QUESTIONS BOOKLET. TEST OF GENERAL KNOWLEDGE ON CHEMISTRY FOR APPLICANTS TO THE GRADUATE PROGRAM OF THE DEPARTMENT OF CHEMISTRY 2 nd TERM/2016

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CHEMISTRY d TERM/016 JUNE 0 th, 016 INSTRUCTIONS - Red crefully the etire test. - Ech chose questio must be swered i the pproprite sheet of the swer booklet.

1 UNIVERSIDADE FEDERAL DE MINAS GERAIS Istituto de Ciêcis Exts - ICEx Deprtmeto de Químic Av. Pres. Atôio Crlos, 667, Pmpulh Belo Horizote, MG, Brsil Registrtio Number: QUESTIONS BOOLET TEST OF GENERAL NOWLEDGE ON CHEMISTRY FOR APPLICANTS TO THE GRADUATE PROGRAM OF THE DEPARTMENT OF CHEMISTRY d TERM/016 JUNE 0 th, 016 INSTRUCTIONS - Red crefully the etire test. - Ech chose questio must be swered i the pproprite sheet of the swer booklet. - Both questio d swer booklets re required to be retured upo completio of the test. - Ay electroic device must be tured off durig the test. CANDIDATES FOR MASTER OF SCIENCE DEGREE - Choose oly two (0) questios i ech re to swer. At the ed, you will hve swered eight (08) QUESTIONS. - WARNING: If you swer THREE (03) questios of the sme re, it will be evluted oly the TWO (0) formers. CANDIDATES FOR DOCTOR OF SCIENCE DEGREE - Choose oe (01) questio i ech re d other two (0) questios from y re to swer. At the ed, you will hve swered six (06) QUESTIONS. 1

2 AREA OF NOWLEGDE: ANALYTICAL CHEMISTRY AREA 1 QUESTION 1A A lyst prepred % (w/v) queous cetic cid (H 3 CCOOH) solutio d titrted ml of this solutio usig sodium hydroxide mol L -1 stdrd solutio s titrt. Durig the process, the ph of the medium ws moitored through ph meter with glss membre electrode. ) Wht ws the ph vlue of the medium idicted i ph meter whe the titrtio reched the equivlece poit? b) Wht should be the ph of the turig poit (titrtio ed poit) of theoreticl idictor to provide mximum error of +1.5% for the titrtio? Importt iformtio: p (H 3 CCOOH) = 4.75

3 AREA OF NOWLEGDE: ANALYTICAL CHEMISTRY AREA 1 QUESTION 1B Cosider solutio cotiig 0.05 mol L -1 of Ag + d 0.05 mol L -1 of Pb +, which ws titrted with potssium oxlte stdrd solutio ( C O 4 ). ) Which ctio will precipitte first? Expli presetig clcultios to prove your swer, if ecessry. b) Is it possible to precipitte these species selectively? Preset ll clcultios tht prove your swer. Importt: To chieve efficiet seprtio it is ecessry tht the remiig cocetrtio of the first ctio precipitted does ot exceed 0.1% of its lyticl cocetrtio whe the precipittio of the secod ctio iitite. Importt iformtio: sp Ag (C O 4 ) = sp Pb(C O 4 ) =

4 AREA OF NOWLEGDE: ANALYTICAL CHEMISTRY AREA 1 QUESTION 1C Figures below preset titrtio curves usig differet methodologies. Complete the prethesis "(...)" i the grphics, usig the optios (letter) locted t the right-side of ech figure. (A) ph of titrted solutio = 8.0 (B) poh of titrted solutio = 8.0 (C) ph of titrted solutio = 10.0 (D) p of cetic cid = Volume of tritt (EDTA, mol L -1 / ml) (E) AgCl ( sp = ) (F) AgBr ( sp = ) (G) AgI ( sp = ) Volume of tritt (AgNO 3, mol L -1 / ml) (H) EDTA (I) HCl (J) NOH () AgNO 3 Volume of tritt / ml 4

