definitions

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rcrchick
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17120
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definitions
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2010-05-01 19:33:45
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last chem exam
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last chem exam
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  1. solution
    • a mixture of substances that have a uniform composition
    • (homogeneous mixture)
  2. solvent
    the dissolving medium of a solution normally present in the greater amount
  3. solute
    • a substance that is dissolved in a solvent, to form a solution.
    • normally present in the lesser amount
  4. saturated solution
    • a solution in which undissolved solute is in equilibrium with dissolved solute
    • *you cannot dissolve any more solute*
  5. unsaturated solution
    a solution in which more solute can be dissolved in the solvent
  6. solubility
    the amount of substance that dissolves in a given amount of solvent at a specified temperature
  7. miscible
    liquids that mix in all proportions.
  8. a momogeneous mixture is an example of what?
    a solution
  9. ethanol and water is an example of what?
    miscible
  10. immiscible
    liquids that do not mix
  11. oil and water is an example of what?
    immiscible
  12. (solubility factors)
    solid in a liquid:
    if temperature goes up...
    then solubility goes up
  13. (solubility factors)
    solid in a liquid:
    if pressure goes up...
    then there is no effect on solubility
  14. (solubility factors)
    gas in a liquid:
    if temperature goes up.....
    then solubility goes down
  15. (solubility factors)
    gas in a liquid:
    if pressure goes up....
    the solubility goes up
  16. (calculations)
    mass %
    • gram solute
    • ---------------------------------------------- x 100
    • (grams of solute + grams of solvent)

    or

    • g solute
    • --------------x100
    • g solution
  17. (calculations)
    PPM (parts per million)
    • g solute
    • -----------------------------x1,000,000
    • (g solute + g solvent)

    or

    Mg/L
  18. (calculations)
    volume %
    • volume of liquid
    • --------------------------------x100
    • total volume of solution
  19. (calculations)
    molarity
    • moles
    • -------=M.
    • Liters
  20. what are dilution problems?
    • those in which you are asked to calculate a solution concentration from a more concentrated starting point
    • M1V1=M2V2
  21. what is colligative properties?
    properties in which the total number of solute particles present matter more thatn their physical properties
  22. what is an acid?
    a solution gennerally concidered as H+ ions
  23. what is a base?
    a solution generally considered as OH- ions
  24. what is a salt?
    ionic compounds of cations and anion; generally far left and far right of combinations
  25. what is the definition of electrolytes?
    • a substance that undergoes partial or complete dissociation in solution.
    • in doing so, the solution will conduct electricity
  26. what are electrolytes?
    all acids, bases and salts
  27. what are non-electrolytes?
    they will not dissociate in solution to conduct electricity
  28. what is sugar water (sucrose) and example of?
    a non-electrolyte
  29. strong electrolytes will what...
    completely dissociate
  30. weak electrolytes will what....
    partially dissociate
  31. what does a single -> mean?
    strong electrolyte
  32. what does a double <=> mean?
    weak electrolyte
  33. NaOH(aq)->Na+OH
    is this a strong or weak electrolyte?
    strong
  34. HC2H3O2(aq)<=>H+C2H3O2
    is this a strong or weak electrolyte?
    weak
  35. (pH/pOH)
    on a pH scale what is 0,7,14?
    • 0-acidic
    • 7-neutral
    • 14-basic or alkaline
  36. (pH/pOH)
    how do you calculate the [H+] from the pH?
    - [H+] 2nd log
  37. (pH/pOH)
    how do you calculate the pH from the pOH?
    pOH-14=
  38. (pH/pOH)
    how do you find the [OH-] from the pOH?
    -pOH 2nd log
  39. (pH/pOH)
    how do you find the [OH-] from the pH?
    • first you have to find the pOH by:
    • pH-14=pOH
    • then from the use the pOH to find the [OH-] :
    • -pOH 2nd log= [OH-]
  40. (pH/pOH)
    how do you find the pH from the [H+]?
    ex:[H+]=2.5x10-3M
    2.5 EE 3 - = log= - pH (dont forget that the answer will be negative on the calculator but its not!)
  41. (pH/pOH)
    how do you find the sig figs?
    how ever many #s are in the [H+] or the [OH-] is how many decimal places there are for the pH or pOH

