chemmmm eq

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alazeidan
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181976
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chemmmm eq
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2012-11-06 21:53:34
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chem
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  1. closed system
    • a system that may exchange energy but not matter with its surroundings 
    • when chemical changes are studied it is easier when the system is seperated from its surroundings (definate physical boundry)
  2. dynamic equilibrium
    a balance between forward and reverse process occuring at the same time (opposing changes must be occuring at equal rates)
  3. forward reaction
    in an equilibrium equation the left to right reaction
  4. reverse reaction 
    in an equilibrium equation the right to left reaction
  5. solubility equilibrium
    a dynamic equilibrium between a solute and a solvent in a satruated solution in a closed system
  6. satruated solution
    A saturated solution is a solution in which the maximum amount of solute has been dissolved.
  7. phase equilibrium
    a dynamic equilibrium between different physical states of a pure substance in a closed system
  8. chemical reaction equilibrium
    a dynamic equilibruim between reactants and products of a chemical reaction in a closed system 
  9. solubility equilibrium ...
    if solution is in a closed system then the observable properties of the solution become constant 
  10. dissolution 
    process of dissolving 
  11. kinetic molecular theory and solubility eq
    particles are always moving and collisions are occuring even if no changes are observed 
  12. solubility step one 
    when solute is first added many more ions dissociate from the crystal than crystalize into it 
  13. solubility step 2 
    as more ions come into the solution more ions also crystalize 
  14. solubility step three
    at solubility eq solute ions dissolve and crystalize at the same rate (no observable changes occur in concentration ions. quantity of solid present)
  15. phase eq --> evaporation / condensation eq
    • in a closed system evaporation occurs when molecules collide and gain energy to start a second phase (gas state)
    • condensation occurs when number of gas molecules increase and collde with the surface of liquid and lose energy become liquid 
    • as time pases the rate of evaporation and condensation become equal (phases occur but no change is observed)
    • pressure in gas phase remains the same
  16. the tendency of any liqid to evaporate inreases at 
    higher temperature therefore concentration and pressure of gas increases if eq is reached at a higher temp
  17. phase eq can occur in
    open systems
  18. solid / liquid phase eq
    • reached at melting and boiling point
    • if ice was placecd in warm water (ice melts fasternthatn water freezing therefore melgint =net change
    • as the temp of water decreases the rate of melting dec and the rate of freeing inc until temp is 0 deg then rates become equal )
  19. chemical reaction eq
  20. quantatative reaction
    • a reactio in which virtually all of the limiting reagent is consumeed (in open system no eq)
    • only occur in closed systems
  21. final syate of hemical system at eq can be explained as
    a competition bw collisons of reactants to form products or products to form reactants 
  22. reversable reaction
    a reaction that can achieve eq in the forward or reverse direction
  23. overall system compostition the esame eq concentratons are reached 
    whether eq is approached in the forward or reverse 
  24. percent reaction at chemical eq
    • the tield of product measured at eq compared with the maximum possible tield of product 
    •  
  25. formula for perent reation 
    percent reation =actual product yield / theoretical produt yield x100%
  26. pr =1% or less
    reactions that favor reactants very strongly (mixing reactants have no obervable result)
  27. pr ==99% or more 
    reactions that favor products very strongly (observed as complete or quantatative written with single arrow)
  28. pr < 50 
    reactants are fav with noticeable eq conditions
  29. pr.50 
    products are fav with noticeable eq conditions
  30. the eq constant k 
    the value obtained by the mathematical combination of eq oncentrations using the eq law expression
  31. eq constant equation
  32. ABCD
    chemical entities in gas or aq phase 
  33. abcd
    coefficients from balanced eqation
  34. characteristics
    • products are written in the numerator
    • reactants are written in the denominator
    • coefficients of balanced eqation=exponents
    • concentrations in eq law expression =molar concentrations of entities at eq
  35. Vf 
    forward reaction
  36. Vr
    reverse reaction
  37. Kf
    • rate constant for Vf 
    • Vf=Kf [A][B]
  38. Kr
    • rate constant for Vr
    • Vr=Kr[C][D]
  39. at eq rate constant of r and f are
    • equal 
    • Vf=Vr
  40. K varies with 
    temperature
  41. limitations of eq constants and percent reaction values
    the position of eq is a measure of the extent to which reactants become products in a closed system 
  42. percent reaction depends on 
    temp and concentrations
  43. heterogeneous eq
    eq in which reactants and products are in more than one phase
  44. homogeneous eq
    ew in which all entities are in the same phase
  45. the magnitude of K
    provides a measure of the extent to which the raction has gone to completion when eq is reached
  46. k>>1
    the reaction proceeds to completion the concentrations of products are much greater tht the concentrations of reactants at eq
  47. k=1
    the concentration of reactants and products are approximately equal to eq
  48. K<<1
    • very small amounts of products formed
    • the concentrations of reactants are much greater that the concentrations of products at eq
  49. le chateliers principle
    • when a chemical system at eq is disturbed by a change in a property the systed adjusts in a way that opposes the change
    • includes : 
    • initail eq state
    • shifting non eq state
    • new eq state
  50. if more of a reactant is added to a system at eq
    • that system will undergo a eq shift
    • reactant concentration decreases
    • some of added reactant changes to products
    • new eq state is formed 
    • shift fwd (right)
  51. removing a product from a system at eq
    • concentration of products increase
    • the reactants decrease untill a new eq is stablished
    • eq shift forward 
  52. when the system shifts
    the initail k value and final k value remain the same
  53. when a reactant is added
    with more reactant particles present per volume collisions are suddenly much more requent for the forwards reaction 

