University Of Pune Question Paper
S.E. (Chemical) (Semester – I) Examination, 2011
PROCESS CALCULATIONS
(2003 Course) (Common to Biotech)
Time : 3 Hours Max. Marks : 100
Instructions : I) Answers to the two Sections should be written in
separate books.
II) Neat diagrams must be drawn wherever necessary.
III) Black figures to the right indicate full marks.
IV) Use of logarithmic tables, slide rule, Mollier charts,
electronic pocket calculator and steam tables is
allowed.
V) Assume suitable data, if necessary.
SECTION – I
1. a) The iron metal whose weight is 500 pounds occupies a volume 29.25 litres,
calculate the density of iron metal expressed in kg / m3. 4
b) Determine the weight percentage of the constituent elements of potassium
sulphate. 4
c) Carburetted water gas has the following composition by volume : Hydrogen
35.2 %, Methane 14.8 %, Ethylene 12.8 %, Carbon dioxide 1.5 %, Carbon
monoxide 33.9 % and Nitrogen 1.8 %. The gas is available at 101.3 kN / m2
and 300 K. Express the composition by wt % and determine the average
molecular weight and density of the gas. 8
OR
2. a) A compound is found to contain 62.4 % Ca and 37.6 % C.
i) How many gram atoms of Ca and C present in 100 gm of the compound ?
ii) Suggest an empirical formula for the compound. 6
b) Calculate the molality of a solution of 93 % H2SO4 (W/V). The density of
the solution is 1840 kg / m3. 5
c) A sample of limestone is found to contain 54.5 % CaO (by mass). If this
CaO is present as CaCO3 in the limestone, find the content of CaCO3 in the
limestone. 5
3. The feed to an absorption column consists of 20 % H2S and the balance inert.
Only H2S is removed from the gas by absorbing in an alkaline solution. The gas
enters the absorber at 600 kPa and 310 K and leaves at 500 kPa and 290 K
containing 2 % H2S. If H2S is removed at the rate of 100 kg / hr, calculate
i) the volume of gas (in m3) entering per hour, ii) the volume of gas (in m3)
leaving per hour, iii) percentage recovery of H2S. 16
OR
4. a) Crystals of MgCl2.6H2O have solubility of 190 gm per 100 gm ethanol at
298.15 K. It is desired to make 1000 kg of saturated solution. Calculate the
quantities of the crystals and ethanol required to make the above solution.
Also, find the composition of saturated solution by mass. 8
b) A mixture of CuSO4.5H2O and FeSO4.7H2O weighs 100 gm. It is heated in
an oven at 378 K to evaporate water of hydration. The mass of mixture after
removal of water is 59.78 gm. Calculate the mass ratio of CuSO4 to FeSO4
in the mixture. 8
5. Pure sulphur is burnt in a burner at the rate of 0.3 kg/sec. Fresh dry air is
supplied at 303 K and 100 kPa. The gases from the burner contain 16.5 % SO2,
3.5 % O2 and rest N2 on SO3 - free volume basis. The gases leave the burner at
1073 K and 101.3 kPa absolute. Calculate (a) the fraction of sulphur burnt into
SO3 (b) the percentage excess air over the amount required to oxidise the sulphur
to SO2 and (c) the volume of dry air in m3/sec. 18
OR
6. A mixture of pure carbon dioxide and hydrogen is passed over a nickel catalyst.
The temperature of the catalyst bed is 588 K and the reactor pressure is 2 MPa g.
The analysis of the gases leaving the reactor showed CO 57.1 %, H2 41.1 %,
CH4 1.68 % and CO 0.12 % (by volume) on a dry basis. The reactions taking
place in the reactor are :
CO2 + 4 H2 = CH4 + 2 H2O
and CO2 + H2 = CO + H2O
Find (a) the conversion of CO2 per pass (b) yield of CH4 in terms of CO2
reacted and (c) the composition of the feed. 18
SECTION – II
7. a) Heat capacity of gaseous SO2 is given by
0 Cmp = 43.458 + 10.634 × 10−3 T − 5.945 × 105 T −2 kJ / kmol.K
Calculate the heat required to raise the temperature of 1.0 kg pure SO2 from
300 to 1000 K. 8
b) In the ferrite process for the manufacture of caustic soda, soda ash and
gangue from pyrites roaster are mixed and heated. The following reaction
takes place and CO2 evolves. Calculate the standard heat of reaction at 298.15 K.
