Fundamentals of Electrochemistry CHEM*7234 / CHEM 720 Lecture 4 INSTRUMENTATION.
Lecture of 19 February 2020 - California Institute of ... · Lecture of 19 February 2020 Outline of...
Transcript of Lecture of 19 February 2020 - California Institute of ... · Lecture of 19 February 2020 Outline of...
Lecture of 19 February 2020Outline of today's lecture
Midterm exam - average = 71•Electrochemistry and oxidation-reduction equilibria•
Midterm Exam discussion
problem 7 charge balanceKt t C A 0
ret Ai O I ly
C kaCA xa
Ht KaC 0.3M Kai 1 8 0 4
CA 1 0 1M
htt 3.6 0 414 pH 3 45
problem 7 O 05M malonic acidO l M Naz Melchett
calculate the pHNat t HH CO A t 2CA
Cpa 0.1514 Carat O 2Ml
Nat A x 2 CA
0.2M CTtacCIHt tka.CI tkaTka A
CtkaiKa AtHt t ka Itt c Kaikaz
htt 404 0 6 M pLt 5.39
problem 13 Hasoy Hsoj Ht Kaos
HSE Isaf DHT KaHo
2
problem 14 Ksp ApbaAsap
2E S2 go28
In O M e I 78 f 26 0414
in 0.01M I I 6265S 2.01 0 414
TKsplot
Z
Oxidation Reduction Equilibriaenergy of a charged species depends on OIelectrical electrostatic potential v
related to work required to bring G chargefrom
infinity to potentialOI with 1 J 7 C x 7 V
n moles of electrons throughpotentialdifference0
work ng Na o of Jchange potentce drop
of 1.602 10 19 C single Ct charge1 C G 24 X 018 changes
Coulombs mole e g Na 96487 C meE Faraday F
current flow 1 Amp I C s I
6 24 10 8charggs I
0 Gee n f DOIw un
B
Respiration Example
basal rate of Ozconsumption I met Oz hi
02 4 e 4 Ht 2 Hz 0
I mol Oz hi 4 mole hi
4F Chr l 100 Amps
power 100 A X IV COO W 100 J s t
104 KJ day I
2500 nutritionalcalories 1 day
4
electron transfer oxidation reduction reaction
involves change in oxidation state number
assigning oxidaton Statesi elements by themselves 20
2 H generally t 1
37 0 generally 24 for wins oxidation state chargeFe Fett festoxidation ferricthan metal
reductionferrous
in general oxidation stats are assigned basedon electronegativities of bonded atoms
bonding to a more electroneg atom_oxidations
bondingto a less electroneg atom reduction
CHL Cµ
OIC O
c HY co HY o cut ofmore reduced C more oxidized C
formal oxidation state 5
Oxidation loss of electronsreduction gain of electrons
balancing oxidation reduction reactions
assign oxidation States
Cpus tguys of t.fi Npg
Zt 2 b t a It 6 2 2 2
Gtoxidation Cris SOY a Instance
5T 2Treduction NOI NO reduction
half reacts
balance egs wrt atoms being redufqdiaffeybalance Wrt electrons
ccu s soy ta t 8e
N05 3e NO
6
balance 0 by adding H2O
a St 4h20 Cu t Sai Se
Ng 3e NO t 2H2O
balance Lt by adding Itt
Cust 4H2O Cult 5042 85 8 Ht
Nos t 3 e t 4 Itt NO t 2420
multiply each reaction to get samenumber of electrons and add
3 Cus 8N05 8Ht 3 Cu't x 3Soy8 Not 4h20
Voila the equation is balanced