    • ex:
    • [H+]=2.5x10-3M (two sigfigs)
    • pH=2.60 (means two #s after the decimal)
    • pOH=11.40 (two #s after the decimal)
    • [OH-]=4.0x10-12M (means two sigfigs)
  42. what are titrations?
    • very common technique in which the conventration of an unknown substance is determined
    • key: moles of H+=moles of OH-
    • end point is neutralization
  43. (net ionic equations)
    what are the 3 steps of net ionic equations?
    • 1.un-ionized equation
    • 2.total ionic equation
    • 3.net ionic equation
  44. (net ionic equations)
    what is a un-ionized equation?
    everything is written as normal
  45. (net ionic equations)
    what is a total ionic equation?
    equation where substances are written in their most prodominant form when dissolved in H2O
  46. (net ionic equations)
    what is a net ionic equation?
    where only substances that have changed are written down
  47. (net ionic equations)
    what are spectator ions?
    ions that do not participate in the reaction
  48. what is LeChteliers principle?
    if a stress is applied to a system at equilibrium, the system will shift to offset the stress and stablish a new equilibrium
  49. concentration stress:
    A+B<=>C+D

    given the stress what is the equilibrium shift?
    stress:
    1.add A
    2.add B
    3.add C or add D
    4.remove A
    5.remove D
    6.add A and add D
    • 1.to the right
    • 2.to the right
    • 3.to the left
    • 4.to the left
    • 5.to the right
    • 6.unknown without measurements
  50. when is the only time volume stress rule applies?
    and what is the rule?
    • if one of the substances is a gas
    • then the rule is : decreasing the volume of a container will shift the equilibrium to the side with the fewest # of moles of gas
  51. (volume stress)
    N2(g)+3H2(g)<=>2NH3(g)
    remember:
    4 moles to 2 moles
    if volume stress is up the it shifts where?
    to the left
  52. (volume stress)
    N2(g)+3H2(g)<=>2NH3(g)
    remember:
    4 moles to 2 moles
    if volume stress is down then it shifts where?
    to the right
  53. (volume stress)
    N2(g)+O2(g)<=>NO2(g)
    remember:
    2 moles to 2 moles
    if volume stress is down the it shifts where?
    no shift
  54. (temperature stress)
    what is exothermic?
    heat is emitted
  55. (temperature stress)
    what is endothermic?
    heat is abdorbed
  56. (temperature stress)
    is this exo or endo?
    H2(g)+Cl2(g)<=>2HCl(g)+185KJ
    exothermic
  57. (temperature stress)
    is this exo or endo?
    H2(g)+I2(g)+51.9KJ<=>2HI(g)
    endothermic
  58. (temperature stress)
    if the temp stress is up then what is the shift?
    H2(g)+I2(g)+51.9KJ<=>2HI(g)
    to the right
  59. (temperature stress)
    if the temp stress is down then what is the shift?
    H2(g)+I2(g)+51.9KJ<=>2HI(g)
    to the left
  60. (temperature stress)
    if temp stress is up then what is the shift?
    H2(g)+Cl2(g)<=>2HCl(g)+185KJ
    to the left
  61. (temperature stress)
    if temp stress is down then what is the shift?
    H2(g)+Cl2(g)<=>2HCl(g)+185KJ
    to the right
  62. what is a catalyst?
    • a substance that affects the rate of a reaction
    • *not its chemical equilibrium*
  63. (Quantitative)
    jA+kB<=>pRqS

    what are A,B,R,S?
    the substances
  64. (Quantitative)
    jA+kB<=>pRqS
    what are j,k,p,q?
    • balanced rxn
    • coefficients
  65. (Quantitative)
    what is KE or KC?
    equilibrium constant
  66. (Quantitative)
    what is KE?
    • products (concentration of)
    • --------------------------------
    • reactanct(concentration of)

    =look at notes

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