Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Summer 4th Sem New 2140406 Stoichiometry Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?IV(NEW) ? EXAMINATION ? SUMMER 2019
Subject Code:2140406 Date:15/05/2019
Subject Name: Stoichiometry
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 (a) In a double effect evaporator plant, the second effect is maintained under
vacuum of 475 torr (mm Hg). Find the absolute pressure in kPa, bar and psi.
03
(b) A solution of sodium chloride in water contains 30% NaCl (by mass) at 333K.
The density of the solution is 1.2 kg/L. Find the molarity, normality and
molality of the solution. Atomic mass: Na = 23, Cl = 35.5.
04
(c) Obtain an empirical equation for calculating the heat of reaction at any
temperature T (in K) for the reaction: CH4 (g) + C2H5(g) ? C3H8
Data: ?H
?
R at 298 K = -82660 J/mol ,C
?
P= a + bT + cT
2
+ dT
3
, J/(mol.K).
Component a b ? 10
3
c ? 10
6
d ? 10
9
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
07
Q.2 (a) A weight of 1.10 kg of carbon dioxide occupies a volume of 33 litre at 300 K.
Using the Van der Waals equation of state, calculate the pressure.
03
(b) 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
(c) A gas mixture has the following composition by volume.
Ethylene: 30.6%, Benzene: 24.5%, Oxygen: 1.3%, Methane: 15.5%, Ethane:
25.0%, Nitrogen: 3.1%. Find a) the average molecular weight of the gas
mixture, b) the composition by weight, and c) the density of the mixture in
kg/m
3
at STP.
07
OR
(c) In case of liquids, the local heat-transfer coefficient for long tubes and using
bulk-temperature properties is expressed by the empirical equation
0.33 0.8 0.67 0.2 0.47
0.023 /( )
p
h G k c D ? ?
where h = heat-transfer coefficient, Btu/(h.ft
2
.
0
F)
G = mass velocity of liquid, lb/(ft
2
.s)
cp = heat capacity, Btu/(lb.
0
F)
k = thermal conductivity, Btu/(h.ft.
0
F)
D = diameter of tube, ft and
?= viscosity of liquid, lb/(ft.s)
Is the given equation dimensionally consistent? If yes, convert the equation
into SI units.
07
Q.3 (a) Explain Material balance of Extractor. 03
(b) Define Ideal gas law, Raoult?s Law, Henry?s Law and Dalton?s Law. 04
(c) 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 N 2 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
i) the volume % of N2 in the flue gases, and ii) if the remaining components of
07
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?IV(NEW) ? EXAMINATION ? SUMMER 2019
Subject Code:2140406 Date:15/05/2019
Subject Name: Stoichiometry
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 (a) In a double effect evaporator plant, the second effect is maintained under
vacuum of 475 torr (mm Hg). Find the absolute pressure in kPa, bar and psi.
03
(b) A solution of sodium chloride in water contains 30% NaCl (by mass) at 333K.
The density of the solution is 1.2 kg/L. Find the molarity, normality and
molality of the solution. Atomic mass: Na = 23, Cl = 35.5.
04
(c) Obtain an empirical equation for calculating the heat of reaction at any
temperature T (in K) for the reaction: CH4 (g) + C2H5(g) ? C3H8
Data: ?H
?
R at 298 K = -82660 J/mol ,C
?
P= a + bT + cT
2
+ dT
3
, J/(mol.K).
Component a b ? 10
3
c ? 10
6
d ? 10
9
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
07
Q.2 (a) A weight of 1.10 kg of carbon dioxide occupies a volume of 33 litre at 300 K.
Using the Van der Waals equation of state, calculate the pressure.
03
(b) 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
(c) A gas mixture has the following composition by volume.
Ethylene: 30.6%, Benzene: 24.5%, Oxygen: 1.3%, Methane: 15.5%, Ethane:
25.0%, Nitrogen: 3.1%. Find a) the average molecular weight of the gas
mixture, b) the composition by weight, and c) the density of the mixture in
kg/m
3
at STP.
