Chemistry 271, Section 21xxUniversity of Maryland, College parkGeneral Chemistry and EnergeticsExam I (100 points total)pH = - log([H-])AG=AH-f .tAGo = - RTlnK,,n,ln,, - exp[-(Ei- E()lkn?IProf. Jason KahnMarch 14.2007You have 50 minutes for this exam.Exams written in pencil or erasable ink will not be re-graded under any circumstances.Explanations should be concise and clear. I have given you more space than you should need. There is extraspace on the last page if you need it.You will need a calculator for this exam. No other study aids or materials are permitted.Generous partial credit will be given, i.e.,if you don't know, guess.Useful Equations:A.S- qlT>0S = klnWK,, = lH*ftA-l/tHAlW = N!/(lI ni!)Hollor Pledge: At the end of the examination time . please write out the following sentence and sign it. ortalk to me about it:"l pledge on my honor that I have not given or received any unauthorized assistance on this examination.,,l ' (12 pts) Calculate the pH of a 0.150 M solution of nirrous acid, HNoz, pKa = 3.35, assuming rhat youorsunr ,.4{i1{\)c(uTF ,^* 4.rrl, wl, olc,,v,awfrv*V f, , tt',hl ,/ ph wout/,L=mc'PV = nRTe'"+l=09cavvqdvfrhl^L@[ = -loS k\Score for the ,ur, I n^Chemistry 271. section 2lxx Eram I. 3/14/07 ZnZ, Creatinine, shown to the right, is a breakdown product ofmuscle creatine. Decreased creatinine clearance from theblood is one of the main diagnostic indicators of late-stagekidney disease.(a; 10 pts) Sketch the titration curve of creatinine with strongbase. Indicate the two buffering regimes and the firstequivalence point, and their corresponding pH,s. Don'tworry about the exact pH's at the beginning and end ofthe titration.[oalr. \ at a.tu,rl_2,,.\4f ,^\nle.<<folafLtJ t -((<.,>Sfca!}/>t-lc|lwV.lucoP 0 '\^rCreatininepKal = 4.8pKa2 = 9.2r-IHPKEr{L,(ltoqI+(,tY,z- -*(&'V -fou 4 -f o^vt)+ l 4- 'G' ob*bQ-\"*,fCv(,/r/'C-.fL €t- sb(t- pr.r- r\b*(11-,a,a,*:'ry;t*Y -* "n6t:n (ebf uo 6 *5 6- t,."k(gL b^(1+fL m/rw + fluitJacc pvb. chris h*1, J%X +L Cr o''/^ cntn*-2" ftA (ttut6rb)(b; 5 pts) Draw the structure of creatinine at pH ll. and rationalize wh), the anion is so stable relative tothe anion that would come from deprotonation of di-isopropylamine.t?€/' +( €.a" Qu,b>t+ I 6"r .J "n""'f 7 nb re"wA€tr tt 7-,1rr.0r.. t'{- <ih*. q clcrbl., r bv,*-ls l?*tr *6vr.,l'gt e(1(on( ; P h>,f n^-(<c c- Jct$ tt l" LD\+lfL@n2wL}^nJ ^rr;{/>,1lH,hu$Ir"Eu'hOOAr)r cft.r{ 9Hs'i IH-]-N'. ,'I ,ENG)2-n' tH\", \H| | Di-isopropylamineN-'\ PKa -36yt& ft. vAf ^ht*-hwScore for the pug"---I;3' "lron fertilization" is a proposed method of ameliorating global clirnate change by stimulating thegrowth of marine algae, through dumping relative small amounts of iron (i.e. truckloads) into the openocean' How can adding (relatively) so little iron possibly make such a big difference? The solubilityproperties of iron are informative in this regard.consider iron(lll) or ferric hydroxide, Fe(oH)r. Its K,, at25 oC is 2.6 x l0re.(b; 6 pts) What is the concentration of Fe*3 in water at pH g?/ r, Q. ,Wot,/.+ evfx.l a>\ t-nt'J\( - { ,G,r Lk*tj + [nu-] )@(f U f- nq*r<ttc-l ,rrr.lL h,* "tt^+ ila* )I rn"-J :lo-'' ro- tYm: G"= to-en+l 6- nup^t?,Ull.