Download GTU BE/B.Tech 2019 Winter 4th Sem New 2140406 Stoichiometry Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY

BE - SEMESTER- IV (New) EXAMINATION - WINTER 2019

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Subject Code: 2140406 Date: 12/12/2019

Subject Name: Stoichiometry

Time: 10:30 AM TO 01:00 PM Total Marks: 70

Instructions:

1. Attempt all questions.

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2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

Q1

1. Define: Ideal gas law, Raoult’s law, Henry’s law. [03]
2. The conductance of a fluid —flow system is defined as volumetric flow rate, referred to a pressure of one torr (133.322 Pa.). For an orifice, the conductance C can be computed from C=89.24 Av(T/M) Where A = area of opening.ft², T = Temperature, 'R, M = Molecular Weight. Convert the empirical equation into SI units. [04]

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3. The average molar mass of a flue gas sample is calculated by two different engineers. One engineer uses the correct molar mass of 28 for N₂ and determines the average molar mass to be 30.08, the other engineer using an incorrect value of 14, calculate the average molar mass to be 18.74. Calculate 1) the volume % of N₂ in the flue gases , and 1i) if the remaining components of the flue gases are CO₂ and O₂. [07]

Q2

1. Iron metal weighs 200 lb & occupies a volume of 117 lit. Find the density in gm/cm³. [03]
2. The diameter and height of a vertical cylindrical tank are 5 ft and 6 ft 6 inch respectively. It is full up to 75% height with carbon tetrachloride (CCl₄), the density of which is 1.6 kg/lit. Find the mass in kg. [04]
3. Cracked gas from a petroleum/refinery has the following composition by vol.; Methane 45%, Ethane 10%, Ethylene 25%, Propane 7%, Propylene 8%, n-Butane 5%. Find: a) Average molecular weight of the mixture, and b) the composition by wt%. [07]

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OR

1. An aqueous solution of K₂CO₃ is prepared by dissolving 43 kg K₂CO₃ in 100 kg water at 293 K Find the molarity, normality and molality of the solution. Take specific gravity of the solution as 1.3 . [07]

Q3

1. Discuss methods of solving material balance problems without chemical reaction. [03]
2. State recycling and bypassing operations with their importance in the process industries. [04]

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3. The waste acid from a nitrating process containing 20% HNO₃, 55% H₂SO₄ and 25% H₂O by weight is to be concentrated by addition of concentrated sulphuric acid containing 95% H₂SO₄ and concentrated nitric acid containing 90% HNO₃ to get desired mixed acid containing 26 % HNO₃; and 60% H₂SO₄. Calculate the quantities of waste acid and concentrated acids required for 1000 kg of desired acid. [07]

OR

1. Define : Conversion, yield, selectivity. [03]
2. Formaldehyde is produced from methanol catalytic reactor. The production rate of formaldehyde is 1000 kg/h. If conversion of methanol is 65%, calculate the required feed rate of methanol. [04]
3. A sample of formaldehyde solution is found to contain 40.2% formaldehyde. The analysis of the solution indicated that TOC and ThOD are 258.3 mg/lit and and 965.5 mg/lit respectively. Find the concentration of each of the compounds in the sample. [07]

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Q4

1. Define: 1) Standard Heat of Formation ii) Standard Heat of Combustion iii) Standard Heat of Reaction. [03]
2. Soyabeen seeds are extracted with n-hexane in batch extractors. The flaked seeds contain 18.6% oil, 69.0% solids and 12.4% moisture. At the end of the extraction process, de-oiled cake (DOC) analysis yields 0.8% oil, 87.7% solids and 11.5% moisture. Find the percentage recovery of oil. All percentages are by mass. [04]
3. In the Deacon process for manufacturing chlorine, HCl gas is oxidized with air. The reaction taking place is: 4HCl(g) + O₂(g) = 2H₂O(g) + 2Cl₂(g) If the air is used in excess of 30% of that theoretically required, and if the oxidation is 80% complete, calculate the composition by volume of dry gases leaving the reaction chamber. [07]

OR

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1. State Hess’s law of constant heat summation with example. [03]
2. Pure methane is heated from 303K to 523K at atmospheric pressure. Calculate the heat added per kmol methane, using data given. C_p = a + bT + cT² + dT³ where C_p° = Ideal gas heat capacity at 101.325 kPa, kJ/(kmol.K) and T = Absolute temperature, K

   Compound	a	b x 103	c x 106	d x 109
   Methane (CH4)	19.2494	52.1135	11.973	-11.3173

   [04]
3. A pilot plant reactor was charged with 50 kg naphthalene and 200 kg (98% by wt.) H₂SO₄. The reaction was carried out for 3 hours at 433 K. the reaction goes to near completion. The product distribution was found to be 18.6% monosulphonate naphthalene and 81.4% disulphonate naphthalene. Calculate: a) the quantities of monosulphonate (MSN) and disulphonate (DSN) products, and b) the complete analysis of product. [07]

Q5

1. Explain material balance of Extractor. [03]

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2. A heat exchanger for cooling a hot hydrocarbon liquid uses 10000 kg/hr of cooling water, which enters the exchanger.at 294K. the hot oil at the rate of 5000 kg/hr enters at 423K and leaves at 338K and has an average heat capacity of 2.51 KJ/(kg.K). Calculate the outlet temperature of water. [04]
3. Obtain an empirical equation for calculating the heat of reaction at any temperature T (in K) for the reaction’. CH₄(g) + C₂H₄(g) ? C₃H₈(g). Data: ?H°_R at 298 K = -82.66 kJ/mol, C_p = a+bT + cT² + dT³, J/kmol.K

   Component	a	b x 103	c x 106	d x 109
   CH4 (g)	19.2494	52.1135	11.973	-11.3173
   C2H4(g)	4.1261	155.0213	-81.5455	16.9755
   C3H8(g)	-4.2227	306.264	-158.6316	32.1455

OR

1. Explain material balance of Crystallizer. [03]
2. Define & explain following terms: 1) absolute humidity (H) 1i) % humidity 1i1) wet-bulb temp (WB) 1v) humid heat (Cs). [04]

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3. 10000 kg of an aq sol containing 29.6% by wt anhydrous Na₂SO₄ at 413 K is charged to the crystallizer. During the cooling, 5% of initial water is lost by evaporation. As a result, crystals of Na₂SO₄.H₂O crystallize out. If the mother liquor is found to contain 18.3 % (by wt) anhydrous Na2SO4. Cal the yield & the quantity of mother liquor. [07]

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