Gujarat University 2005 B.Sc Chemistry Third Year - Question Paper

TB-04
Chemistry Paper-X

Seat No. :

Time : 3 Hours]

[Total Marks : 70

*l*Hl : (1) &iUl > UMVU p *R"il A.

(2) <HHl> VlMVll StR C-LMl.

1. -M Vi Tjei-ii >rcii6ii <a*i\ :

(a)    il&tt-U y-lM MHlpKa %l*i-il VR"i y-l UHU3L rll M Zlr\ [-i[l_ri iR$il ?

(b)    [cMmM ZHWMm-U aiferH VR ii -iTi C-L"!

(c)    yill[-li [cMmM Z.%iliSl*il isUZL-t-U Svl-tt aiaiL iZl. isUZL-t-{l lZ "ilillil PWUTr Zl-i-il SW.-L Wild.

(d)    i l&t[-U JlB *iiVll Svl-ll i Zcilil yicirll >'iir*ii [cMhSL U[rLyV{l lCl&-l?ll<lrll, aii.ia.l6 y-L [ciRlVdl VR ii -llU <l"l\.

(e)    [cMmM ZHW3l-{l    y-l ilsMPlrlk U[riyL Wild. yi u[riyl-{l cll>'Z.l%lll[l Vi[iyl %liL %iZ."il*iSil iZi.

(f)    >iirii ycm (pli) awid. [-ii<i iM-ii<a oeiidittti&iHl FueKl y-l ycPlPm ylittVUHl y<*i[5[-li*i-ll >T88ilr*i4 ycm-ft iirlZl iZi.

2. -ill-ll UMl-U WHl c-L"! :    (14)

(a)    vMzMs'U U[rLHl yq.?M cib-vicM-l. GrVllri .Wld. Mrl clb-nqM-. ytR iZ.rll vIZHqMl aiaii iZL.

(b)    VlrlL yivll Vl\il-?l*i\[5lirii y-JHmlHL q.lA<ai [$l irlL-Ll aiaiL iZl. Ll-l yiel"i-ll SudPirii wild.

(c)    yid-slMT. y-l yidQPl[ri y-i*iivi-ii qaaHi i iciri amd. ywlQP^;i[ri y-jHivL rii-i icisiLiL y-l yi*ilil[3i[ri yHiu-il yfeQi aiqisiLHl in Z.cil*il yici A ? KMnO₄ y-l K₂Cr₂O₇ -d y-JHlVLii rlZli RMlHll iZl.

yjcii

2.    -Mdi UMldi >"ciLH Cl"il :    (14)

(a)    mcjlrlis E&iali-i. vi.d 4L'<Jl l-.    aWld. rldi c[tLrLL pLi-tt *LH> 4-1 SUUlPidL 4LUl.

(b)    UlCUMs'li L[rtLL *J,"H Editi in clLl.clLlL 414 ? uWlilLS'lHL LLLi [c%i[ciH.LW. 4-1 &ted-i ii4 LL>Lcll. llCLlo-lLli U[rlHl ?U3L Editi in clLi.clLiL 4lC. ?

(c)    4-iLLl-li'L Lla[-$LlCl 4Lcl$UidL4l-{l 3i3il il. R *Vi-i i i4 LL>Lcll.

yWi

(c) l\aC-LLlCLCrlL [cMMMHl UM, [Erllu UiL 4-1 [-lU .il". ECUalidL Sul-il Lll il.

3.    -iMd! UMldi >clll dtl :    (14)

(a)    clli clll 4-l [$-R Ett-{l lL-ll iE lLLrLl U 4LHiftd ?

4PlL\H'3L 'lAalm'l 4-1 ml>d 'W.a'llLS'l clftl-i\ d riSicd. Wid.

yWi

(a)    ')>U\L$'1hL Ua [cldL 4-1 4CLLd Hia iiLd HLLCll Wid. 'W.a'llLS'lHi ciiRLdi S. -?lil >'LL^cl\. 4L S- &?liV{l yii.". ic.-dL Wid

(b)    iaislaMadL l -laii wid. 4L -.i -iai-. ii4 ccii. uv-vis lLa'la'lⁱtl.il d*i,d\ ll-'a. 4-1 -?li-{l clal ol\6cicil!1 4lci , ir! ULid lia'l'laLlla.lL d*i,dL-! *?ild 4-1 HVMte ciaal ii oQiAciLHl 4ici ?

ULWi&lcll 4-i $UHLd [cl[i.L iia clULrll SxlH -?li ULLC-iMdl GlLlL ULid [cl[i 3L Hia ii $LU d-ll ?

yWi

(b) Rta>H 4-i iCaL cli 4ill UiLL M &rl lclLl ? &l U-L-il Ricld! PiU?!-.    [clMMM liaiia'lila. cli cft .l i.cllil 4ici ? >\ illl

(ilM.) HiL?L fci>L-l CM. d V-L U34 85 iVsi UiL?L PlH MM U iLi! lU rll isad "![! 4Lcl?l ?

