Gujarat University 2005 B.Sc Chemistry Third Year - - X - Question Paper
Seat No. :
Time : 3 Hours]
[Total Marks : 70
ijHl : (1) HHl > UMVU p ilML .
(2) <HHL> UMVU tL L"ll.
(14)
(a) il&tFU W>H.HL iLLl[-lCl il! iR"l UHLL rll M lrl [-itLrl il ?
(b) [cMSl .LLLLLLL-IL iLLrL M i -HL CL"ll.
(c) =Hi L-lPli [LcLhL .iLLilLLL i Tr[L-l-lL GxlLl0 Lil aiail il iHVifl. L."!LLLIlL [.ililLLL LL-L Wld.
(d) i Ll[Li n[Li.-lL GUil-ll i VllhL Lcirll >"--lLrHi fMSl UrlHl-il iLL--lllCLrLL, LliiLL =HL [L[L4rLL M i ilU CL"!.
(e) [CMSi iLLiMll Ll L Wld. L L [lLl cil>lilli.flii Ulrl. iLL-l L."LLLll iL.
(f) >llrli cLMA (pii) LWlc|l. [LiCL iM-LlCL CLLiLlLLLL [LiCLll l Cl[l[Lll =H.i..Hi Cl[;l[LLLLL --LlrHi ciiicill oiidil i3.
2. LlLLl UmViL >-ciL6i\ CL"il : (14)
(a) HlLS'U U[rLHl >0. clb'HCM! rl[Tl .Wlc|l. illPlrL cilciiL =H i3.rLL l[.&llil Lll iL.
(b) SVld Ll Ul[$Lill[;l[riil LlLLlill ililLcil [LlrLlil Lli i3. LLL :HLLM-{l UiPlrLL Wld.
(c) l Lll[[l[rL LlLLil cialLi L Lcirl LWicil. LilQPlCrL LlLLil rL4i-L LclLlll i -iMPlIxl 111111 flQi LciLllL in
iiciiHl ici ? KMnO4 =HL K2Cr2O7 il HlUi. rl&i ilMLHll i3.
jcll
2. -M-U ULMVu >cill CL"! : (14)
(a) L-tClrli &iU-l VLd iM! ri-j -L LWLcl!. L-U [riLrLL opli-l LW -l 6u4ldl LUi.
(b) ULLoUS'li U[rLHL I,"H C.i\ iH ciLU-CiLHl lL ? uWlOlLSlHL llli (CidCMlW. =H-i. fd-j. M*l LWLCl Ui.OlLS'li U [tLHL ?U3l CL\ iH cLlxl.cill iC. ?
(c) .'l". -HlU-lM l[-LLCL Lcllrlll-{l li iL. "lL 4-I ill LWLCl
(c) UlplllP[rll [CICLLLL U-LH UM, friU-l Mlil -L [->1 Lii.dl 0lLll-{l ll il.
3. -Mdl UmVu Ciii CL"il : (14)
(a) '.LolLS'lHL ciii c{ii -{ [-r -{l ll-oll LLlrLl U LHlCd ? PilMM 'iOllSl -L mi>d 'iOllSl c{l-i\ L dSLCd. Wiel.
(a) 'i>LiOUSrlHL U (Cirii -{ h Cioi-i Hl Md lilLCll Wiel. 'iOUS'i.HL ciULdl L -.i'l Wiel l l-i -liVl illM" Lc{tIL Wicl
(b) Lii'lil.-ll >l -lii. Wld. L &.i -{i-j. ill cilcll. UV-Vis Ma.S.MHL d*j,d\ hVL* -l -li-il c{l oilciciiHi iC. , U4 ULAd .S.l*lHl ddl-L llri =H-L HVMte Ci. i lliACM iC. ?
MR>LC'il -L LHLd ftl Hl q.ULcil 6xlH -i UllC'LMdi. 6ulLoi ULAd (Ciil LL iH LM. --Ll ?
(b) RlH -L {[l .i.oLl Uill M lrl cui ? L XL-L-li tL.LclrLL (iLl-i LH"lfld [CMM M.4-.S.M C. icll lrl iciiil iC. ? >\ xlll (ili.) liLL [LL-l 6LL d li XL.r 85 ti MiiLL [LL MM U Uri 1L rii Cil "{[i Lcii ?
