Term
| President GWB announced the Hydrogen Fuel Initiative (HFI) in ___ |
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Definition
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Term
| Energy Policy Act of 2005: title VII: Spark M. Matsunaga H2 Act... |
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Definition
| authorized $3.2 B for H2 and fuel cell tech. |
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Term
| Advanced Energy Initiative in 2006... |
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Definition
| was passed to accelerate research for renewable technologies |
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Term
The development of hydrogen and fuel cell technologies has been
___ well-supported by the U.S. government. |
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Definition
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Term
Who said, "Yes, my friend, I believe that water will one day serve as our fuel, that the
hydrogen and oxygen which compose it... will supply an inexhaustible source of heat and light... I believe that when the coal mines have been exhausted,
we will both heat and be heated with water. Water is the coal of the future"? |
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Definition
| Jules Verne in The Mysterious Island |
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Term
| Sir William Grove discovered fuel and electrolytic cells in ___ |
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Definition
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Term
| the main fuel cell feature is... |
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Definition
| a possibility to directly convert chemical energy of a fuel to electricity with a possible cogeneration of heat |
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Term
| Hydrogen can reliably be used to store the electrical energy because... |
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Definition
| ...it is a good energy carrier |
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Term
| molecular hydrogen is ___ in nature |
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Definition
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Term
| hydrogen technology needs ___ gov't support to develop |
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Definition
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Term
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Definition
was good but then decreased for 2008-09
now it is recovering |
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Term
| hydrogen technology and infrastructure is in the ___ stage of the development. |
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Definition
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Term
| main feature of fuel cells |
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Definition
1. fundamentally different way of generating electricity from a variety of fuels
2. converts the chemical energy of a fuel to electricity and heat
3. technology is easily scalable (1 W - several MW) |
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Term
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Definition
electrical efficiency: up to 50%
total efficiency (elec. + thermal): up to 80% |
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Term
| electrolytic cells are also called ___ and ___ |
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Definition
electrolysis cells
electrolyzers |
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Term
| main features of electrolytic cells |
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Definition
1. efficiency of making H2 from electricity is near 100%
2. engineering principles of fuel and electrolytic cells are very similar
2. tech. is well-developed |
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Term
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Definition
proton exchange membrane fuel cell
polymer-electrolyte membrane fuel cell |
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Term
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Definition
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Term
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Definition
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Term
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Definition
1. main components are essentially the same
2. cathode and anode positions are switched
3. for PEMEC, the PEM can be a porous ceramic or polymeric diaphragm |
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Term
| PEMEC and PEMFC cathode and anode |
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Definition
PEMFC: H2 goes by the anode
O2 goes by the cathode
PEMEC: H2 goes by the cathode
O2 goes by the anode |
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Term
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Definition
production in the USA is very limited because of high cost
(solid oxide FCs are cheaper) |
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Term
| Fuel cell-powered cell phones... |
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Definition
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Term
| fuel cell-powered chargers... |
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Definition
| are available and affordable |
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Term
| fuel cell-powered cars... |
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Definition
1. can be leased in California
2. use reformers that convert gasoline to H2 for the fuel cell
3. electric-gasoline-fuel cell combo car will be on the market soon |
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Term
| H2 fuel stations for cars... |
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Definition
there are 200 in the world
there are 3 in Pennsylvania
there is 1 at PSU |
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Term
| challenges of FCs and ECs |
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Definition
1. cost of cells is high
2. infrastructure should be developed
3. durability should be improved
4. cost of H2 is high
5. right now, the electricity to power electrolysis comes from fossil fuels |
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Term
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Definition
1. ion conductive membrane
2. electrodes
3. bipolar plates |
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Term
| hydrogen is weird because... |
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Definition
...it does not fit easily into the periodic table
1. it has one valance e- but is not a metal at room temp. like the alkali metals
2. it needs one e- to complete its valence shell like the halogens |
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Term
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Definition
length: m
mass: kg
time: s
current: Ampere
temp.: Kelvin
quantity: mol
luminosity: candela
pressure: Pa = N/m^2
energy: J = N*m
power: W = J/s
potential: V = W/A
charge: C = s*A |
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Term
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Definition
Tcrit: 32.95 K
Pcrit: 12.7 atm = 1287 kPa |
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Term
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Definition
H - hydrogen
H(2)=D - dueterium
H(3)=T - tritium |
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Term
