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Unformatted text preview: Note our last homework miniquiz will be next Wednesday — come to class. / GRADE % l) (15 points) You are told the kidney removes drugs from the body by a ﬁrst 0 after the initial administration has a drug concentration of 1.0 X 10'4 M and is
what do you predict will be the concentration after 48 hours? /7{’ anneal I“?
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'1‘“ kg. )5 ‘5 i ‘g w i it? ,p a 0,63%]; 3 i2 ’4 tie. A(g) +B (g) 9 Products i2 31/ g _ 5;, W4 0, no ></2> rde/piocess. If urine tested %__ (113% 104M after 12 hours b) What is the ordéi? of the reaction with respect to [B]? With respect to [A]? Overall rate? fj‘i‘éamﬁé EWWE {Qty caaBasedsonryourwdatanwhichmmechanismnbclaw—Mimi};me 5ft {3‘ m, 3 gm Geodesic“ Ff? {mt}: T53??? WI Mtg 03:
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2) ArtBM—wproducts {Z __ , 913k 2; it? /s. RBempmdastaaeeeﬁ
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{7W 2:” Eizageég MA “332% Do number 3 OR 4. Cross off the one you do not Wish graded. We will grade #4 if no indication is made. 3) The following threepart mechanism is known as the Lindemann Reaction(l923): there is a collision that
produces a very unstable intermediate A* This can convert to products or it could collide with an inert gas
molecule M to lose energy and again become the stable molecule A. k1 I A+A —>A*+A
k2 II A*+M—> A+M
k3 III A* ——>products Assume A* is a highly reactive intermediate and reaches a “steady state.” to a a)(£bpts) Using the steady state approximation ﬁn K O" 3 egg 6, mit‘a’f— klﬁaﬁzym'l * lagfﬁl/ 5'? i1 “‘” ate
0) (Opts) Substitute for [A*] into your formation equation (b). pa moo, @ “JQ L . _ it
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\ 9 WW i». 5 >555)?! g jg.» w a g "If : i 5.» 2,!) ‘ » “‘ is grafﬁti, #3 (5 pts) Evaluate your rate law for the formation of products ( make some comment on the order of the reaction) When the [M] is very large Z W?“ ‘ ...g keg? 5%; = i3“ 5'33: 5W1 E; [VJ/a to:
When the [M] is very small. “2 ‘ M 2..
923 «a to v
7/? ~— orgasm i a on éae’ Comment of youi" results i 5 ,
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lQT at” Law Mi 5 ’ is Fe? 5* it? ﬂew “d a"; {x [Q /’:i {.5 W3 Wed”: We???“ 611% 2:5; gm xjogmégygw 2
WM’ r’ v’ , l, 7.: e (in! 5/!
gig; tiff? mg}? 4931: W 0R 4) The decomposition of ozone in the atmosphere is the subject of many studies.
203 H 302 ,3” z.
Q‘W 2' By experiment the correct rate for this reaction is  1031 = k[03]2[02]" Yes, oxygen has a negative power. dt _ Consider this mechanism k1 I 03 n» 02 + 0 k 2 II 0 + 02 —> 03 k3 III 0. +03 —+ 202 Assume 0 is a highly reactive intermediate and reaches a “steady state.” a) (vim) Using the steady state approximation ﬁnd [0'].
j, ,
d 0 2 o m .  o a, G K = O i’ izé L. (Q?! [Q Eiﬂsl 3
Fe ‘1 e
+ ass» 9! ~  ,2. Q '9}
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b) ( 5pm) Write out the rate law for the change in 03 /
set“; k mg ii 3” “a a, '“ saga}; 3 2:6 ﬁlogl
If you had substituted the correct expression for [0] into the expression for d[03]/dt the resuit is 1 d1;* ﬂggl : 23$an
(11: k2[02]+k3[03] (5 pts) evaluate this expression 2" «a
if k3>>k2 “ wigs: es s 2 [6‘ {65* it
QQY 2 i ” "g a“ W ﬂ as ire;
, “‘2
1fk3<<k2 “dig; .3 H 2h —
q’g‘dmment on your findings. 5) The reaction Aw» products
is thought to be an unusual 3/2 order reaction. a)( gpts)write out the rate for the (reaction of A as suggested
aging
~ s: a a :<
b) (Spts) integrate this rate to create the time concentration equétion. if, __ ﬁg
r “t 2w» 3n Wax? ~ ‘3 A 9 J a w a {ﬁe} \ g 3;. W
(25513;? gala {3 E ‘ M. r J
" g ; VIM ,. ., é; a! “VazA y‘t’s I is, g i a . . 1‘ . . ow, x
c) pts)What graph would you plot to achieive a stralght line for your data? .i ﬁg, f "3 i A; gag?