Na2CO3 (s) + Fe2O3 (s) = Na2O.Fe2O3 (s) + CO2 (g)
Given Data : Std Heat of formation at 298.15 K
Component H kJ / mol Δ f
1. Na2CO3 (s) − 1130.68
2. Fe2O3 (s) − 817.30
3. Na2O.Fe2O3 (s) − 1412.20
4. CO2 (g) − 393.51 8
OR
8. Oil is to be extracted from meal by a continuous counter-current extractor. The
unit is charged with 1000 kg/hr meal based on oil-free solids. Untreated meal
contains 0.4 kg oil and 0.025 kg benzene per kg oil-free meal. A fresh solvent is
benzene containing 1.5 % oil (mass %). The ratio of the fresh solvent to the oilfree
meal is kept at 0.065 kg/kg. The solid meal retains 0.507 kg solution per kg
solid. The solution retained by the meal contains 11.83 % oil (by mass). Make a
complete material balance and find the composition and the amount of overflow
from the extractor. 16
9. An air conditioning plant is employed to maintain 300 K DBT and 50 % RH in
an auditorium. The air flow rate to the auditorium is measured to be 5.806 m3 / sec
at 290 K at 83.5 % RH. The effluent air from auditorium is partially recycled and
is mixed with the incoming fresh air. The fresh air is fed at the rate of 1.25 m3 / sec
at 308 K having 70 % RH. The mixed air is found to have 302.5 K at DBT and
54 % RH and is passed through a/c plant to make it suitable for auditorium. The
total pressure can be assumed to be 101.3kPa.
Calculate :
a) Moisture added in auditorium / removed in a/c plant.
b) The recycle ratio.
c) Moles of air recycled per mole of fresh ambient air. 18
OR
10. a) A solution of ethyl alcohol containing 8.6 % alcohol is fed at the rate of
1000 kg / h to a continuous distillation column. The product (distillate) is a
solution containing 95.5 % alcohol. The waste solution from the column carries
0.1 % of alcohol. All percentages are by mass. Calculate the mass flow rates
of top
and bottom products in kg / h and the percentage loss of alcohol. 10
b) A crystallizer is charged with 7500 kg of an aqueous solution at 377 K, 29.6 %
by mass of which is anhydrous sodium sulphate. The solution is cooled.
During the cooling operation 5 % of the initial water is lost by evaporation.
As a result, crystals of Na2SO4.10 H2O crystallize out. If the mother liquor
is found to contain 18.3 % (by mass) anhydrous Na2SO4. Calculate the yield
of crystals and the quantity of mother liquor. 8
11. A coal sample from Godavari colliery has the following proximate and ultimate
analyses.
Proximate Analysis mass % Ultimate Analysis mass %
Moisture 7.0 Carbon 54.0
Volatile matter 26.0 Hydrogen 3.0
Fixed Carbon 46.0 Sulphur 0.4
Ash 21.0 Nitrogen 2.2
Ash 21.0
Oxygen (by diff) 19.4
The gross calorific value = 23392 kJ / kg at 298.15 K.
Calculate :
a) The net hydrogen in the coal,
b) The combined water in the coal,
c) GCV based on the Dulong formula, and
d) NCV of the coal. 16
OR
12. The purge gas obtained from ammonia synthesis loop has the composition
H2 – 69 %, N2 – 23 %, Ar – 2.7 %, and CH4 – 5.3 % (mole basis). It is burnt
with 20 % excess air. Calculate (a) the GCV and NCV at 298.15 K of the purge
gas, (b) theoretical air required, and (c) the molar composition of the flue gases.
GCV and NCV of CH4 is 890.65 and 802.62 kJ / mol respectively.
Latent heat of water vapour at 298.15 K = 2442.5 kJ / kg. 16
Atomic weights : Fe = 55.8, Ca = 40, Na = 23, K = 39, S = 32, Mg = 24, Cu = 63.5.
