chem 108 exam 3

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chem 108 exam 3
2013-11-03 14:01:57

exam 3
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  1. _________- occurs without outside intervention; goes in the indicated direction. (not related to rate, but may be T dependent)
    spontaneous process
  2. ________________- Law of conservation of energy. (Euniv is constant)
    1st Law of Thermodynamics
  3. H = _______ (related to heat)
  4. change in H = H____- H_____ (is a state function)
    final; initial
  5. change in H < 0 = ______ (usually spont)
  6. change in H > 0 = ______
  7. ____________ - change to system is made in such a way that system can be restored to original state by exactly reversing the change.
    reversible process
  8. ______________- system must take another path to return original state.
    irreversible process
  9. ___ = entropy (measure of disorder)
  10. change is S= S____-S_____
    final; initial
  11. ______________ - in any spontaneous process there is an increase in the entropy of the universe.
    Suniv = Ssystem + Ssurroundings
    2nd Law of Thermodynamics
  12. __________________ - the entropy of a perfect crystal at 0 K is 0.

    T affects magnitude of change in S effect
    3rd Law of Thermodynamics
  13. ___= Gibbs Free Energy (also a state function)

    change is G = change in H- TchangeinS and Change in G= change in Gfinal - Ginitial
    **if change in G < 0, the process is spontaneous

    Change in G = -RT ln K
  14. ___________- study of relationships between electricity and chemical reactions
  15. Oxidation-reduction (redox) reactions:

    ____-loss of electrons
    _____- gain of electrons
    oxidation; reduction
  16. Method of half-reactions:
    1. Identify species being oxidized and reduced and write as half-reactions in the direction given
    2. Balance each half-reaction by first balancing the element undergoing oxidation or reaction, then balance oxygens by adding H2O, then balance hydrogens by adding H, then balance charge by adding e-.
    3. Multiply each balanced half-reaction by a common denominator to balance e- loss and gain 
    4. Add half-reactions back together to obtain balanced equation. Check for smallest coefficients.
    5. If reaction is not in acidic solution, add OH- to each side to neutralize all H+
  17. __________- uses energy from spontaneous redox reaction to generate electricity by transfer of electrons through external pathway
    voltaic (galvanic) cell
  18. ____- electrode where oxidation occurs
  19. _______- electrode where reduction occurs
  20. _________- allows for passage of ions to maintain electrical neutrality
    salt bridge
  21. _______- driving force for electron flow; measured in volts; also called emf or electromotive force
    cell potential
  22. __________________- potential of a half-reaction, written as a reduction, under standard conditions (P = 1 atm, [X] = 1 M), compared to the standard hydrogen electrode.

    E°cell = E°cathode- E°anode
    standard reduction (half-cell) potential (E°red)
  23. If Ecell > 0, this is a
    ________ process and the cell is a voltaic (galvanic) cell.

    ⋅change in G° = -nFE°
    ·n = moles e- changed
    ·F = Faraday's cst = 96,485 C/mole e-
    ·1 C = 1 amp x 1 sec
    note= change in G= -RT ln K, so this is one
    method of determining K
  24. If Ecell < 0, this is a
    ________ process and the cell is an electrolytic cell. Dependence of cell
    potential on concentration is given by the ____ equation:

    E = E° - RT/nF ln Q

    at 25° C, this may be simplified to 

    E= E° - 0.0592V/n log Q

    so one can calculate Ecell if concentrations are known.
    non-spontaneous; Nernst;
  25. At equilibrium, Q = __ and Ecell = _____ V, so this

    E° = 0.0592V/n log K, or 
    log K= nE°/0.0592
    K; 0.00
  26. medical applications of radioactivity:
    1. tracers
    2. cancer treatment
  27. _______= voltaic cell or series of voltaic cells.

    ex. Pb storage battery
  28. *___________- voltaic cell with constant potential bc reactants are constantly added
    fuel cell
  29. ______- naturally occuring oxidation of metals
  30. *___________- forcing a current through a cell to drive a nonspontaneous reaction to occur
  31. *___________ _________- time x current

    1 F = 96,500 C/mole e-
         = 96,500 amp x sec
    quantitative electrolysis
  32. *______- subatomic particles
  33. *_________= protons in nucleus (defines identity of element)
    atomic number
  34. *________- sum of protons and neutrons for a particular nuclide
    mass number
  35. ______- atom with a particular number of neutrons in nucleus
  36. _________- decay of an unstable nucleus by emission of particles and/or electromagnetic radiation. A nucleus which is radioactive is
    called a radionuclide or radioisotope
  37. nuclear equations:

    _______- (α) - 2 4He nucleus

    92238U → 24He + 90234Th
    alpha particle
  38. *________-(β) - electron (e-) 

    90234Th→ - 0e + 91234Pa
    beta particle
  39. *_________- (β+) - positive electron (e+)

    1122Na → +0e
  40. *___________- (γ) - high energy electromagnetic radiation (shorter ray than X-rays)
    gamma radiation
  41. *_______- core electron captured by nucleus 

    80201Hg + -0e → 79201Au+ γ
    electron capture
  42. *__________- neutron/proton ratio; all nuclei with Z>84 are radioactive
    nuclear stability
  43. *__________- conversion of one element into another (decay series)
    nuclear transmutation
  44. *__________- transuranium elements (Z>92)
    manmade elements
  45. _______- radioactivity is 1st order
    ln N/N0 = -kt
  46. *_________- t½ = ln 2/k = 0.693 / k

    isotopic dating - 614C (t½=
    5730 yr)

    detection techniques:
    1. photographic film
    2. Geiger counter
    3. scintillation counter
  47. *_______- E = mc2
    energy relationships
  48. *_________- difference in mass between a nucleus and the sum of its nucleons
    mass defect
  49. *________- energy required to decompose a nucleus into its nucleons
    nuclear binding energy
  50. ______- splitting of heavy 
    92235U + 01n → 56141Ba+ 3692Kr + 301n
  51. ________- reactor types
    nuclear energy
  52. *______- combining of lighter nuclei into heavier nuclei

    11H + 12H → 23He

    note: radioactivity produces ionizing radiation which is harmful to living
    organisms. However, since radioactive isotopes exist for all elements and many
    occur naturally, we are constantly exposed to low levels of radioactivity.
  53. effects of radiation- depends upon:

    1. E of radiation
    2. penetrating ability
    3. ionizing ability
    4. chemical properties of element (biological concentration)
  54. *_______- during lifetime of organism (burns, cancer, etc.)
    somatic effects
  55. *_________- evidenced in later generations (DNA alteration)
    genetic effects