Chapter 20 & 21

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  1. 1st law of therm/law of conservation of energy
    energy is neither created nor destroyed; total energy content of the universe is constant
  2. enthalpy change (ΔH)
    the amount of heat (q) absorbed by the system; the enthalpy change for a process is the same whether it occurs in a single step or a series of steps
  3. spontaneous reaction
    on e for which a net change in amount(s) is observed to take place without intervention from outside the system; if under a given set of conditions a reaction is spontaneous, then its reverse is not spontaneous
  4. entropy (S)
    • S = k ln(W)
    • entropy = Boltzmann's constant (in J/Kelvin) x l(W), which are microstates
    • for every process that occurs, the entropy of the universe will increase (ΔSuniv > 0)
  5. microstate (W)
    is each way the particles and energy of our system can be distributed within the given volume, at the temperature given; all give the same measured values of P, V, n, T and E (internal energy)
  6. 2nd law therm dynamics
    • the entropy of the universe increases in a spontaneous process and remains unchanged in an equilibrium process
    • ΔSuniv = ΔSsys + ΔSsurr > 0
  7. ATOMS are the the ones that are oxidized or reduced
    not the entire compound
  8. the COMPOUND is the species that is the agent
    compounds are oxidizing agents and reducing agents
  9. if ΔG is > 0, then the reaction is:
  10. if ΔSuniv is < 0 (or negative), the reaction is:
    not spontaneous, CANNOT occur; however the REVERSE of such a process (because it will be positive) is spontaneous
  11. if ΔSuniv is > 0 (or positive), the reaction is:
    SPONTANEOUS at all temperatures!
  12. if ΔG < 0 (or negative), then the reaction is:
  13. ΔH
    enthalpy change; aka the amount of heat absorbed by the SYSTEM
  14. if ΔSuniv= 0 or ΔG = 0:
    the system is at EQUILIBRIUM, so no net changes are occuring
  15. ΔSuniv= ΔSsys - ΔHsys/T
    entropy of universe = entropy of the system minus enthalpy of the system/Temp
  16. G = free energy
  17. whEN doing redox reactions:
    • if basic, don't forget to add OH- to both sides of the half reaction
    • -when figuring out how many e- to add to each side, make sure to factor in stoichiometry when calculating charges (if a compound has a 2 in front of it, you have to multiply the charge by 2)
Card Set:
Chapter 20 & 21
2011-08-12 01:34:22
Gen Chem II

Final Exam
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