————————
S.E. (Chemical) (Semester – I) Examination, 2011
PROCESS CALCULATIONS
(2003 Course) (Common to Biotech)
Time : 3 Hours Max. Marks : 100
Instructions : I) Answers to the two Sections should be written in
separate books.
II) Neat diagrams must be drawn wherever necessary.
III) Black figures to the right indicate full marks.
IV) Use of logarithmic tables, slide rule, Mollier charts,
electronic pocket calculator and steam tables is
allowed.
V) Assume suitable data, if necessary.
SECTION – I
1. a) The iron metal whose weight is 500 pounds occupies a volume 29.25 litres,
calculate the density of iron metal expressed in kg / m3. 4
b) Determine the weight percentage of the constituent elements of potassium
sulphate. 4
c) Carburetted water gas has the following composition by volume : Hydrogen
35.2 %, Methane 14.8 %, Ethylene 12.8 %, Carbon dioxide 1.5 %, Carbon
monoxide 33.9 % and Nitrogen 1.8 %. The gas is available at 101.3 kN / m2
and 300 K. Express the composition by wt % and determine the average
molecular weight and density of the gas. 8
OR
2. a) A compound is found to contain 62.4 % Ca and 37.6 % C.
i) How many gram atoms of Ca and C present in 100 gm of the compound ?
ii) Suggest an empirical formula for the compound. 6
b) Calculate the molality of a solution of 93 % H2SO4 (W/V). The density of
the solution is 1840 kg / m3. 5
c) A sample of limestone is found to contain 54.5 % CaO (by mass). If this
CaO is present as CaCO3 in the limestone, find the content of CaCO3 in the
limestone. 5
3. The feed to an absorption column consists of 20 % H2S and the balance inert.
Only H2S is removed from the gas by absorbing in an alkaline solution. The gas
enters the absorber at 600 kPa and 310 K and leaves at 500 kPa and 290 K
containing 2 % H2S. If H2S is removed at the rate of 100 kg / hr, calculate
i) the volume of gas (in m3) entering per hour, ii) the volume of gas (in m3)
leaving per hour, iii) percentage recovery of H2S. 16
OR
4. a) Crystals of MgCl2.6H2O have solubility of 190 gm per 100 gm ethanol at
298.15 K. It is desired to make 1000 kg of saturated solution. Calculate the
quantities of the crystals and ethanol required to make the above solution.
Also, find the composition of saturated solution by mass. 8
b) A mixture of CuSO4.5H2O and FeSO4.7H2O weighs 100 gm. It is heated in
an oven at 378 K to evaporate water of hydration. The mass of mixture after
removal of water is 59.78 gm. Calculate the mass ratio of CuSO4 to FeSO4
in the mixture. 8
5. Pure sulphur is burnt in a burner at the rate of 0.3 kg/sec. Fresh dry air is
supplied at 303 K and 100 kPa. The gases from the burner contain 16.5 % SO2,
3.5 % O2 and rest N2 on SO3 - free volume basis. The gases leave the burner at
1073 K and 101.3 kPa absolute. Calculate (a) the fraction of sulphur burnt into
SO3 (b) the percentage excess air over the amount required to oxidise the sulphur
to SO2 and (c) the volume of dry air in m3/sec. 18
OR
6. A mixture of pure carbon dioxide and hydrogen is passed over a nickel catalyst.
The temperature of the catalyst bed is 588 K and the reactor pressure is 2 MPa g.
The analysis of the gases leaving the reactor showed CO 57.1 %, H2 41.1 %,
CH4 1.68 % and CO 0.12 % (by volume) on a dry basis. The reactions taking
place in the reactor are :
CO2 + 4 H2 = CH4 + 2 H2O
and CO2 + H2 = CO + H2O
Find (a) the conversion of CO2 per pass (b) yield of CH4 in terms of CO2
reacted and (c) the composition of the feed. 18
SECTION – II
7. a) Heat capacity of gaseous SO2 is given by
0 Cmp = 43.458 + 10.634 × 10−3 T − 5.945 × 105 T −2 kJ / kmol.K
Calculate the heat required to raise the temperature of 1.0 kg pure SO2 from
300 to 1000 K. 8
b) In the ferrite process for the manufacture of caustic soda, soda ash and
gangue from pyrites roaster are mixed and heated. The following reaction
takes place and CO2 evolves. Calculate the standard heat of reaction at 298.15 K.
