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SPPU Chemical Engineering (Semester 3)
Process Calculations
December 2016
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1(a) A staturated solution of salicylic acid (HOC6H4COOH) is methanol contain 64 kg salicylic acid per 100 kg methanol at 298 K. Find the composition in (i) weight % and ii) mol e %.
4 M
1(b) A waste acid from a nitrating process contains 21% HNO3, 55% H2SO4 and 24% water by weight. This acid is concentrated to a mixture containing 28% HNO3, 62%H2SO2 by addition of sulfuric acid containing 93% H2SO4 and nitric acid containing 90% HNO3. Calculate the weight of spent acid, concentrated sulfric acid and concentrated nitric acid that must be combined to obtain 1000 kg of desired mixed acid.
8 M

2(a) A solution of sodium chloride in water contains 20% NaC1 (by weight) at 333 K. The density of the solution is 1.127 kg/L Find:
i) Molartiy
ii) Normality and
iii) Molality of the solution.
4 M
2(b) An aqueous solution of Na2CO3 contain 15% carbonate by weight. 80% of the carbonte recovered as Na2 CO3. 10H2O by evaporation of water and subsequent cooling to 278 K. The solubility of Na2CO3 at 278 K is 9.0% (by weight). On the basis of 100 kg of solution treated, determine the following:
i) The quantity of crystal formed
ii) The amount of water evaporated.
8 M

3(a) A feed containing 60 role % A, 30 mole % B and 10 mole % inerts enters a reactor. The product stream leaving the reactor if found to contain 2 mode % A. Reaction taking place is 2A+B→C. Find the percentage of original A getting converted to C.
6 M
3(b) The heat capacity of carbon dioxide is given by the following relation:
Cp=26.540+42.454×10-3-14.298T×10-6T2; where Cp is in kJ/kmol K and T is in K :
i) How much heat is required to heat 1 kg of CO 2 from 300 K to 1000 K?
ii) Obtain the relation expressing the heat capacity in keal/ kmol°C and tempreature in°C.
7 M

4(a) Ammonia is sythesized according to the following reaction:
$\frac{1}{2}N_2+\frac{3}{4}H_2\rightarrow NH_3$
$\Delta H_{298}^{0}=-46.191kJ.$ The specific heat of the components are represented by $C_{p}=\alpha +\beta T+\gamma T^2$, where Cp is in J/mol K and the constants α
β and γ are:
 Molecules α β γ N2 27.31 5.2335×10-3 -4.1868×10-9 H2 29.09 -8.347×10-4 2.0139×10-6 NH3 25.48 36.89×10-3 -6.305×10-6

Determine the heat reaction:
9 M
4(b) Describe the following terms:
i) Limiting reactant
ii) Excess reactant
iii) Percent excess
iv) Stoichiometric coefficient.
4 M

5(a) The reaction A→ 2B+C takes place in a catalytic reactor (refer fig.). The reactor effluent is sent to a seprator. The overall conversion of A is 95 %. The product stream from the separator consists of B,C and 0.5% of A entering the separator, while the recycle stream consists of the reminder of the unreacted A and 1% B entering the separator. Calculate the following:
1) The single pass conversion of A in the reactor
2) The molar ratio of recycle to feed
!mage
7 M
5(b) Write short notes on the following:
1) Dry bulb temperature
2) Wet bulb temperature
3) Dew point.
6 M

6(a) The gas mixture containing carbon disulphide vapour (CS2) at a temperature of 300 K ans pressure of 100 kPa has percentage saturation of 70. Calculate the temperature to which gas must be cooled at constant pressure so as to condenses 40% of CS2 present in it. Data Given:
Vapor pressure of CS2 at 300 K : 52.662 kPa
Vapor pressure of CS2 at 287 K : 31.997 kPa
Vapor pressure of CS2 at 288 K : 33.33 kPa.
8 M
6(b) Define realtive humidity and percentage humidity and derive a relation between them.
5 M

7(a) A furnace is fired with fuel oil. The orsat analysis of the flue gases (by volume ) is CO2 : 10.6%,
O2 : 6% N2 : 83.4%.Calculate the percentage excess air and find the C : H ratio in the fuel oil, assuming that the fuel does not contain nitrogen.
8 M
7(b) The gross calorific value of liquid acetone at 298 K is 1791.21 kJ/mol. Find its net calorific value using latent heat of water at 298 K.
4 M

8(a) Define: