. when pressure goes up, shift to side with?
    less moles of gas
  99. when pressure goes down, shift to side with?
    more moles of gas
  100. has no effect on the equilibrium composition
Card Set:
CH7 Unit 4
2014-04-23 20:58:55
chem 107 chapter unit

energy rate and equilibrium
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