National Institute of Technology 2007 B.E Chemical Engineering End Semester - Question Paper

Max. Marks: 80

National Institute of Technology Karnataka, Surathkal DEPARTMENT OF CHEMISTRY
End Semester exam CY 300, Instrumental Methods of Analysis

Time: three Hours
Note: ans all the ques.
1. Justify he following:

i) In the conductometric titration of a mixture of strong acid and weak acid the plot
is curved near both the end points.
ii) Redox titrations can not be carried out as conductometric titrations. iii) There is a sharp increase in the potential near the end point in the potentiometric
titration of Mohr's salt solution with dichromate solution, iv) In the polarographic analysis, the working electrode is a micro electrode and the
reference electrode is a macro electrode, v) Addition of complexing agents facilitate the simultaneous polarographic analysis
of metal ions having small differences in their half wave potentials. (10)
2.
i) Derive polarographic wave formula.
ii) discuss the principle of amperometric titration by taking the example of titration
of Pb2+ solution with SO42' solution, iii) Name the indicator electrodes that can be used in the subsequent titrations:
a) NaCl solution with Lead nitrate solution
b) Magnesium sulfate solution with EDTA solution. (4 + four + 2)
3. Justify the following:
i) A linear molecule AB2 is IR active but not microwave active.
ii) IR spectra can be used to identify the cis and trans isomers of a compound.
iii) At high concentration of the analyte, Beer's legal regulations is not obeyed. (6)
4.
i) discuss the origin of P, Q and R bands in the rotational vibrational spectra of a simple harmonic oscillator molecule.
ii) Name the possible kinds of electronic transitions in an unsaturated organic acid. organize them in the increasing order of the frequency of absorption in the uv-visible region, with justification.
iii) Bond length of a diatomic molecule AB is 1.4 A°. Atomic weights of A and B
are 12 and 16 respectively. If 1 of the rotational absorption lines of the
molecule is at 12.3428 cm^-1, compute the wave numbers of the next two
successive lines in the spectrum. (6 + four + 4)
5. Justify the following:
i) In the determination of Ca2+ by AAS method, the solution is mixed with Na+
ions, ii) DTA but not TG is used for the study of a physical modifications.
iii) The solvents used in the solvent extraction should differ appreciably in their
densities. (6)
i) discuss the principle of AAS.
ii) Derive an expression for the amount of solute remains un extracted, after n extractions. Also derive the expression for the percentage extracted.
iii) A compound AB2C3O6 exists as AB2C2O5 ranging from 150 - 220°C, AB2CO3
ranging from 300 - 350°C, ABCO2 ranging from 400 - 440°C and as ABO above 650°C.
a different compound P2Q2C2O6 exists as P2Q2CO4 ranging from 140 - 190°C, P2QCO3
ranging from 390 - 430°C, PQCO2 ranging from 650 - 750°C and as PQO above 850°C.
360 mg of the mixture containing AB2C3O6 and P2Q2C2O6, on TG analysis,
weighed 310 mg at 180°C, 189 mg at 410°C, 135 mg at 700°C and 121 mg at
900°C. compute the composition of the mixture.(molar) (4 + six + 4)
i) describe distribution constant, retention time, retention factor and derive the
relation ranging from them, ii) discuss the principle of paper chromatography. How is it used for qualitative and
quantitative analysis?
iii) provide an account of the kinds of columns use in gas chromatography
. iv) What is a guard column in HPLC? elaborate its functions? (6 + six + five + 3)

Earning:   Approval pending.