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Definition of oxidation vs reduction
- Oxidation: loss of electrons (increase in oxidation state)
- Reduction: gain of electrons (decrease in oxidation state)
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Galvanic cell vs. Electrolytic cell
- Galvanic cell: produces current from a spontaneous reaction
- Electrolytic cell: consumes current to drive a nonspontaneous reaction
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Typical sketch of Galvanic cell
 - Left 1/2 cell: anode - oxidation (reducing agent)
- Right 1/2 cell: cathode - reduction (oxidizing agent)
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Electrochemical shorthand notation
| indicates salt bridge | | separates phases |
- , separates different ions in the same phase
- Anode on left, cathode on right in order of reaction
- Be sure to include anode/cathode solids
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Electrochemistry Equations
- E°oxidation = -E°reduction
- E°cell = Eox + Ered
- E = E° - (.0592/n)logQ
- ΔG° = -nFE°cell (n= mol e- F = 96485 C/mol e-)
- E = E° - (RT/nF)lnQ (n= mol e- F = 96485 C/mol e-)
- V = J/C
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Types of voltaic cells
- Primary batteries: redox reactions that cannot be easily reversed. Used up reactants = dead battery
- Secondary batteries: rechargeable (use reversable redox reactions)
- Fuel cell: reactants are supplied from external source
- Acidic dry cell: expensive, non reachargeable, heavy, easily corroded
- Lead storage battery: rechargeable, heavy (in cars)
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General Electrolytic cells + info
- Anode: electons drawn from the + terminal of battery
- Cathode: electrons forced toward the - terminal of battery
- Amount of product is related to #electrons transferred (electrons treated as reactants)
- # mol electrons that flow through cell depend on current/length of time (1 amp = 1 c/s, 1 mol e- = 96485 c, 96485c/mol e-)
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Types of nuclear rays/emissions
- α emission: loss of 4/2He (loss of 4 neutrons, 2 protons)
- β emission: loss of 0/-1 β (gain of 1 proton)
- γ emission: loss of 0/0 γ (no change)
- positron emission: loss of 0/1 β (loss of one proton)
- electron capture: gain of 0/-1 e (product side -> loss of 1 proton)
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Kinetics of Radioactive decay
- All are first order
- Rate = kN (N= # radioactive nuclei)
- t1/2 = .693/k
- ln(N1/N0) = -kt = ln(rate1/rate0)
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Half life of C-14
5730 years
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Mass defect and binding energy
- 1 MeV = 1.602x10-13 J
- 1 amu of mass defect = 931.5 MeV
- Mass defect = n(mass proton) + m(mass neutron) - (mass total)
- Binding energy = mass defect/# of nucleons
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