Andhra University 2007 B.E chemical process and calculations - Question Paper

II Year B.E./B.Tech Degree exam
CHEMICAL PROCESS computations

(Chemical Engineering)

Time: three hours Max.Marks: 75

ques. one is compulsory

ans any 4 from ques. two to 8

All ques. carry equal marks

1. a) Distinguish ranging from molarity, molality and normality

b) describe Dalton’s legal regulations and Amagat’s legal regulations.

c) Distinguish ranging from absolute humidity, relative humidity

and % saturation.

d) Draw the ternary diagram for a system when all the

three pairs are partially miscible and indicate different

regions.

e) describe heat of formation, heat of combustion, heat of

solution and heat of reaction.

2. The flue gas out of a burner at 8000C and high pressure 2.5

atmosphere has the subsequent composition by weight

N2= 65%, CO2= 15%, H20=12%, O2= 7% and the rest CO

obtain a. the composition by quantity

b. the density of gas mixture in g/L at exit temperature

and at NTP

c. Mole Fraction of the components

d. change in composition (by weight) when it is passed

through a moisture absorbing bed.

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3. The gas from a sulfur burner has the subsequent composition by

quantity :

SO3 - 0.8%; O2 - 12.2%; SO2 - 7.8%; N2 - 79.2%

a) compute the quantity of gases (m3) at 3160C and 1.02

kg/cm2 pressure formed per kg of sulfur burnt.

b) compute the percentage excess oxygen supplied for

the combustion above that needed for complete

oxidation to SO3?

4. 1 thousand kg of a solution containing 30% by weight of

sodium carbonate in water is cooled slowly to 200C. During

the cooling, 10% of the water originally current is evaporated.

The carbonate precipitated is crystals of Na2CO3, 10H2O. If

the solubility of anhydrous sodium carbonate at 200C is 21.5

gm/100 gms of water. What weight of Na2CO3, 10H2O

crystallizes out.

5. The waste acid from a nitrating process contains 21% HNO3,

55% H2SO4 and 24% H2O by weight. This acid is to be

concentrated to contain 28% HNO3 and 62% H2SO4 by the

addition of concentrated sulfuric acid containing 93% H2SO4

and concentrated nitric acid containing 90% HNO3. computed

the weight of waste and concentrated acids that must be

combined to make 1500 kg of the desired mixture.

6. a) An approximate formula for CP (cal/gmol 0K) of

gaseous HCI is CP = 6.6 ¸ 9.6 x 10-3 T.

compute the heat needed to raise the temperature of

one g.mole of gas from 100 to 2000C.

b) The subsequent enthalpy modifications are known from

experiments for the reaction provided beneath at 250C in

standard state. compute the standard heat of formation

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( 0)fHD of propylene gas. Heats of reaction provided in

kcal/g.mol

i) three six two three eight C H (g) + H (g)®CH (g) O 29.6

R DH =-

ii) three eight two 2 two C H (g)+5O (g)®3CO (g)+4H O(l) O 530.6

R DH =-

iii) 1

2 two 2 two H+ O (g)®HO(l) O 68.3

R DH =-

iv) two 2 C(graphite)+O (g)®CO (g) O 94.05

R DH =-

7. a) Write a note on theoretical flame temperature

b) In an experiment methane is burnt with theoretical

volume of air for complete combustion. Ibecause of

faulty construction and operation of the equipment, the

reaction does not go to completion. If the methane and

air are originally at 250C and the total products leave at

4000C. What percent of methane is burnt?

Date : Heat of combustion at 250C when water is in

gaseous sate is - 191760 cal per gm.mole of methane

burnt. Mean CP values in cal/g.mol) oC

O2= 7.4, N2 =7.09, CH4 = 10.88. CO2 = 10.48, H2O = 8.35

8. A solution of 45 mole % benzene, 40 mole % toluene and the

rest o-xylene is stored in a vessel at 1220C. What is the

minimum pressure for which the vessel must be designed?

What is the composition of the 1st vapor evolve evolved

from the vessel? Vapor pressures of benzene, toluene and oxylene

are 2400, 1050 and 400 mmHg respectively at 1220C.

Earning:   Approval pending.