Na2CO3 (s) + Fe2O3 (s) = Na2O.Fe2O3 (s) + CO2 (g)
Given Data : Std Heat of formation at 298.15 K
Component H kJ / mol Δ f
1. Na2CO3 (s) − 1130.68
2. Fe2O3 (s) − 817.30
3. Na2O.Fe2O3 (s) − 1412.20
4. CO2 (g) − 393.51 8
OR
8. Oil is to be extracted from meal by a continuous counter-current extractor. The
unit is charged with 1000 kg/hr meal based on oil-free solids. Untreated meal
contains 0.4 kg oil and 0.025 kg benzene per kg oil-free meal. A fresh solvent is
benzene containing 1.5 % oil (mass %). The ratio of the fresh solvent to the oilfree
meal is kept at 0.065 kg/kg. The solid meal retains 0.507 kg solution per kg
solid. The solution retained by the meal contains 11.83 % oil (by mass). Make a
complete material balance and find the composition and the amount of overflow
from the extractor. 16
9. An air conditioning plant is employed to maintain 300 K DBT and 50 % RH in
an auditorium. The air flow rate to the auditorium is measured to be 5.806 m3 / sec
at 290 K at 83.5 % RH. The effluent air from auditorium is partially recycled and
is mixed with the incoming fresh air. The fresh air is fed at the rate of 1.25 m3 / sec
at 308 K having 70 % RH. The mixed air is found to have 302.5 K at DBT and
54 % RH and is passed through a/c plant to make it suitable for auditorium. The
total pressure can be assumed to be 101.3kPa.
Calculate :
a) Moisture added in auditorium / removed in a/c plant.
b) The recycle ratio.
c) Moles of air recycled per mole of fresh ambient air. 18
OR
10. a) A solution of ethyl alcohol containing 8.6 % alcohol is fed at the rate of
1000 kg / h to a continuous distillation column. The product (distillate) is a
solution containing 95.5 % alcohol. The waste solution from the column carries
0.1 % of alcohol. All percentages are by mass. Calculate the mass flow rates
of top
and bottom products in kg / h and the percentage loss of alcohol. 10
b) A crystallizer is charged with 7500 kg of an aqueous solution at 377 K, 29.6 %
by mass of which is anhydrous sodium sulphate. The solution is cooled.
During the cooling operation 5 % of the initial water is lost by evaporation.
As a result, crystals of Na2SO4.10 H2O crystallize out. If the mother liquor
is found to contain 18.3 % (by mass) anhydrous Na2SO4. Calculate the yield
of crystals and the quantity of mother liquor. 8
11. A coal sample from Godavari colliery has the following proximate and ultimate
analyses.
Proximate Analysis mass % Ultimate Analysis mass %
Moisture 7.0 Carbon 54.0
Volatile matter 26.0 Hydrogen 3.0
Fixed Carbon 46.0 Sulphur 0.4
Ash 21.0 Nitrogen 2.2
Ash 21.0
Oxygen (by diff) 19.4
The gross calorific value = 23392 kJ / kg at 298.15 K.
Calculate :
a) The net hydrogen in the coal,
b) The combined water in the coal,
c) GCV based on the Dulong formula, and
d) NCV of the coal. 16
OR
12. The purge gas obtained from ammonia synthesis loop has the composition
H2 – 69 %, N2 – 23 %, Ar – 2.7 %, and CH4 – 5.3 % (mole basis). It is burnt
with 20 % excess air. Calculate (a) the GCV and NCV at 298.15 K of the purge
gas, (b) theoretical air required, and (c) the molar composition of the flue gases.
GCV and NCV of CH4 is 890.65 and 802.62 kJ / mol respectively.
Latent heat of water vapour at 298.15 K = 2442.5 kJ / kg. 16
Atomic weights : Fe = 55.8, Ca = 40, Na = 23, K = 39, S = 32, Mg = 24, Cu = 63.5.
————————
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