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W %: Do #6 or #7 Cross of the one you do not want graded. Ifno decision we will grade #7 6) Consider the enzyme catalyzed reaction 13+ S—>ES k1
ES —>E+S k2
ES—>E+P k3 We are given some information about this mechanism.
a) the products E+ P are more stable than the reactants E+ S b) k2<<k1
0) k3 is very smalE
. . . (\\ ,
( pts)based on time informatlon i} WE? $3“ 43"}? f: a it a) What is the rate determining step
3 b) draw the reaction coordinate diagram for the two steps 3 c) give the relative heights of the activation energy for both steps. see sampiegﬁelow. '
1d) locate the intermediate ES 1 j?“ fa ,5 ngje? {\3 1,e identi the activated complexes 2 "if L— aéﬂ’fé <5 .56) F W V a i x ,, mi
sample — ( yours is more complex) ' ' H at}
is"? g < " "s .,.,_..r" ’ 7) I was delighted that one of your classmates used Excel to create a spread sheet for the reaction where I could
. change the values of k1 and k2 for a two step consecutive ﬁrst order reaction. So here is a question thanks to
her. klk2 Here’s the mechanism A —> B ——> C all ﬁrst order, below are several time vs concentration
graphs with different values of k1 and k2 si
on!) Graph 2 Graph 3 If graph 1 is our basis for comparison. a) (5 pts) What can you say about k1 vs k2 in graph 2? Larger, smaller, same? la. iii; its i ' 5L $5 igsiﬁ (its ,
? a u z» _ .. :4 tag Ea ﬁres: b)( Spts) What can you say about k1 vs k2 in graph 3? Larger, smaller, same? balls: ‘3
c. ; < '7 Lent" 5‘ FA r; ”"
L gé [IL/P ﬁght if” gang; {:3 ' , g :WW' g": M: 5‘3 %;g, itseager f9 c) (5pts)for all the graphs what are the values of [A], [B] and [C] at t2 0 and t= oo ? "
as [Al 2: $0139 9&5” w 8) Some short answers ( do any three) (5 pts each) a) nuclear reactions have extreme (huge) activation energies. What can you say about the effect of temperature
on the ﬁrst order nuclear rate constants. Do we have an equation?
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b) give at least two reasons Why every collision between molecules does not produce a product, that is Why is
the “hard sphere” model ﬂawed? 1) { iii/2t} {geese Comet:ng Mm; Mil/5y iérgii {79% “(z/if“ 1}," “.35, 4L f9}. n J, #6
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c) The reaction A+ B ——> C gives a linear plot of ln[A] vs time therefore the mecth®e
A—> C . comment brieﬂy. g til it; Ed Pasé/ézééj we Get—X53545 $5.51 13% x” NET ‘7ng 53“”544’ @‘ME
Tease seem? a"? gig gates asst?” xiii??? f§§§5é§ d) What additional information can be found in the value of the Arrhenius constant A in the equation k 2 A eﬁEa/RT sf: .4; = ” » t“  W a use w ,i  m. , — ,:~ 3»; gm 5 67:”?th dying, % asfﬁégg ALié’XJiaéﬁ.) CM {5 ’1 ﬂ; Th: WWWz tits? e) explain with words and an equation if necessary why the half iife of a zero order reaction changes with the
initiai concentration while that of a ﬁrst order reaction does not?  2 : iagigj” 5 o to; hauler? <3 amt t& 7% f ;:;‘}‘gay' I, 15:1 . 3., {'4 «new— I 2:; Ug= QE— J?» ﬂa as A i: ~ M, . M.— rm m, ff 1/". .‘rﬁ’ Cﬂ‘gfr “9% i “5": “t W w r M r ’ v " i’
3” 1 N .,: a t i .4 if; a ., W e 6» ma
I’Lfgﬁ 9“"?! f 5 540” ‘54)” “a? mi“: M”; 97% xv $7310 "Tide;ng vs: C we
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i) For the reaction 3A + 213 —> 3C + 4 D The rate of formation of C 18 30 M/s What Is the rate of loss of/Aﬁﬂ} _ a . 2 ‘ r (2" E é; riket “:9 c: ‘5’“ 21:“ ,/,._~’ «I V Jigg g) for the reaction in (f) what are the values of m and n? R = k [A]m[B]n
CAI/0”?“ as 5 eve/2a ~qu to N30 “2’” M?
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This test prep was uploaded on 04/03/2008 for the course CHEM 480A taught by Professor Wesolowski during the Fall '07 term at University of Arizona Tucson.
 Fall '07
 Wesolowski

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