5 5 AREA OF NOWLEGDE: ANALYTICAL CHEMISTRY AREA 1 List of Equtios: L M / ) [... ( L L L 0 [ 1 1 L L 0 [ M c T M / [ L M ML... [ [ [ 1 0 C H H C H b C C H b C C p ph log x OH O H b w 1 [ [ 1 [ ps H H M S ) ( log 0 0 E cthode E ode [ [Re log Ox d E E

6 AREA OF NOWLEGDE: INORGANIC CHEMISTRY AREA QUESTION A Do wht you re sked i ech item below. ) A mierl group hs the geerl formul AB O 4, wherei the species A d B represet metl ios. Cosiderig tht the mierl is the husmite (M 3 O 4 ), cotiig M + d M 3+ ios, idicte the kid of coorditio (tetrhedrl or octhedrl) for ech ctio. Justify your swer by presetig the eergy digrms d rgumets of Crystl-Field Theory (CFT). b) Cosider the coordetio compouds bellow: I. hexmmiecoblt(ii) chloride II. hexmmiecoblt(iii) chloride III. tetrmiecoblt(ii) chloride Arrge these complexes i scedig order of the ligd-field splittig prmeter. Justify your swer. 6

7 AREA OF NOWLEGDE: INORGANIC CHEMISTRY AREA QUESTION B Crystl-Field Theory (CFT) is model which c be used to expli thermodymic, structurl, spectroscopic d mgetic properties. The figure below cotis the vritio of vlues of the lttice eergies for the third-period metl dichlorides. Cosider CFT rgumets d expli why: ) VCl is the compoud with the gretest devitio of the lie. b) CCl, MCl, d ZCl re the compouds with the smller devitio of the lie. c) ZCl is white solid. Figure 1. Vlues of the lttice eergies for the third-period metl dichlorides. The lie describes the theoreticl behvior for the vlues of Lttice Eergy. 7

8 AREA OF NOWLEGDE: INORGANIC CHEMISTRY AREA QUESTION C Cosider the structures of the followig ligds: ) Arrge the ligds i scedig order with respect to the cpcity to form complexes with high thermodymic stbility (higher vlue of formtio costt). b) Idicte the ligds tht fvor the occurrece of the chelte effect. c) Cosiderig tht metl io with electroic cofigurtio [r 4d 8 forms complex with the ligd show i (), idicte how my chelte rigs re formed d the umber of toms for ech of these rigs. d) Glycite (H NCH COO ) is bidette ligd d forms octhedrl complexes whe rects with Co 3+ io. Write the structures of ll isomers which my be formed. 8

9 AREA OF NOWLEGDE: ORGANIC CHEMISTRY AREA 3 QUESTION 3A The structure of cis-1,3-dimethylcyclohexe is preseted below. ) Represet the possible chi coformers d show explicitly ll bods betwee the rig crbo toms d H toms, s well s the bods betwee the rig crbo toms d the methyl group crbos. Expli i detils the reltive stbility of these coformers d idicte their distributio t the coformtiol equilibrium. b) Does cis-1,3-dimethylcyclohexe hs oe or more stereogeic ceters? I positive cse, idicte the stereogeic ceter(s) of the molecule, s well s the cofigurtio of the stereogeic ceter(s). c) Is cis-1,3-dimethylcyclohexe opticlly ctive? Expli your swer. 9

10 AREA OF NOWLEGDE: ORGANIC CHEMISTRY AREA 3 QUESTION 3B Two possible coditios for cid-bse rectios re preseted below. The solvet used for the rectios re idicted bove the rrows. ) CH 3 CH CH CH C C H + NNH NH 3 (liquid) b ) CH 3 CH CH CH C C H + NNH OH Write equtio, usig the curved-rrow ottio, for the forwrd d reverse cidbse rectios tht will tke plce whe ech of the bove compouds (solutios) re mixed. Idicte the equilibrium for both rectios. Idicte the vlece electros of ll toms ivolved i the cid-bse rectios. If the tom is chrged, idicte its respective chrge. To swer this questio, use the tble preseted below, tht cotis the p vlues for some compouds or the pproximte p vlues vlue for few clsses of compouds. Acid NH 3 + NH 4 H O H 3 O + + R OH R OH R C CH p