-f yo^ y"ezrl l"crl4-ul'rt, ttt o'l )Lr;'J2,(2xrc-tq(,.rz, (, lo-zt n€9 k c-s,a-lde+ 5at",l5 I,nh+3 c.",,.lis W lu*( o'^g,trtr r-r(^)score forthe ou,.. f lYChemistn'271- section 2lrx Fxam | 3ll,1lO74. The Boltzmann distribution for three differenttemperatures is shown at the right.(a; 6 pts) Identify which distribution is which bywriting Low T, Medium T, and High T inthe boxes.(b; 6 pts) Which distribution has the largestvalue of W, and why (l do not want anumerical answer, but it should be based onthe equation I gave you for W)?bi ^ r @.-,!Lr^ Qr '^org o(:fk""t@ v*f fu liltv:v'"'(e- ftuu&'*t"T*lA *^? s l<kr'&(tlL8olrl'1f0cl) - v'1'Qra [<*G -n *alc4 rl^cr^ Kb r^r ofir- taaV- flo t l- ?t*rrntW yrctL aL b z.Jtrf-.-r ts *5"[ftu^flg ol,fft,a'-f4 tt iL*st* a^il'* foo+" Lx. ObX4nl ,s'nficJ'b-vtloh.-etIvrrf,. A- I ro,As (renrt7 Nc.daG.r fu hf^1. tu!qY a .\ rr 2 tU(1'-.-r J thri L,,htr ,,=r(n*(o,ut. l<*Q +7'il tmzttvsP -."n.rt!,? f" tt^ 7 A9-,,ofhB?ca,^r. 4-* dtWlL^(;; t & l'';r2 Pu(ce'{,@@ov&-^i J'^ (),/.1 1!:-""-/r'-J"}::l--)ekL.'ry\ W aU Torr n'b-57.w [/=lt s"orlr tuaL luJ uJa^t^Boltzmann Distribution@w:(c; 3 pts) If the universe always tends to larger W, why isn't the distribution you picked in (b) alwaysthe one that we observe , at any temperature? (Sort of a trick question).@ (.t'l<rv "tt" "( *,,tl r Q.r ,-(k kJ rh rti = fio€(d; 5 pts) In general terms, explain why the Boltzmann distribution is the actual distribution observed,as opposed to, for example, a configuration in which every nrolecule has the same energy.Score for the page5' (10 pts) Thermodynamics. consider the equation A.s - qlr> o,which is true for any spontaneousprocess.; it may help you to consider theprevious problem on the exam.E^ $,p6fr +a sysla'^s @@-t(l = l"-4"1"o*r(.rral h &tutrrn4r'(i@@I /f a^.3cr bu-,-. o* ,*r-I- , &,? nr.tV 1,4nvitt>-t4^f W tt* lu ^saa-<f nr.VA iv",,s k"rul e'f hty tT.f-i.,tr 6111,u"(* -(xo lt.tn^,r,Y ts twr< il^ynrh-f ,i low 1+n7,,^/r^,ca.6' Consider the equilibrium below, which refers to a protein p that must form a dimer in order to bind toDNA.2P +D =+ PzD(a; 3 pts) write down the equiribrium constant Kr,,,,for the reaction.l( g,r-.t =fPlpJ[p]' [bJIeJtoJ(b; 6 pts) we would like to be able to do an experiment to measure the equilibrium constant. Typicallywe can measure IPrDl, and we control the total concentration of DNA (Dr) and the totalconcentration of protein (Pr) in the tube. Use the conservation equations for total protein and totalDNA(forexamp|e,weknowthatD.,=JD]+tP,D|)to@intermsoflPrDl, D-r, and p.,-.)r = tuJ* [P, btt "2" i; _,arr<nf,, b.* ..(uU ,rrX.r ir s,v<*6- f7. 1r,jrlrtt'J >\ (t 6'v^ reV:ul /'-'r\ ve- s6csa.-t"t i^@ f,- cotrcc-.|-+/^Ad4)-rf+ I (T qnu ft,ut'""/+L fu J*/- _tP"oJPr=\PK.$.?,D1 /@Kr.* =(r, ={p,DJ)'(1,l,r-r- lt^413\q ct LQ fr6n ')^ IPrUJ+" h)It'. u 1^ llruJ)Score for the our f t1Chcrnistr)'271. section 2lrx Exam I.3/14/07 6n(c; 6 pts) This equation is too difficult to work with, being a cubic equation in lPrDl (that was a hint...).Under some conditions, we can simplify. Assuming that P, >> lPzDLsohe the resulting linearequation for IPrDl as a function of Kr,,,u, Dr, and Pr.Ku,*t = , @t':'"w,tr1t4-\Jo @ nr- req,:t J lt-, f ^ ry(+LPgDJ ncn %t/ LP'll 'l(e,r.-{ = F;-t(v-[p.Dl)r-,-,1 DcPrtl(r,^,tQY"*t4Fl, 5o(tlc(vn-.t PrL (l, - tP"Dl)