(c) icil h-ili -wi-tl [iM ? 4 hi4 awid.    mclsiImm

*Uiia\P{M xiicl Rl mr{[ xi[riMl .Wld. XL.iLL[iLh =H<ttl\H'3l

xll[i[h 6RL MHlrLMVi [cLMh'SI hi SlA-l d-Ll ?

WWl

(c) (i) Ml-ld [CL[-lliL *'LLaLll^rll'L Ml-.d [CL[-lliL LriCl-L-Ll Moir-L Mo\ ilill is3i.

Ml-ld [cL[rLLiL 3[d-{l [xLLrLL-L M*R iRd'l xl[3h.\ Wild.

(ii) sMPilrLM. ".[L ah dlH CL"iL.

4. (a) -M xLhl C. -Ll ciiiL CL"ii :    (14)

(i)    Mfei-S.6tt MHind SPi-ld qMiciiHl-Ll h M-iHixLddl Lcm1.hMI XlC-Sldl CO₂ -ft M*R-Ll ilill h3L. Ml ".[?{-. [-.cRii M . h& LhlL ?

(ii)    MlChcll i-ll^T"Ll^T"ll [ClhL[-L--l M-LHLUd 6RL dA M . -1 hLl h MlChC-Lldl MlXLclL dl{d\

(1)    LlCiLL siMsI-ia M-l llCiLL MHi-ia *Ric. .

(2)    sm LiCiLi Msl-ia tRiC. .

(3)    *lL[1-.h i6iLii6i M-l    hiHl-La tRic. .

(iii)    HCl y.lA NaOg dl MHind-tt y.H> MLUl.

(iv)    25 PU-Ll. 0.1M lCL6h (Maleic) Mkli, C₂H₂(COOH)₂, 0.1M NaOH *LLi MHind-l MlCL"i [-.Wld. Lcih Mfeidl K_j M-l K₂ C-lL M'l

1.2 x 10^-2 M-l 5.96 x 10^-7 .

(b) -M Xih! Cl -1 >-ciisl -{"ii :

(i)    EDTA MHind! M"ir-lR iRci-fl. iiii xL[rLM\ cld. XL-1h xi[rLdl 1-1-1 Wild.

(ii)    XLllMl i;lddl [-.(Md h.c{l Hdl MHlX-dHl -iiil xLHU3lHl MgY^--xLULIhL h;H SIrcM Mici ?

(iii)    50 Pu-Ll. 0.05M Ca++ dl l-i 0.01M EDTA ci 10 pH *i 4.ciiiiL Miclrll M{iilXL^T"L^T"Li MlCL"l PiWld. 10 Pi.-Ll. EDTA SRdl riW LiiriC-L [Sl-M pCa cd-fl. oi. $d. 10 pH {C-i a₄ C-L 0.35 .

CaY -{{ [*-Rdl MiWlh 5.0 x 10¹⁰ .

(iv)    EDTA MHin-Hl c{[Lti_rii x. HlRhoi, Unicoi M-l pH -Ll M*R-il ilill -iio-i Gali Mixll h3i.

(a)    iL : uCi-ft akrilHl &l LSlt ctURl iCA-tl i pH Hi yi yiH-lt C.Ur\ ivu-l HlrtilCLa-tt [->i*fel il4"tHdl MR *R"tl > y*R 8iii .

(b)    yact ?l ? yi -ta-U-l icll . [-lclll lilil ? URd (digestion), U(d.yW.d *rR, "t y[dt yrtvll Tlillill-ll cill"ill yid.

(c)    AgNO₃ %Llt Cl^- -ll hL3. yHlUdHL lli K₂CrO₄ -tl Wl akdl-tl ISldil iL. AgCl y-l Ag₂CrO₄ -ll l-lcll ISlliR y-t't 1.2 x 10^-10 y-L 1.7 x 10^-12 . hLr y-iHtud cia-L i %l4> ytciaid lcmhi in i.clill yiCl ? yi*ilsi&-i y-iHtud hLr u(Ml isH nit. -i-Ll ?

(d)    ?U3l ylMlxSl -Mitdl LU6.L y-l kSW.-l-tt 3l3lL iL.

(e)    clL-i cu6h4 p'trR ?l ? d.Hl %L*iLlCiL U-Wl c*tfwti yiut. yq."tud *il-UL $*t\3*t y.>M yl dl ?H *ii[rUl hQ ?

(f)    [ y-l u[[; "t[dt y-L [CtUC-Ld l-Ll HMi (mean) y-t HM*t (median) -il y-L awtd. ii*ii[SLdi [CuicL-t-d %lh> yiut. PMti "i[ri y-l yFt3iL*ti "t[dt yacl ?t ?

Instruction : (1) All questions carry equal marks.

(2) Attempt all questions.

1. Answer any three of the following :

(a)    How will you detect and determine a carbonyl group in an organic compound ?

(b)    Write a note on Literature of Analytical Chemistry.

(c)    Discuss the use of Cupferron in Inorganic analysis. What is the advantage of Neocupferron over Cupferron ?