(c) C Md -t-il l (-lld ? - hll iwicl. T.*[ cHl Uhi.[;i[M UlM lURl *-l t[r.\ lWlcjl. T.*iCr cHl .[i 6. Hl-. Cliii hH ii --l ?
(c) (i) id [C.PiHl llalll =Hl*M [C.[-iHl C-idl-l lrl o\ l ii.
id [C.[-m .[--l [.idl- .l hl uCHl Wld.
(ii) sM[l[rW. "[ U h -l "i.
4. (a) -M th. l -il cii <a*l : (14)
(i) .[id-t -l*lT- 6..[ii- clllciiil-l h -*x-- lci3Hl-l tlClrl CO2 -il R-l 33 hi. =Hl "[-j [-iciil M ll hl lh l ?
(ii) =HlCh<l iii>'dVii [Clh<[-ll -HlUd 6Rl l M li d' hl h =HlChl-l ftteli -ll-l
(1) l[dlH HI$MH- =H-. l\[li MHW. tRlC. .
(2) Ad l[* MHR lCl .
(3) l[* llll& =H-. l[dlH hIH-U .ll .
(iii) HCl lll Na2CO3 -il -JHlUd-l lW =Hl<l\.
(iv) 25 [i.cil. O.lM HC<th (Maleic) .[ld, C2H2(COOH)2, - O.lM NaOH lli -HlUdd. =HlCi*l [-iWlcil. Heltfh .[iddl K1 =H-l K2 C-i - l.2 x lO-2 -l 5.96 x lO-7 .
(b) -M th. l -il WHl C"t :
(i) EDTA -JHlUdi. HHcHl iRCA-l i iiHl-. t[,\ cici. tllh U[rdl ll-l Wld.
(ii) tiil-l hl-irii C-[li hcil l-ll -JHlUdHl -ldi tlllll MgY--tU3lHl hH 0l.ci l. ?
(iii) 50 [.Cl. 0.05M Ca++ -il lcl O.OlM EDTA cid lO pH *J<l hini lrll HlUdd. ic"l [-.Wld. lO [l.Cl. EDTA 0.ll W lHi<l [5l- pCa C*iMl l'Sldl R. lO pH lCl a4 -j <l 0.35 .
CaY -ii [-i.ril Ilh 5.0 x 101G .
(iv) EDTA -JHlUdi-il ct[rilll U ll[hl, dlil[hl -l pH -il R-l ll ii aI itll hl.
(a) L-Cil ii : H[ir-il krilHl -l lLi q.Uli .cil-il i pH il .i .iH-ii ciUli icii-il .ilC-l [->ifel il"lHll U l."tl > =H. ili .
(b) K .i l ? =Hl .-il-i cil li [-iciil lill ? Tiii-i (digestion), nClil-i l, .lL"L [i iivil Tiill-il cii"ii lli.
(c) AgNO3 lll Cl- -il hU HlU-tHi lli K2CrO4 -l l lLril-il lldl ii. AgCl =H-. Ag2CrO4 -il iciril lliR -'l 1.2 x 10-10 =H-.
1.7 x 10-12 . hU -iiTi-i i-i i .4> =Hie*ai&i icsini. h i.ciiii =Hli ? -Ul-. .-JHlU-t H U(Ml H il lili -l-il ?
(d) ?U3l (MXI -HiVil ll-l =H-. .SW.-l-l -l-li ii.
(e) cli-i cuH- oiLTl l ? Lli llllil U-Vl cii"ii lUi. HctfliK ii-ii ilii l>M o\ i il HlM l ?
(f) l[ Hte; "l[i [ci-e-i l-il Hli (mean) =H-. H-l-i (median) -ii l lWicii. UHlld [ci-ic-i-il ll> Hl<i\. Ftelfai "l[l =H-. [-Mfoi "l[i .d l ?
Chemistry Paper-X Time : 3 Hours] [Total Marks
Instruction : (1) All questions carry equal marks.
(2) Attempt all questions.
1. Answer any three of the following :
(14)
(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 :
(14)
(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.
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.
(c) Discuss the use of electrodes of the first kind, the second kind & the inert redox electrode in potentiometric analysis.
3. Answer the following :
(14)
(a) What considerations govern the choice of the carrier gas and stationary phase in chromatography ? Describe the fundamental difference between adsorption and partition chromatography.
(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 ?
(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 ?
(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
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