MCH-025 Solved Assignment January 2026 | Electroanalytical and other Analytical Methods | IGNOU MSCCHEM

Q: Explain why neutron induced reactions are most common whereas deuteron induced reactions require accelerator facility to carry out these reactions.

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Q1. Attempt all questions. The marks for each question are indicated against it.

(a)) Give a difference between: (200 words)
(i)) oxidation and oxidizing agent (50 words)
(ii)) reduction and reducing agent (50 words)
(iii)) a galvanic cell and an electrolytic cell (50 words)
(iv)) voltammetry and polarography (50 words)
(b)) Consider the following electrochemical cell Fe, Fe2+(0.1M) | Cd2+ (0.001M), Cd (200 words)
(i)) Write the cell reaction. (100 words)
(ii)) Calculate the EMF of the cell. Where, E°Cd2+/Cd = -0.40V and E°Fe2+/Fe = -0.44V (100 words)

Key Points:

Oxidation is electron loss; an oxidizing agent causes oxidation and gets reduced.
Reduction is electron gain; a reducing agent causes reduction and gets oxidized.
Galvanic cells produce electricity spontaneously, while electrolytic cells consume electricity for non-spontaneous reactions.
Voltammetry is a current-potential technique; polarography is a specific type using a dropping mercury electrode.

Answer: Electroanalytical methods are fundamental in chemistry, allowing for the study of chemical species and reactions through their electrical properties. This includes understanding core redox processes, the functioning of electrochemical cells, and specialized techniques like voltammetry. **(a) Differences between key electrochemical concepts:** **(i) Oxidation and Oxidizing Agent** Oxidation is a chemical process involving the loss of one or more electrons by a chemical species, resulting in an ...

Q2. What is Coulometer? Explain briefly. Write cathodic and anodic reaction of hydrogen-nitrogen coulometer, where 0.1 M hydrazine sulphate is used as the electrolyte.

(a)) What is Coulometer? Explain briefly. Write cathodic and anodic reaction of hydrogen-nitrogen coulometer, where 0.1 M hydrazine sulphate is used as the electrolyte. (200 words)
(b)) In a coulometric method, 200 mg of nitrobenzene in 100 cm³ of methanol is reduced to phenyl hydroxylamine at a constant potential of -0.95 V (vs. SCE) applied to an Hg electrode. Following reaction takes 30 minutes to complete. C6H5NO2 + 4H + + 4e- → C6H5NHOH + H2O Calculate the percentage of nitrobenzene if this reduction requires 32°C current. (200 words)

Key Points:

Coulometer measures quantity of electricity (charge) based on Faraday's laws.
Hydrogen-nitrogen coulometer uses hydrazine sulphate electrolyte.
Anodic reaction (H₂-N₂ coulometer): N₂H₄ → N₂ + 4H⁺ + 4e⁻ (hydrazine to nitrogen gas).
Cathodic reaction (H₂-N₂ coulometer): 2H⁺ + 2e⁻ → H₂ (hydrogen ions to hydrogen gas).

Answer: Electroanalytical methods are crucial for quantitative analysis, and coulometry is a prominent technique within this field. Coulometry precisely measures the quantity of electricity (charge) passed during an electrochemical reaction. This measurement allows for the determination of the amount of substance reacted, leveraging Faraday's laws of electrolysis. Different types of coulometers exist, including gas coulometers, which measure the volume of gases produced.

Q3. What is dropping mercury electrode? Give its advantages.

(a)) What is dropping mercury electrode? Give its advantages. (200 words)
(b)) Indium and Cadmium ions in 0.1 M HCl give peaks at potentials -0.557 V and -0.597 V by differential pulse polarographic analysis. When a standard solution containing 0.4 ppm of indium is analysed, it gave peak current (in arbitrary units) corresponding to 100.25 at -0.557 V and 43.75 at -0.597 V. A standard solution containing 0.4 ppm of Cd gave 'ps 29.52 at -0.557 V and 64.8 at -0.597 V. What is the concentration of indium and cadmium in a sample if the peak current is 190 at -0.557 V and 120 at -0.597 V. (200 words)

Key Points:

Dropping Mercury Electrode (DME) is a polarographic indicator electrode with a continuously renewed mercury surface.
DME's fresh surface ensures high reproducibility and minimizes electrode fouling from reaction products.
Mercury's high hydrogen overpotential extends the cathodic potential range, allowing analysis of many reducible species.
Differential Pulse Polarography (DPP) quantifies analytes by measuring peak currents at specific potentials.

Answer: Electroanalytical methods are crucial for quantitative and qualitative analysis in chemistry, leveraging the interaction between an analyte and an electrode. The dropping mercury electrode (DME) is a fundamental component in polarography, a specific electroanalytical technique, due to its unique properties that enhance analytical performance. Its operation relies on a continuous renewal of the electrode surface, offering significant advantages for the determination of various ionic species. Dif...

Q4. What are amperometric titrations? Draw common types of curves obtained in amperometric titrations. What will be the shape of the curve in bioamperometry for the titration of iodine by thiosulphate?

