BT-101 Engineering Chemistry - Jun 2022 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDiscuss the lime soda process for softening of hard water.
   How to answer

   • Principle of lime-soda water softening
   • Hot and cold lime-soda processes
   • Chemical reactions involved with lime and soda
   • Advantages and disadvantages of the process
2. 7 Marks
   bDescribe the ion exchange process used for softening of water with neat diagram.
   How to answer

   • Principle of demineralization/ion exchange
   • Cation and anion exchange resin reactions
   • Process schematic diagram showing both columns
   • Regeneration reactions using acid and alkali
3. 7 Marks
   aExplain various units of hardness of water giving their relationship.
   How to answer

   • Definition of hardness expressed in terms of CaCO3 equivalent
   • Definitions of ppm, mg/L, °Clark, and °French
   • Mathematical relationship table connecting the four units: 1 ppm = 1 mg/L = 0.07 °Cl = 0.1 °Fr
4. 7 Marks
   bDiscuss method for determination of alkalinity in given water sample.
   How to answer

   • Principle of titration against standard acid using phenolphthalein and methyl orange indicators
   • Reactions occurring at phenolphthalein end-point (P) and methyl orange end-point (M)
   • Table/rules to determine types of alkalinity: OH-, CO3^2-, and HCO3-
5. 7 Marks
   aWhat is triple point? Explain water system with the help of neat phase diagram.
   How to answer

   • Definition of triple point ($0.0098\,^\circ\text{C}$ and $4.58\,\text{mm Hg}$ for water)
   • Neat pressure-temperature phase diagram of water system
   • Discussion of curves (sublimation, vaporization, melting), areas, and the triple point
   • Application of phase rule $F = C - P + 2$ to curves, areas, and triple point
6. 7 Marks
   bWrite a short note on i) Viscosity index ii) Flash point
   How to answer

   • Definition and significance of Viscosity Index (Pennsylvanian vs Gulf oils scale)
   • Definition and significance of Flash point in lubricating oils
   • Apparatus used for flash point determination (Pensky-Martens / Abel apparatus)
7. 7 Marks
   aWhat are living polymers? Give preparation, properties and uses of PVC.
   How to answer

   • Definition and characteristics of living polymers (absence of termination/chain transfer)
   • Preparation/polymerization reaction of PVC from vinyl chloride
   • Key physical/chemical properties of PVC
   • Major commercial and industrial uses of PVC
8. 7 Marks
   bWhat is Elastomers? Give the preparation and properties and uses of BUNA's.
   How to answer

   • Definition of elastomers and intermolecular forces
   • Chemical reaction for preparation of Buna-S (1,3-butadiene + styrene)
   • Properties and applications of Buna-S rubber
9. 7 Marks
   aWhat is oxidation corrosion? and how does it take place? Describe the mechanism of oxidation corrosion.
   How to answer

   • Definition of oxidation corrosion (dry corrosion by direct chemical attack)
   • Mechanism of oxide film formation at metal surface
   • Pilling-Bedworth rule: protective vs non-protective oxide films
   • Role of cation/anion diffusion across the oxide film
10. 7 Marks
    bExplain pitting corrosion and stress corrosion.
    How to answer

    • Definition and cause of pitting corrosion (localized attack due to breakdown of protective film)
    • Mechanism: small anodic pit and large cathodic surrounding area
    • Definition of stress corrosion cracking (SCC) due to combined tensile stress and corrosive environment
    • Examples of stress corrosion (caustic embrittlement, season cracking of brass)
11. 14 Marks
    What is Electronic spectroscopy? Discuss about electronic transitions and applications of U.V. Spectroscopy.
    How to answer

    • Definition of electronic spectroscopy and UV absorption principles
    • Types of electronic transitions: $\sigma \rightarrow \sigma^*$, $n \rightarrow \sigma^*$, $\pi \rightarrow \pi^*$, $n \rightarrow \pi^*$
    • Energy levels diagram of electronic transitions
    • Applications: detection of functional groups, conjugation, quantitative analysis
12. 14 Marks
    Write short notes on: i) Polarizability ii) Thin film lubricants and fluid film lubricants
    How to answer

    • Definition and physical significance of polarizability
    • Mechanism of fluid film (hydrodynamic) lubrication
    • Mechanism of thin film (boundary) lubrication
    • Key differences between hydrodynamic and boundary lubrication mechanisms
13. 14 Marks
    Write brief note on (Any two) i) Degree of freedom ii) Biodegradable polymers iii) Electron affinity iv) Vulcanization of rubber
    How to answer

    • Degree of freedom: definition and formula $F = C - P + 2$
    • Biodegradable polymers: definition, examples (PLA, PHBV), applications
    • Electron affinity: definition, periodic trends, factors influencing it
    • Vulcanization of rubber: heating raw rubber with sulfur to form cross-links, resulting improvements in properties