| nuclear fusion of hydrogen makes ___ |
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Definition
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Term
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Definition
1. H2 + CO -> methanol feedstock
2. H2 + non-hydrogenated FAs -> hydrogenated FAs
3. H2 + metal ion -> metals
4. H2 + N2 -> NH3 (fertilizer + plastics)
5. -> rocket fuel + fuel cells |
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Term
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Definition
relatively low for H2, but atomic hydrogen is very reactive
need a catalyst split H2 to 2 H |
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Term
| molecular compounds of hydrogen |
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Definition
| can be e- precise, e- rich, or e- poor |
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Term
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Definition
| nonconducting, crystalline solids |
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Term
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Definition
| nonstoichiometric, electrically conducting solids |
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Term
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Definition
| all valence e- of the central atom are engaged in bonds |
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Term
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Definition
| there are more e- pairs on the central atom than are used in bonds |
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Term
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Definition
| there are too few e- to write a proper Lewis diagram for the molecule |
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Term
Reactivity of a hydrogen compound
depends on... |
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Definition
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Term
| s-block hydrogen compounds are ___ |
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Definition
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Term
| d- and f-block hydrogen compounds are ___ |
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Definition
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Term
| p-block hydrogen compounds... |
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Definition
| vary in their properties and stability |
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Term
| properties of water are... |
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Definition
| useful in the understanding of hydrogen technologies, fuel cells, and electrolytic systems |
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Term
| hydrogen economy is to be developed, the following components are needed: |
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Definition
production, delivery, use, storage, education, codes
and standards, safety, technical validation, fuel cell vehicles |
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Term
| In this class, use 273.15 K (all five digits) |
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Definition
| also answers should have 4 sigdigs |
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Term
| the historic trend of hydrocarbon fuel use suggests... |
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Definition
...that we progressively
move towards fuels with lower carbon content |
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Term
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Definition
1. made of two electrodes connected by an electrolyte
2. usually oxidation is placed on the left and reduction on the right, for clockwise e- flow |
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Term
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Definition
an electrode and its electrolyte
(two electrodes may share the same compartment) |
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Term
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Definition
1. a tube containing a concentrated electrolyte solution that completes the electrical circuit
2. used when the two electrolytes are different; it links the two electrode compartments |
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Term
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Definition
| electrochemical cell that uses a spontaneous chemical rxn to produce electricity |
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Term
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Definition
| electrochemical cell that uses electricity to drive a non-spontaneous chemical rxn |
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Term
| redox and cathode & anode |
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Definition
cathode- reduction takes place
anode- oxidation takes place
AOIL-CRIG |
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Term
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Definition
galvanic cell: cathode is + and anode is -
electrolytic cell: cathode is - and anode is + |
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Term
| IUPAC rules for constructing electrochemical diagrams |
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Definition
| Cu(s)|Zn(s)|ZnSO4(aq)||CuSO4(aq)|Cu(s) |
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Term
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Definition
Cu(s)|Zn(s)|ZnSO4(aq)||CuSO4(aq)|Cu(s)
total rxn = (right half rxn)-(left half rxn)
left: Zn2+(aq) + 2e- = Zn(s)
right: Cu2+(aq) + 2e- = Cu(s)
total: Cu2+(aq) + Zn(s) = Cu(s) + Zn2+(aq) |
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Term
| cell potential difference |
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Definition
Cu(s)|Zn(s)|ZnSO4(aq)||CuSO4(aq)|Cu(s)
total pot. dif. = (right pot.)-(left pot.)
left: Zn2+(aq) + 2e- = Zn(s) -> -0.76
right: Cu2+(aq) + 2e- = Cu(s) -> 0.34
total pot. dif. = 0.34 - -0.76 = 1.10 V |
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Term
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Definition
positive pot. dif. means oxidation takes place (anode) on the left and reduction (cathode) on the right
negative pot. dif. means the opposite |
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Term
| writing half rxns: on what side do you put e-? |
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Definition
for red: always put e- on the left side
for ox: always put e- on the right side |
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Term
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Definition
Zn and Cu electrodes
electrodes are separated so that ZnSO4 and CuSO4 don't mix
the electrode compartments are joined by a salt bridge, which usually has KCl |
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Term
| KCl is usually used in the Daniell cell salt bridge because... |
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Definition
| ...because K+ and Cl- conduct electricity almost equally -> symmetry -> no accumulation of liquid junction potential (potential at ends of salt bridge) |
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Term
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Definition
E = Eo - (RT/vF)lnQ
ex, E = Eo - (RT/2F)ln(aCuaZn2+/aZnaCu2+) |
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Term
| it's impossible to measure the potential of a single electrode, so... |
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Definition