Key Points:

Amperometric titrations measure current changes at constant potential during titration.
Endpoint is determined by plotting current vs. titrant volume and observing slope changes.
Type I curve: Electroactive analyte, non-electroactive titrant; current decreases then flattens.
Type II curve: Non-electroactive analyte, electroactive titrant; current flattens then increases.

Answer: Amperometric titrations represent an electroanalytical technique where the current flowing through an electrochemical cell is monitored as a function of the volume of titrant added. This method relies on applying a constant potential to an indicator electrode, typically a dropping mercury electrode or a rotating platinum electrode, ensuring that one or more species involved in the titration (analyte, titrant, or product) is electroactive and contributes to the measured limiting current. The fu...

Q4. What are amperometric titrations? Draw common types of curves obtained in amperometric titrations. What will be the shape of the curve in bioamperometry for the titration of iodine by thiosulphate? (5) What is common source of errors in thermogravimetric analysis (TGA)? A mixture of CaO and CaCO3 is analysed by TGA. The result indicates that mass of the sample decreases from 250.6 mg to 190.8 mg only between 600°C and 900°C. Calculate the percentage of calcium carbonate in the mixture. (5)

(a)) What are amperometric titrations? Draw common types of curves obtained in amperometric titrations. What will be the shape of the curve in bioamperometry for the titration of iodine by thiosulphate? (200 words)
(b)) What is common source of errors in thermogravimetric analysis (TGA)? A mixture of CaO and CaCO3 is analysed by TGA. The result indicates that mass of the sample decreases from 250.6 mg to 190.8 mg only between 600°C and 900°C. Calculate the percentage of calcium carbonate in the mixture. (200 words)

Key Points:

Amperometric titrations measure current changes at constant potential during titration.
Endpoint is determined by plotting current vs. titrant volume and observing slope changes.
Type I curve: Electroactive analyte, non-electroactive titrant; current decreases then flattens.
Type II curve: Non-electroactive analyte, electroactive titrant; current flattens then increases.

Q5. Explain how thermometric titrations are different than classical titrations. Discuss their advantages.

(a)) Explain how thermometric titrations are different than classical titrations. Discuss their advantages. (200 words)
(b)) What is the principle of differential scanning calorimetry (DSC)? Draw the schematic diagram of a DSC instrument. (200 words)

Key Points:

Thermometric titrations detect equivalence points by measuring solution temperature changes.
Classical titrations rely on visual indicators or electrochemical sensors for endpoint detection.
Thermometric titrations are versatile, applicable to various reactions (precipitation, redox) and turbid solutions.
Differential Scanning Calorimetry (DSC) measures differential heat flow between sample and reference.

Answer: Thermometric titrations offer a distinct approach to quantitative analysis compared to classical titration methods, primarily by utilizing thermal changes in a reaction rather than visual or electrochemical indicators. This difference expands their applicability significantly. Differential Scanning Calorimetry (DSC), on the other hand, is a powerful thermoanalytical technique that quantifies heat flow associated with physical and chemical changes in materials, providing insights into their therm...

Q6. How many α and β particles will be emitted in following successive decays. (i) 234U→→→ 210Po (ii) 231Th→→→ 211Pb (iii) 233U → → → 213Bi (iv) 224Ra→ → → 208Ti

(a)) How many α and β particles will be emitted in following successive decays. (200 words)
(i)) 234U→→→ 210Po (50 words)
(ii)) 231Th→→→ 211Pb (50 words)
(iii)) 233U → → → 213Bi (50 words)
(iv)) 224Ra→ → → 208Ti (50 words)
(b)) What are the common sources of neutron for neutron activation analysis (NAA)? What factors contribute to higher sensitivity in NAA? Briefly explain any one. (200 words)

Key Points:

Alpha decay (α) reduces mass number by 4 and atomic number by 2.
Beta-minus decay (β⁻) keeps mass number constant and increases atomic number by 1.
Nuclear reactors are the most common and powerful neutron sources for NAA.
High neutron flux in NAA increases sensitivity by enhancing radioisotope production.

Answer: The calculations for alpha (α) and beta (β) particles emitted during successive radioactive decays involve tracking the changes in mass number (A) and atomic number (Z). Alpha decay reduces A by 4 and Z by 2, while beta-minus (β⁻) decay leaves A unchanged and increases Z by 1. For Neutron Activation Analysis (NAA), common neutron sources like nuclear reactors are crucial for inducing radioactivity. High sensitivity in NAA is influenced by several factors, including the neutron flux, which direct...

Q7. Explain why neutron induced reactions are most common whereas deuteron induced reactions require accelerator facility to carry out these reactions.

(a)) Explain why neutron induced reactions are most common whereas deuteron induced reactions require accelerator facility to carry out these reactions. (200 words)
(b)) In an isotope dilution analysis experiment, 15 mg radiolabelled analyte with specific activity 0.57 µCi/mg was added. After equilibration and chemical separation 2.76 mg pure analyte having specific activity 0.019 µCi/mg was isolated. Calculate the amount of analyte in the sample. (200 words)

Key Points:

Neutrons are neutral, allowing easy nuclear penetration without Coulombic repulsion.
Deuterons are positively charged, requiring high kinetic energy to overcome Coulombic barrier.
Neutron reactions utilize thermal neutrons from nuclear reactors or portable sources.
Deuteron reactions necessitate expensive particle accelerators for high energy input.