11 AREA OF NOWLEGDE: ORGANIC CHEMISTRY AREA 3 QUESTION 3C Whe the compoud I is treted with sodium methoxide (CH 3 O - N + ) i methol, mixture of compouds is obtied (II d III), beig II the mjor compoud. Whe the sme compoud I is treted with potssium tert-butoxide [(CH 3 ) 3 CO - + i tertbutol, the sme mixture of compouds (II d III) is obtied, but III is ow the mjor compoud. Whe compouds II d III re treted i the sme coditios (route 3), lcohols IV d V re obtied, respectively. However, whe both compouds (II d III) re treted i coditios of route 4, they provide the sme compoud VI. Bsed o this iformtio swer the followig questios: ) Give the structures of compouds I, II, III d VI. b) Expli the differece i proportio to formtio of the compouds I d II i the routes 1 d. c) Expli why i the route 4, i cotrry of route 3, there is the formtio of just oe product (compoud VI). 11

12 AREA OF NOWLEGDE: PHYSICAL CHEMISTRY AREA 4 QUESTION 4A mol of mootomic idel gs is crried through Crot cycle, opertig betwee the tempertures T 1 = 7 o C d T = 7 o C. If V 1 = 5 dm 3 d V = 10 dm 3, clculte the thermodymic qutities q, w d U i ech step. I dditio, clculte the Crot efficiecy d drw the digrm of the cycle usig T d H s vribles. 1

13 AREA OF NOWLEGDE: PHYSICAL CHEMISTRY AREA 4 QUESTION 4B Costruct the phse digrm for compoud A (i.e. oe compoet system) from the followig dt: (i) compoud A exists i two solid forms, S 1 d S, where the desities of both the solid forms re greter th tht of liquid phse, (ii) the meltig temperture of A is 0. o C uder its ow vpor pressure of 5.0 mmhg, (iii) phses S 1 d S d liquid re t equilibrium t 1000 tm d 70. o C, (iv) the trsitio temperture of solid phses icreses with the icrese of pressure, (v) the boilig temperture of liquid is 140 o C (t 1 tm), d (vi) if the solid form S 1 is heted slowly uder its ow vpor pressure it is coverted to S t 15 o C. 13

14 AREA OF NOWLEGDE: PHYSICAL CHEMISTRY AREA 4 QUESTION 4C The specific het cpcity of methe CH 4 (g) c be expressed by the equtio: C p = T T (cl o C -1 mol -1 ). Clculte the etropy vritio of mol of gs whe submitted to hetig from 300 to 600 t () costt pressure d (b) costt volume. 14

15 AREA OF NOWLEGDE: PHYSICAL CHEMISTRY AREA 4 Form R = tm L mol -1-1 = J mol -1-1 = cl -1 mol -1 =.0769 kp m 3 kg -1-1 N A = 6.05 x 10 3 prticles mol -1 1 P = 1 N m -1 = 10 5 br = (110 5 / ) tm 1tm = 760 mmhg 1 tm L = Joule Z = pv m /RT pv m = RT (p + /V m ) (V m b) = RT pv m = RT[1+B(T)/V m + C(T)/V m + D(T)/V 3 m +... du = Q + W H = U + pv dq rev = C p dt C V = (U/T) V C P = (H/T) P C P,m C V,m = R pv = cte T = T 1 (V 1 /V ) R/Cv = (1/V)(V/T) P ds = Q rev / T = (1/V)(V/P) T G=HTS A = U TS dg = Vdp - SdT dh = Vdp + TdS trsitio S trsitio T H trsitio V f T f T f S R l C v l C p l For solid d liquids Vi Ti Ti H 1 d l P dt R T If is fuctio of x d y, the: df f x y dx f y x dy P l P trsitio RT H m trsitios m T ou P l P trsitio RT H m trsitioh m RT Gibbs Phse rule: F = C P + F, freedom, C, compoets, P, phses. 15

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Definite Integral. The Left and Right Sums

Definite Integral. The Left and Right Sums Clculus Li Vs Defiite Itegrl. The Left d Right Sums The defiite itegrl rises from the questio of fidig the re betwee give curve d x-xis o itervl. The re uder curve c be esily clculted if the curve is give