| ...we define an electrode as zero, the standard hydrogen electrode (SHE), and measure potentials relative to that |
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Term
| how to measure potentials using a SHE |
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Definition
put the SHE on the left and the electrode you want to measure on the right
measure the potential
then use Eo = ΔrGo/(vF)
where ΔrGo = (ΣprodviΔfGio) - (ΣreacviΔfGio)
*be careful using this method at elevated temps! |
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Term
| Electrochemical Series CRC Handbook 89.pdf |
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Definition
3 tables listing standard reduction potentials, E° values, at STP
-Table 1: alphabetical list of the elements, according to symbol
-Table 2: list of reduction rxns that have (+) E° values, in increasing order
-Table 3: list of reduction rxns that have (-) E° values, in increasingly negative order |
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Term
| Standard Thermo Properties of Chemical Substances CRC Handbook 89.pdf |
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Definition
This table gives the standard state chemical thermo properties of ~2500 substances in the crystal, liquid, and gas states
the properties listed are DELTAHfo, DELTAfGo, So, and Cp |
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Term
| Thermo Properties of Aq Systems CRC Handbook 89.pdf |
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Definition
This table contains standard state thermo properties of ions and neutral species in aq. solution
It includes enthalpy and Gibbs energy of formation, entropy, and heat capacity
order: cations, anions, neutral species |
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Term
| Thermo Properties as a Function of Temp CRC Handbook 89.pdf |
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Definition
| The thermodynamic properties Cp°(T), S°(T), H°(T)-H°(Tr), -[G°(T)-H°(Tr)]/T and formation properties Δf H°(T), ΔfG°(T), log Kf°(T) are tabulated as functions of temp from 298.15 to 1500 K for 80 substances in the standard state |
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Term
Ex. Calculate potential diff. of a galvanic cell at STP
method 1 |
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Definition
Cu(s)|Zn(s)|ZnSO4(aq)||CuSO4(aq)|Cu(s)
rxn = (right rxn) - (left rxn)
Eo = (Cu2+ + 2e- -Cu(s)) - (Zn2+ + 2e- -Zn(s))
Eo = 0.34 - -0.76 -> 1.10 V
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Term
Ex. Calculate potential diff. of a galvanic cell at STP
method 2 |
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Definition
Cu(s)|Zn(s)|ZnSO4(aq)||CuSO4(aq)|Cu(s)
rxn = (right rxn) - (left rxn)
ΔrGo = Cu2+ + Zn(s) - Cu(s) - Zn2+
ΔrGo = ΔfGoCu2+ + ΔfGoZn(s) - ΔfGoCu(s) - ΔfGoZn2+
ΔrGo = -147.1 + 0 – 65.5 – 0 -> -212.6 kJ/mol
Eo = -ΔrGo/(vF) = -(-212.6k)-/(2*96485)
Eo = 1.10 V |
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Term
| pressure dependence of Eo... |
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Definition
| is defined by the volume of the rxn* |
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Term
| temperature dependence of Eo... |
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Definition
| is defined by the entropy of the rxn* |
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Term
| calculating DELTArGo at elevated T and P |
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Definition
4 options:
1. Use the Gibbs energy of formation that are already calculated at elevated temperatures (CRC tables) and use Eo = -DELAtrGo/(vF)
2. if >150 C, use most accurate eqn
3. if <150 C, use approx. eqn
4. if <75 C, use most approx. eqn (see slide 5.7) |
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Term
| the background of the equilibrium electrochemistry is ___ |
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Definition
| thermodynamics ((chemical equilibrium and solution thermodynamics) |
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Term
| to calculate potential difference of an electrochemical cell, you need ___ and ___ |
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Definition
standard electrode potentials
activities (activity coeffs and concentrations) |
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Term
| to calculate the standard electrode potentials at elevated T or P... |
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Definition
| additional thermodynamic properties are needed |
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Term
| are higher T and P good for fuel cells? |
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Definition
higher T is good as long as the material isn't compromised
higher P is good, but it costs too much (usually use 5 atm, max)
*but for electrolyzers, P about 20 atm is ok because you would pressurize the H2 anyway |
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Term
| what is the meaning of the activity coeff? |
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Definition
| shows how far you deviate from ideal concentration |
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Term
| for a pure substance, activity is always ___ |
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Definition
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Term
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Definition
| a = (conc.)/(standard conc.)*(activity coeff) |
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Term
| If the anode (red.) is on the left and the cathode (ox.) is on the right, electron flow is ___ |
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Definition
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Term
| exchange current density is defined as... |
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Definition
| the rate where the anodic and cathodic rates are equal |
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Term
| typical value for alpha (transfer coeff.) is ___ |
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Definition
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Term
| a large exchange current density (fast rxn) is ___ |
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Definition
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Term
| as io increases, reversibility ___ |
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Definition
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Term
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Definition
| the symmetry of the barrier to the rxn |
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Term
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Definition
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Term
| 3-electrode electrochem. cell is used to... |
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Definition
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Term
3-electrode electrochem. cell terms
counter electrode
working electrode
reference electrode |
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Definition
counter- the electrode together with the working electrode
working- the electrode you want to study
reference- the electrode in the test tube thing |
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Term
| concentration polarization is aka ___ |
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Definition
| concentration overpotential |
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