chem1a lec 41 spectroscopy

Ethane C${}_2$H${}_6$
Ethylene C${}_2$H${}_4$
Acetylene C${}_2$H${}_2$
UV/V -> valence electron transition ;DNA 200-300[nm]で破壊
iR -> molecular vibration
microwave -> molecular rotation
radio wave -> nuclear spin "juse as electrons do proton (a.k.a. H nucleous) have a spin

chema1 40 molecular orbitals

MO diagram
molecular absorption bands, not lines.  due to nucleus vibrating.
$\sigma_{1S}$ bonding orbital
$\sigma^*_{1S}$ antibonding orbital
Bond order = $\frac{#bonding-electrons - #antibonding-e.}{2}$ > 0 if stable
unpaired electrons ... attracted to magnet O2 Yes(paramagnetic) N2|F2 No(diamagnetic) & "lewis dot structure" cannot predict this.
2p + 2p -> $\sigma_{2P}$ + $\sigma^*_{2P}$ + $\pi_{2P}$ + $\pi^*_{2P}$
pオービタルからパイだけでなくシグマもできる

chem1a 39 light and color

ムーアの法則が半導体産業をモノカルチャーにした

EETimes.com - Counterpoint: Is Moore's Law really the industry's misfortune?
なるほど、ポイントが抑えられている。

chem1a 38 light spectra

electron knock-out:exact & arbitrary P.E. <-> electron excitation within atom:exact
Z${}^2$ n=1 to n=2 in Li${}^{2+}$ (11808(1312x9)-2952(328x9)) kJ/mol  H (1312-328)kJ/mol

chem1a 37 atomic orbitals

chem1a 36 periodic table

"electron configuration notation"
Ex. Be ... [He]2s${}^2$   Mg ... [Ne]3s${}^2$
"effective nuclear charge" trend <-> Ionization Energy trend

chem1a 35

$\Sigma$(ejected e${}^-$) /(atom|mol) = Energy injected /(atom|mol)

5 11 1 36 review

"cofactor" catalyst helper
electrolytic <-> galvanic

Lec 36 | MIT 5.111 Principles of Chemical Science, Fall 2005

5 11 1 35 catalyst

catalyst 'stabilize' or lower transition state (activated complex)
affects rate, but no change in thermodynamics
inhibitor <-> catalyst
heterogeneous ex. metal solid works as catalyst for a gass
reactants@chemistry -> substrates@biochemistry
'active site' ES complex product P
! dynamics <-> kinetics
Michaelis–Menten K${}_M$をv${}_{max}$とその半分を与える濃度から実験的に求めることができる(wikipedia)
peptide bond cleaved protease

Lec 35 | MIT 5.111 Principles of Chemical Science, Fall 2005

5 11 1 34

Plot $\ln$ 'k' - inverse Temperature ... intercept 'A' the facor A| pre-exponential factor
slope ... Energy of activation / R "reaction coordinate" diagram Potential Energy-Reaction Coordinates
Big Activation Energy -> more sensitive to temperature change
$\Delta$H = $\Delta$E + $\Delta$(PV) (1-2% for gas 0% for solid,liquid)
if 1st step in 2 step RxN is exothermic, raising temperature might slow the overall reaction.

Lec 34 | MIT 5.111 Principles of Chemical Science, Fall 2005

UCB chem1a lec 34 all aglow: light energy

bolic acid B(OH)${}_3$ "roach prufe"
light different wavelength <-> momentum different mass balling ball pachinko ball
1 eV = 1240 nm = 242  THz

5 11 1 33 Reaction Mechanism

k${}_{observed}$ k - [reactants] relationship k - [products] relationship
 -> come up with appropriate mechanism to fit the experimental relationships
[NO]${}^2$ [O${}^2$]