Answer:

Q8. What is the difference between SEM and TEM? Write the advantages of TEM over SEM?

(a)) What is the difference between SEM and TEM? Write the advantages of TEM over SEM? (200 words)
(b)) Which components are used in the X-ray photoelectron spectroscopy (XPS) instrument? Briefly explain with a schematic diagram of XPS Instrumentation. (200 words)

Key Points:

SEM images surface morphology using scattered electrons; TEM images internal structure using transmitted electrons.
TEM offers significantly higher spatial resolution (atomic scale) and internal microstructure analysis compared to SEM.
TEM provides unique crystallographic information through electron diffraction patterns, unavailable from SEM.
XPS is a surface-sensitive technique analyzing elemental composition and chemical states using X-rays.

Answer: Electron microscopy techniques like SEM and TEM are fundamental for materials characterization, providing insights into surface morphology and internal structure, respectively. While both use electron beams, their operational principles and the information they yield differ significantly. X-ray Photoelectron Spectroscopy (XPS) complements these by providing surface elemental and chemical state analysis through the photoelectric effect. Understanding the distinct instrumentation and applications ...

Q9. What information does the energy dispersive spectroscopy (EDS) provide? Write any three applications of EDS.

(a)) What information does the energy dispersive spectroscopy (EDS) provide? Write any three applications of EDS. (200 words)
(b)) Briefly explain the basic principle of Auger Electron Spectroscopy (AES) with a suitable diagram. (200 words)

Key Points:

EDS identifies elements by characteristic X-ray energies emitted from samples.
EDS provides qualitative (which elements) and quantitative (how much) elemental composition.
EDS can generate elemental maps showing spatial distribution of elements.
AES utilizes the Auger effect for highly surface-sensitive elemental analysis.

Answer: Electroanalytical and other analytical methods, such as Energy Dispersive Spectroscopy (EDS) and Auger Electron Spectroscopy (AES), are crucial for characterizing materials by providing insights into their elemental composition and distribution. These techniques utilize fundamental interactions between incident radiation (electrons) and the sample to generate characteristic signals, which are then detected and analyzed. EDS primarily offers information about the elemental makeup and spatial dis...

Q10. Write the basic principle of Rutherford backscattering spectroscopy (RBS) also name the ions commonly used for primary beam in RBS.

(a)) Write the basic principle of Rutherford backscattering spectroscopy (RBS) also name the ions commonly used for primary beam in RBS. (200 words)
(b)) How does atomic force microscopy (AFM) work? Explain briefly with their applications. (200 words)

Key Points:

RBS uses high-energy ion scattering to determine elemental composition and depth profiles.
Energy of backscattered ions reveals target atom mass and its depth in the sample.
Helium ions (He⁺) and protons (H⁺) are common primary beam ions in RBS.
AFM images surface topography by measuring interatomic forces between tip and sample.

Answer: Rutherford Backscattering Spectroscopy (RBS) is a powerful, non-destructive analytical technique used to determine the elemental composition and depth profiles of thin films and materials. It relies on the elastic scattering of high-energy ions from the nuclei of atoms within a sample. Atomic Force Microscopy (AFM), on the other hand, is a scanning probe microscopy technique that provides high-resolution imaging of surfaces, revealing topography and various physical properties at the nanoscale.

MCH-025 Solved Assignment — January 2026 / July 2026

Electroanalytical and other Analytical Methods | IGNOU Master of Science in Chemistry Programme (MSCCHEM)

MCH-025—January 2026 / July 2026

Electroanalytical and other Analytical Methods

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MCH-025 Assignment Questions — January 2026

Q1. Attempt all questions. The marks for each question are indicated against it.

Q2. What is Coulometer? Explain briefly. Write cathodic and anodic reaction of hydrogen-nitrogen coulometer, where 0.1 M hydrazine sulphate is used as the electrolyte.

Q3. What is dropping mercury electrode? Give its advantages.

Q4. What are amperometric titrations? Draw common types of curves obtained in amperometric titrations. What will be the shape of the curve in bioamperometry for the titration of iodine by thiosulphate?

Q5. Explain how thermometric titrations are different than classical titrations. Discuss their advantages.

Q6. How many α and β particles will be emitted in following successive decays. (i) 234U→→→ 210Po (ii) 231Th→→→ 211Pb (iii) 233U → → → 213Bi (iv) 224Ra→ → → 208Ti

Q7. Explain why neutron induced reactions are most common whereas deuteron induced reactions require accelerator facility to carry out these reactions.

Q8. What is the difference between SEM and TEM? Write the advantages of TEM over SEM?

Q9. What information does the energy dispersive spectroscopy (EDS) provide? Write any three applications of EDS.

Q10. Write the basic principle of Rutherford backscattering spectroscopy (RBS) also name the ions commonly used for primary beam in RBS.