Please answer in your own words; do not copy from the course material. 1. a) What are the major ... b) Deduce the Nernst
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ASSIGNMENT BOOKLET
Post Graduate Diploma in Analytical Chemistry (PGDAC) Basic Analytical Chemistry
(MCH – 001)
Separation Methods
(MCH – 002)
Spectroscopic Methods
(MCH – 003)
Electroanalytical &Other Methods (MCH – 004)
(Valid from January 1, 2018 to December 31, 2018)
It is compulsory to submit the assignments before filling in the examination form.
School of Sciences
Indira Gandhi National Open University Maidan Garhi, New Delhi-110068 (2018)
Dear Learner, This assignment booklet consists of the tutor marked assignments (TMAs) of MCH-001, MCH-002, MCH–003 and MCH–004 courses of the Post Graduate Diploma in Analytical Chemistry (PGDAC) programme. We hope, you are familiar with the system of evaluation to be followed for this Programme. You may probably like to re-read the section on assignments in the Programme Guide that was sent to you earlier. As you are aware, a weightage of 30 percent has been earmarked for continuous evaluation component. For this you have to submit the responses of the enclosed tutor marked assignments to the Study Centre Coordinator. The assignments are based on the content of all the blocks of all the courses. Before attempting the assignment, please read the following instructions carefully. 1
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Though the validity of assignment is for one year, we advise you to submit the assignment response within 12 weeks after receiving it. We strongly suggest that you should retain a copy of your assignment responses.
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Wishing you good luck
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TUTOR MARKED ASSIGNMENT MCH-001: Basic Analytical Chemistry Course Code: MCH-001 Assignment Code: MCH -001/TMA/2018 Maximum Marks: 100
Note: * This assignment is based on the entire course. * All questions are compulsory. Marks for the questions are shown within brackets on the r.h.s. * Please answer in your own words; do not copy from the course material.
1.
a)
What are the major contributions in the present multiple opportunities of (5) analytical chemistry?
b)
In an analysis a value of 6.34g is observed whereas the true value is (5) 6.38g. What is the relative error in parts per thousand?
2.
What are the three ways in which the percentage in liquid samples is expressed?
(10)
3.
a)
What is the meaning of confidence interval with respect to evaluation of (5) analytical data?
b)
Briefly describe any two sampling equipments.
(5)
4.
Regarding the code of practice in a laboratory, what are the points that one should (10) remember regarding handling test-tubes while heating or adding reagents and while diluting strong acids? How would protective devices minimise risks in these cases?
5.
a)
Urea of concentration 0.1mM was hydrolysed using increase of concentration of (5) 10.0 micro mole. Using the values k2 = 6 × 104s-1 and Michaelis constant for urease 2.0 m M. Calculate the initial rate of the reaction.
b)
Calculate the [OH-] of 1.0 M Na2CO3 (Kw = 1.10 × 10-14, K1 = 4.2 × 10-6 and (5) K2 = 4.8 × 10-10 for H2CO3)
6.
Explain with suitable examples and equation the titration of polyprotic acid versus (10) strong base.
7.
a)
Explain the classification of nonaqueous solvents.
(5)
b)
Deduce the Nernst equation for a dichromate ion to trivalent chromium ion reduction in acidic condition.
(5)
8.
What are the applications of complexometric titrations. Give suitable examples.
9.
Explain with a suitable graph the titration of “Iodide-Chloride mixture with Silver (10) ion”. Discuss the factors on which the sharpness of end point depend.
10. a) b)
(10)
How are the anions generated by hydrolysis?
(5)
Write a short note on inductively coupled plasma.
(5)
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TUTOR MARKED ASSIGNMENT MCH-002: Separation Methods Course Code: MCH-002 Assignment Code: MCH -002/TMA/2018 Maximum Marks: 100
Note: * This assignment is based on the entire course. * All questions are compulsory. Marks for the questions are shown within brackets on the right hand side. * Please answer in your own words; do not copy from the course material.
1.
Discuss various factors which govern the classification of separation methods.
(5)
2.
Briefly explain various types of distillations.
(5)
3.
Discuss various ways in which multiple extractions are carried out.
(5)
4.