step 1. NO + NO ⇔ N${}_2$O${}_2$ -(k1)-> <-(k-1)-
 rate${}_{forw}$ = k${}_1$[NO]${}^2$ bimolecular
 rate${}_{rev}$ = k${}_{-1}$[N${}^2$O${}^2$] monomolecular
step 2.  O${}_2$ + N${}^2$O${}^2$ -(k2)-> NO${}_2$ + NO${}_2$
 rate = k${}_2$[O${}_2$][N${}^2$O${}^2$]
 (*) overall rate of NO${}_2$ formation = 2 k${}_2$[O${}_2$][N${}^2$O${}^2$]
you need to get rid of intermediate [O${}_2$][N${}^2$O${}^2$]
net formation of [O${}_2$][N${}^2$O${}^2$] = k${}_1$[NO]${}^2$ (formed) - k${}_{-1}$[N${}^2$O${}^2$] (decomposed) - k${}_2$[O${}_2$][N${}^2$O${}^2$] (consumed) = 0 @ equilibrium
[N${}^2$O${}^2$] (k${}_{-1}$ + k${}_2$[O${}_2$]) = k${}_1$[NO]${}^2$
 (*) = 2k${}_1$k${}_2$[NO]${}^2$[O${}_2$] / (k${}_{-1}$ + k${}_2$[O${}_2$]) !!! not consistent
fast first step(also reversible) & slow second step. 'rate determining step'
first step @ quasi-equilibrium during the reaction
[NO][Br${}_2$]

Lec 33 | MIT 5.111 Principles of Chemical Science, Fall 2005

5 11 1 32 kinetics continued & mechanisms

Becquerel = [s^-1]
@equilibrium ... rates of forward RxN and the rates of backward RxN are the same
A + B ⇔ C + D
         -> @ k${}_{1}$[A][B]
         <- @ k${}_{-1}$[C][D]
K = [C] [D] / [A][B]
then @ equilibrium k${}_{1}$ / k${}_{-1}$ = K
"elementary reaction" ... rate law can be written as eq. " the reaction order, the molecularity and the stoichiometric coefficient are the same"
"Molecularity"

Lec 32 | MIT 5.111 Principles of Chemical Science, Fall 2005

UCB chem1a lec 33

cathode reduction acceptor
anode oxidation donner
Zn around Fe pipe ... sacrificial electrode metal

CH${}_4$ + O${}_2$ -> CO${}_2$ + H${}_2$O ... $\Delta$G${}^0$ = -818 kJ/mol
$\Delta$G std. state $\Delta$G = $\Delta$G${}^0$ + RL$\ln$Q $\frac{(1)}{{(1)}^2(1)}$ $\Delta$G = $\Delta$G${}^0$
$\Delta$G equil $\Delta$G = $\Delta$G${}^0$ + RL$\ln$Q = 0

5 11 1 31 kinetics

labile ... high rate
Rates of RxN = f (temperature ,concentration ,catalysts ,nature of material ,mechanism)
Rate Law 'k' rate constant <-> 'K' equilibrium constant
 elementary reactions <-> RxN with mechanisim (steps)
'order' 'half-life'
 

Lec 31 | MIT 5.111 Principles of Chemical Science, Fall 2005

UCB chem1a lec 32

Energy,Enthalpy,Entropy "keeping track of " something invisible

Physical (#chemical) change
 Heat transfer = q =q m C${}_p \Delta$T
 Melting and Vaporize


Chemical bonds
 H:Enthalpy
 H--:Exothemic
 H++:Endothermic (biologist call this "high energy"bond meaning highly reactive)

$\Delta$H
 Bond dissociation - (atoms) , - of formation (elements) #2 reference point

$\Delta$G${}^0$
 $\Delta$G${}^0$ = - R T $\ln$ K
 $\Delta$G${}^0$ = - n F $\Delta$E${}^0_{cell}$
 $\Delta$G${}^0$ = max work  ?P$\Delta$V?

E${}^0$ standard 'reduction' potential

UCB chem1a lec 31 the Sun

plasma ... the 4th states of matters
positron ... positive electron

UCB chem1a lec 30 Batteries

oxidize ... さびる、イオンになる、単体から化合物、-> +∞
reduction ...  戻る。単体になる。-> -∞
$\Delta$G = - n F $\Delta$E ... 'Maximum' work E自体は'n'つまり何価のとりひきかは関係しない。i.e. 端子間電圧を見るときには'n'を見ていない。

5 11 1 30

energy levels are flipped @tetrahedral ligands configuration relative to @octahedral case
High spin system example [Fe(H${}_2$O)${}_6$]${}^{3+}$ ... d${}^5$ system = t${}_{2g}^3$ e${}_g^2$ Crystal Field Splitting Energy = 0 Weak field ligands
Low spin system example [Fe(CN)${}_6$]${}^{3+}$ ... d${}^5$ system Strong Field #Energy Gap > Pairing Energy
"Transition Complex" "cofactor"
paired -> diamagnetic, unpaired -> paramagnetic

Lec 30 | MIT 5.111 Principles of Chemical Science, Fall 2005