(d)    Write a note on sensitivity, accuracy and specificity of gravimetric methods using organic reagents.

(e)    What are the various spectroscopic and spectrophotometric methods of analysis ? Compare them with electrochemical methods.

(f)    Explain Gravimetric factor. Calculate the gravimetric factor for Nickel in Nickel dimethylglyozime and for Aluminium in Aluminium oxinate.

2. Answer the following :

(a)    Explain the origin of Residual current in polarography. Discuss the factors affecting limiting current.

(b)    Giving examples, discuss the principle involved in potentiometric titrations. Explain the utility of Grans Plot.

(c)    Explain the difference between iodometry and iodimetry. Why iodimetric

titrations are performed in neutral solutions and iodometric titrations are performed in acidic solutions ? Compare KMnO₄ and K₂Cr₂O₇ as titrants.

OR

2. (a) Giving an illustration explain the working mechanism of an ion-selective electrode. Explain its selectivity coefficient and its use.

(b)    Why a small electrode is used in polarography ? Explain the function of supporting electrolyte and gelatin in polarography. Why three electrodes are used in polarography ?

(c)    Discuss the potential requirements for redox titrations. Explain the function of a salt bridge.

OR

(c) Discuss the use of electrodes of the first kind, the second kind & the inert redox electrode in potentiometric analysis.

3. Answer the following :

(a) What considerations govern the choice of the carrier gas and stationary phase in chromatography ? Describe the fundamental difference between adsorption and partition chromatography.

OR

(a)    List the variables that lead to band broadening and band separation in chromatography. Describe any two detectors used in gas chromatography. What are their relative merits ?

(b)    What are the essential components of a spectrophotometer ? Describe the function of each. Why is the sample compartment located between the monochromator and the detector in UV-Vis spectrophotometer but between the source and the monochromator in infrared spectrophotometer ?

Why cannot the excellent detector systems available for UV and visible radiations be used with infrared radiation ?

OR

(b)    How a monochromatic light is obtained by a prism and a grating ? Explain how a mixture of two substances can be determined simultaneously by a spectrophotometer. If the cell is not exactly perpendicular to the beam but falls at an angle of 85 what error will result ?

(c)    What is the necessity of a hollow cathode lamp ? Explain its working. Explain the methods used for background correction in atomic absorption spectroscopy. Why non-metals are not determined by AAS ?

OR

(c) (i) Discuss the importance of ion exchange equilibria in ion-exchange chromatography. Describe factors that affect the selectivity of ion exchange resins.

(ii) Write a note on photometric error.

4. (a) Answer any two of the following :    (14)

(i)    Discuss the effect of CO₂ introduced during an acid-base titration, either

from the atmosphere or from the titrating solutions. How this error may be eliminated ?

(ii)    By differential titration of alkalies, how will you know whether a given sample of alkali contains :

(1)    Sodium bicarbonate and sodium carbonate?

(2)    Only sodium carbonate?

(3)    Sodium hydroxide and sodium carbonate?

(iii)    Explain the titration of Na₂CO₃ against HCl.

(iv)    Construct a curve for the titration of 25 ml. of 0.1 M maleic acid, C₂H₂(COOH)₂ with 0.1 M NaOH. K₁ and K₂ of maleic acid are

respectively 1.2 x 10^-2 and 5.96 x 10^-7.

(b) Answer any two of the following :

(i)    Describe three general methods for performing EDTA titrations. What are the advantages of each ?

(ii)    Why a small amount of MgY^-- often added to a solution that is to be titrated for hardness ?

(iii)    Derive a curve for the titration of 50 ml. of 0.005 M Ca⁺⁺ with 0.01 M

EDTA in a solution buffered to pH 10. Calculate pCa values on addition of 10 ml EDTA and at the equivalence point. a₄ at pH 10 is 0.35. The

stability constant of CaY is 5.0 x 10¹⁰.

(iv)    Discuss giving suitable examples the effect of masking, demasking and control of pH on the selectivity of EDTA titrations.

(a)    Prove that a tenfold increase in the reagent concentration will increase the extraction efficiency by same amount as an increase in the pH of one unit.

(b)    What is peptization ? How is it avoided ?

Define : Digestion, Counter-ion layer, Relative supersaturation.

(c)    In Mohr titration of Cl^- against AgNO₃, calculate the concentration of indicator, K₂CrO₄, required. The solubility products of AgCl and Ag₂CrO₄ are

1.2 x 10^-10 and 1.7 x 10^-12 respectively. Why Mohr titration is performed in neutral or slightly alkaline solution? Why I^- cannot be titrated by Mohr method ?

(d)    Discuss the advantages and disadvantages of three adsorption indicators.

(e)    What is Von Wiemarn ratio ? Define the terms involved. What information concerning the optimum conditions for precipitation does it give ?

(f)    Explain : Accuracy and Precision; Error and Deviation; Mean and Median.

Explain standard deviation. What is meant by determinate error and indeterminate error ?

TB-04    8

Attachment: gujarat-university-2005-b-sc-chemistry-33429-1.pdf

Earning:   Approval pending.