What is a modifier? Why are modifiers used?
(5)
5.
What are metal chelates? Give the names and the structures of two important chelating agents.
(5)
6.
How does the presence of masking agents affect the extraction process? Explain.
(5)
7.
Discuss important aspects of supercritical chromatography.
(5)
8.
Illustrate the process of separation of components of a mixture by column chromatography.
(5)
9.
List the requirements of an ideal support material used in liquid-liquid chromatography.
(5)
10. Describe various methods used in the detection of spots in TLC.
(5)
11. List various factors which contribute to broadening of a bond in gas chromatography. Write the expanded form of van Deemter equation and give the significance of various terms appearing in it.
(5)
12. What are super selective liquid phases? Illustrate with the help of examples.
(5)
13. What is gradient elution? How is it useful? Discuss.
(5)
14. How does selectivity of a resin relate with valence and nature of exchanging ions? Illustrate with suitable examples.
(5)
15. Discuss the separation of actinide elements using ion exchange chromatography.
(5)
16. Discuss the important characteristics of bio-gels.
(5)
17. Explain the preparative group preparations of size exclusion chromatography.
(5)
18. Describe salient features of nanofiltration.
(5)
19. Discuss the applications of membrane separations in the following areas: (i) Desalination and water treatment. (ii) Production of table salt.
(5)
20. Discuss the general features and operational aspects of capillary electrophoresis.
(5)
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TUTOR MARKED ASSIGNMENT MCH-003: Spectroscopic Methods Course Code: MCH-003 Assignment Code: MCH-003/TMA/2018 Maximum Marks: 100
Note: * *
1. a) b) c) d) 2. a) b)
c) 3. a) b) c) d) 4. a) b) c)
5.
a)
Answer all the questions given below. The marks are indicated in the brackets. Please answer these in your own words; answer copied from the course material will fetch poor marks.
What is a monochromatic radiation? Name the device used for obtaining a monochromatic radiation from polychromatic radiation.
(2)
Calculate the population of an energy level having energy of 200 kJ relative to the ground state in a molecule at 527oC.
(3)
State the necessary condition for a molecule to show i) a rotation spectrum and ii) a vibrational spectrum.
(2)
The visible spectra for the lanthanide ions consist of narrow bands whereas for the transition metal ions, these are broad. Explain.
(3)
Can we use glass cuvettes while making electronic spectral measurements in the UV range? Give reasons.
(2)
A solution of benzene in hexane taken in a cuvette having a path length of 2.0 cm showed an absorbance of 0.048 at 256 nm. Determine the concentration of given benzene solution.
(4)
How can two absorbing species in a given solution be determined simultaneously? Describe the process with the help of a suitable example.
(4)
Give the relationship between the frequencies of the first two overtones and the fundamental vibration frequency.
(2)
Explain the origin the Stokes and anti Stokes lines in a Raman spectrum in terms of quantum theory.
(3)
How can IR spectrum be used to check the authenticity of an organic compound?
(2)
Explain the origin of fluorescence and phosphorescence spectra in terms of Jablonski diagram.
(3)
What is the requirement for the vibrational mode of a molecule to be Raman active? (2) The fluorescence emission occurs at longer wavelengths than the absorption. Explain with the help of an energy level diagram.
(4)
Draw the block diagram for the experimental set up for the fluorescence spectral measurement. In what way is it different from that for the absorption measurement?
(4)
Explain the principle of revolving can shutter system used for simultaneous measurement of fluorescence and phosphorescence
(5)
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b) 6. a) b) 7. a) b) 8. a)
b) 9. a)
What is meant by a flame? Illustrate with the help of a suitable diagrammatic representation the processes occurring when an analyte is put into a flame.
(5)
Explain the internal standard method as quantitative analysis methodology used in flame photometry.
(5)
List different methods for preparing sample for AAS and describe any one of them in details.
(5)
Describe the working of an Electrodeless Discharge Lamp (EDL).
(5)
Explain the principle of GFAAS and list its advantages over FAAS.
(5)
Describe the mechanisms of Stokes direct line fluorescence and resonance fluorescence. In what way are the measurements based on direct line fluorescence better than that based on resonance fluorescence?