07
OR
(c) In case of liquids, the local heat-transfer coefficient for long tubes and using
bulk-temperature properties is expressed by the empirical equation
0.33 0.8 0.67 0.2 0.47
0.023 /( )
p
h G k c D ? ?
where h = heat-transfer coefficient, Btu/(h.ft
2
.
0
F)
G = mass velocity of liquid, lb/(ft
2
.s)
cp = heat capacity, Btu/(lb.
0
F)
k = thermal conductivity, Btu/(h.ft.
0
F)
D = diameter of tube, ft and
?= viscosity of liquid, lb/(ft.s)
Is the given equation dimensionally consistent? If yes, convert the equation
into SI units.
07
Q.3 (a) Explain Material balance of Extractor. 03
(b) Define Ideal gas law, Raoult?s Law, Henry?s Law and Dalton?s Law. 04
(c) 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 N 2 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
i) the volume % of N2 in the flue gases, and ii) if the remaining components of
07
2
the flue gases are CO2 and O2, calculate the volume % of each of them.
OR
Q.3 (a) Discuss methods of solving material balance problems without chemical
reaction.
03
(b) A single effect evaporator is fed with 1000 kg/h of weak liquor containing
15% caustic by weight and is concentrated to get thick liquor containing 40%
by weight caustic (NaOH). Calculate: a) kg/h of water evaporated, and b) kg/h
of thick liquor obtained
04
(c) Heat capacity for gaseous SO2 is given by the following equation:
Cp = 43.458 + 10.634 ? 10
-3
T ? . Calculate the heat required to
raise the temperature of 1 kmol pure SO2 from 300 K to 1000 K.
07
Q.4 (a) Explain Material balance of Crystallizer. 03
(b) Define & explain following terms: i) absolute humidity (H) ii) % humidity iii)
wet-bulb temp (WB) iv) humid heat.
04
(c) 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
Q.4 (a) State Hess?s Law of constant heat summation with example. 03
(b) With a near sketch show the material balance for the following unit
operations: Distillation and Evaporation.
04
(c) A solution of ethyl alcohol containing 8.6% alcohol is fed at rate of 1000 kg/h
to a continuous distillation column. The product is a solution containing
95.5% alcohol. The waste solution from the column carries 0.1% alcohol. All
% are by weight. Calculate i) the mass flow rate of top & bottom product in
kg/h ii) the % loss of alcohol.
07
Q.5 (a) Define: (i) Standard Heat of formation (ii) Standard Heat of combustion (iii)
Standard Heat of reaction.
03
(b) Write a short note on recycling and bypassing operations. 04
(c) A pilot plant reactor was charged with 50 kg naphthalene and 200 kg (98% by
mass) H2SO4. The reaction was carried out for 3 hours at 433 K. The reaction
goes near to completion. The product distribution was found to be 18.6%
monosulphonate naphthalene and 81.4% disulphonate naphthalene. Calculate
(a) the quantities of monosulphonate naphthalene (MSN) and disulphonate
naphthalene (DSN) products, and (b) the complete analysis of the product.
07
OR
Q.5 (a) Define Conversion, Yield, and Selectivity. 03
(b) For o-xylene, calculate (a) latent heatof vaporization at TB using Riedel
equation, and (b) latent heat of vaporization at 25
0
C using Watson equation.
Data given: For o-xylene: Pc = 3732 kPa, Tc = 630.3 K, TB = 417.6 K
04
(c) In the Deacon process for manufacture of Chlorine, hydrochloric gas is
oxidized with air. The reaction taking place is:4 HCl + O2 ? 2 Cl2 + 2 H2O.
The air used is in excess of 30% of that theoretically required and the
oxidation is 80% complete. Calculate the composition by volume of dry gases
leaving the reaction chamber.
07
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This post was last modified on 20 February 2020