    increase in reactant = forward reacton increse in products

    • as concentration of product increases so does the recerse reaction rate
    • as reactant is consumed forward reaction rate decreases 
    • continue until the 2 rates become equal to eachother
  54. new eq states are
    facster thatn the origninal because the system containses a larger number of particles (more collisions) in dynamic eq
  55. when substance is removes there are
    • less particles pre volume ollisions are less frequent causing dwd reverse reaction
    • decrease reactant =reverse reaction 
  56. le chatelier principle and temperature changes
    energy in chem eq can be treated as reactant / product
  57. endothermic
    reactants+energy <> products
  58. enxothermic reactions 
    reactants<> products + energy
  59. if heat is removed
    eq shifts in the direction that produces heat
  60. if heat is added 
    eq shifts in the direction that absorbs heat
  61. le chatelier principle and gas volume changes
    • the system will react in a wat that resists the change
    • liquids or solids not affected
    • equal # of gas molecules oneach sde are not affected
  62. increase in volume/decrease in pressure
    shifts towards the side with the larger total amount of gaseous entities
  63. decrease volume icrease in pressure
    shifts towards the side with thte smalller total amount of gaseous entities
  64. variables that dont affect chemical eq
    catalyst

    inert gases
  65. inert gas
    noble gas or non reactive gas 
  66. the reaction quotient 
    a test calculation using measured concentration values of a system in the equilibrium expression
  67. q=k
    system at eq
  68. q>k
    system shifts left (product reactant ratio too high)
  69. Q<K
    system shifts right (product reactant ratio is low)
  70. solubility product
    excess solute is in eq with its aq solution
  71. solubility product is established by
    with excess salt and issolvint it until solution is aturated and excess solute remains

    mimxing solutions of two sals
  72. solubility
    the concentration of a saturated solution of a solute in a particular solvent at a partifuclar tempertaure (specific maximum concentration)
  73. solubility product constant
    ksp is the value obtained from the eq law applied to saturated solution
  74. trial ion product
    the reaction quotent applied to the ion concentrations of a slightly soluble salt
  75. predict whether a precipitate forms
    ksp and q values are compared 
  76. ksp
    ion product of a saturated solution in which dissolved and undissolved solutes are in dynamic eq
  77. the dynamic eq that exists between dissolved ions and any undissolved solute ensure that there will be no net crystalization
    • solution is unsatruated
    • not capable of dissolving more ions 
    • will not form a precipitate
  78. trial ion product > ksp
    more ions in solution than necessary for solution = super saturated solution (solute concentration exceeds the eq concentration)
  79. ion product Q>ksp
    super saturated precipitate will form
  80. ion product q= ksp 
    saturated precipitate will not form
  81. ion product q<ksp 
    unsaturated precipitate will not form
  82. the common ion effect
    when eq exists in a solution involving ions it can be shifted by dissolving into the solution that adds a common ion 
  83. common ion effect definition
    a reduction in the solubility of a salt caused by the presence of another salt having a common ion 

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