(5)
What is meant by plasma? Give a list of the plasma sources employed for atomic emission spectroscopy and state the power sources in each one of them.
(5)
The emission intensities of a series of standard solutions of potassium measured at 404.3 nm were found to be as given below: Concentration of potassium standard (g/cm3)
0.0
5.0
10.0
20.0
30.0
Relative emission intensity ( arbitrary units)
0
124
253
486
732
Determine the concentration of an unknown sample that gave a relative emission intensity of 372 under similar experimental conditions
(4)
b)
What is meant by isotopic peaks in mass spectrum? What is their importance?
(3)
c)
The mass spectrum of butanoic acid (Molar mass= 88 g mol-1) gives a characteristic peak at m/z = 60. Justify the same.
(3)
What is meant by spin-spin coupling in NMR? Explain the splitting of a proton signal having 1, 2 and 3 equivalent neighbouring protons respectively.
(5)
10. a) b)
Deduce the structure of an organic compound having molecular formula as C3H6O) on the basis of the following spectral information. Mass : m/z = 58 (Molecular ion); m/z = 15 and m/z = 43 (base peak) NMR: A singlet at =2.2 ppm IR: A strong signal at 1700 cm-1 besides other signals.
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(5)
TUTOR MARKED ASSIGNMENT MCH-004: Electro Analytical and Other Methods Course Code: MCH-004 Assignment Code: MCH-004/TMA/2017 Maximum Marks: 100
Note:
* *
This assignment is based on the entire course. All questions are compulsory. Marks for the questions are shown within brackets on the right hand side. * Please answer in your own words; do not copy from the course material.
1.
Given the following reaction half reaction: Cd2+ + 2e Cd E = 0.403 V Pb2+ + 2ePb E = 0.126 V where [Cd2+] = 0.020 M and [Pb2+] = 0.200 M construct a galvanic cell using half cell reactions and find i)
Which half cell –reaction is the cathode?
ii)
Write the cell reaction.
(10)
iii) Calculate Ecell of this galvanic cell. iv) Calculate Ecell of this galvanic cell
2.
3.
4.
5. 6. 7.
8.
v)
Calculate equilibrium constant using Ecell potentials of this galvanic cell based on the construction of ions.
a)
Discuss the factors which limit the accuracy of pH measurements.
(5)
b)
How the conductance is varies with concentration? Explain with the help of suitable examples.
(5)
a)
At 298, the limited molar conductivity at infinite dilution of sodium benzoate, hydrochloric acid and sodium chloride are 8.24 103 S m2 mol1, 4.26 102 S m2 mol1 and 1.26 102 respectively. Calculate the limiting molar conductivity of aqueous benzoic acid.
(5)
b)
Taking a suitable example, discuss the design of a solid state membrane electrode.
(5)
a)
What is controlled potential electrolysis? Write its applications.
(5)
b)
A solution of Zn is electrolysed for 30 s using a current if 1.0 mA. Calculate the mass of Zn plated on the electrode for the electrochemical reaction: Zn2+ + 2e Zn
(5)
a)
Write special features of coulometric methods.
(5)
b)
Give comparison between coulmetric and volumetric titrations.
(5)
a)
Describe the alternating current methods in voltammetry.
(5)
b)
Give the advantages of amperometry.
(5)
a)
What are the advantages of DTA and DSC over TGA?
(5)
b)
An impure sample of CaC2O4H2O is analysed using TGA technique. TG (5) curve of the sample indicates the total mass change from 85 mg to 30.7 mg when this sample was heated upto 1173 K. calculate the purity of the sample.
a)
Distinguish between thermometric and classical titration. 7
(5)
9.
10.
b)
At 291 K, the conductivity of pure water is 4.3 106 S m1. Calculate the ionic product of pure water at 291 K. Hint: Consult Table 4.2 for the limiting ionic conductivity of H+ and OH ions.
(5)
a)
How do nuclear reactions differ from chemical reactions, discuss briefly.
(5)
b)
List the various types of detector commonly used in measurement of radioactivity. Discuss any one of them in detail.
(5)
a)
Describe the isotope dilution analysis.
(5)
b)
Discuss the methodology of radio immune essay and list its advantages.
(5)
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