Applied Chemistry
- Write a short note on sandwich panel of structural composite write its applications. Sandwich panel (a structural composite) A sandwich panel has two thin, strong and stiff outer face sheets (skins) bonded to a thick, lightwe... 1
- Explain viscoelasticity property of polymer. Viscoelasticity is the property of polymers by which they show both elastic (solid-like) and viscous (liquid-like) behaviour when deformed.... 1
- In a polymer sample 30% molecules have a molecular mass 20,000, 40% have molecular mass 30,000 and the 30% have 60,000. Calculate the weight average, number average molecular weight and polydispersity of polymer sample. Given (number fractions of molecules): take 100 molecules, so N_i = 30, 40, 30. N_iM_iN_iM_iN_iM_i² 3020,0006.0 × 10⁵1.2 × 10¹⁰ 4030,00012.0... 1
- Give the definitions and significance of following properties of polymer. Tensile strength, insulation resistance and refractive index. 1. Tensile strength Definition: the maximum tensile (pulling) stress a polymer specimen can withstand before it breaks: tensile strength = m... 1
- Explain the terms involved in Gibbs phase rule with an example of a one-component system. (Phase, Component and Degree of Freedom) Gibbs phase rule: F = C − P + 2 Phase (P): a homogeneous, physically distinct and mechanically separable part of a heterogeneous system, sep... 1
- Write notes on (a) reduced phase rule (c) applications of phase diagram. (a) Reduced (condensed) phase rule The Gibbs phase rule is F = C − P + 2. In solid–liquid systems (alloys) the gas phase is absent or neglig... 1
- An alloy of Cd and Bi contains 25% Cd. Find the mass of eutectic in 1 kg of alloy if the system contains 40% Cd. Given: the alloy has 25% Cd (75% Bi). "The system contains 40% Cd" is taken to mean that the eutectic contains 40% Cd (60% Bi), as in the st... 1
- Explain the sacrificial anode cathodic protection method with a neat and well-labelled diagram. Cathodic protection: the metal to be protected is forced to act as the cathode of an electrochemical cell, so it does not corrode. Corrosion... 1
- How can material selection and design prevent corrosion? Explain which protective coatings can be used for corrosion prevention. 1. Proper selection of material Use noble or corrosion-resistant metals (Pt, Au, Ti) or alloys such as stainless steel and cupronickel where... 1
- Explain the rusting of iron with the help of the electrochemical theory of corrosion and a diagram. Electrochemical (wet) theory: when a metal is in contact with moisture or an electrolyte, many tiny galvanic cells form on its surface. The... 1
- Define calorific value and write the significance of proximate analysis of coal. Calorific value is the total quantity of heat liberated when a unit mass (or unit volume) of a fuel is burnt completely in air or oxygen. Un... 1
- How is the percentage of sulphur determined in a solid fuel? Principle: the sulphur in the solid fuel is converted to sulphate, precipitated as BaSO₄ and weighed. A known mass (W g) of the fuel is burn... 1
- Calculate the gross and net calorific value of coal having the following compositions. Carbon=85%, hydrogen=8%, sulphur=1%, nitrogen=2%, ash=4%, and the latent heat of steam is 587 cal/gm. Given: C = 85%, H = 8%, S = 1%, N = 2%, ash = 4%. Total = 85 + 8 + 1 + 2 + 4 = 100%, so O = 0%. Latent heat of steam = 587 cal/g = 587 kcal/... 1
- 1.0 g of coal sample was digested (Kjeldahl method). The liberated ammonia was absorbed in 25 ml of N/10 H2SO4. To neutralise excess acid, 15 ml of 0.1 N NaOH was required. Determine the % nitrogen in the given sample of coal. Kjeldahl method: coal is digested with conc. H₂SO₄ + K₂SO₄ (with a CuSO₄ catalyst), which converts N to (NH₄)₂SO₄. Heating with NaOH liberat... 1
- Discuss super critical solvents with its applications. A supercritical fluid (SCF) is a substance held above its critical temperature (T_c) and critical pressure (P_c). There it exists as a singl... 1
- Write the conventional and green methods for the synthesis of adipic acid. Conventional (traditional) route C₆H₆ xrightarrow[Ni / Pt]3H₂ undersetcyclohexanemathrmC₆H₁₂ xrightarrow[Co catalyst]O₂\ (air) undersetcyclo... 1
- Write about the synthesis and advantages of biodiesel. Biodiesel is a mixture of mono-alkyl (methyl or ethyl) esters of long-chain fatty acids. It is made from vegetable oils (jatropha, karanja,... 1
- Discuss applications of composites. Composites combine high strength and stiffness with low weight and good corrosion resistance. Their main applications are: Aerospace: CFRP a... 1
- Classify composites with the help of a diagram and an example of each class. COMPOSITES ______________________|______________________ | | | Particle-reinforced Fibre-reinforced Structural ____|____ ____|_______ ____|_... 1
- Define matrix and dispersed phase with its functions and examples. A composite has two constituents: 1. Matrix phase – the continuous phase that surrounds and binds the other phase. It may be a polymer, meta... 1
- Define the tensile strength of a polymer and explain its significance. Tensile strength is the maximum tensile (stretching) stress that a polymer can withstand before it breaks (fractures): Tensile strength = ma... 1
- Explain all types of chemical bonds existing in polymers. Polymers contain primary (covalent) bonds along the chain and secondary (intermolecular) forces between chains. Together they decide the str... 1
- Write short notes on crystallinity, number average molecular weight and fatigue of polymers. 1. Crystallinity Polymers have crystalline regions, where chains are packed in an ordered, regular way (crystallites or lamellae formed by f... 1
- What is condensed phase rule equation? Explain its application with the help of phase diagram to two component lead-silver system. Condensed (reduced) phase rule: Gibbs' phase rule is F = C − P + 2. In solid–liquid systems such as alloys the vapour phase is negligible, a... 1