JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Tech II Year CHEMICAL PROCESS CALCULATIONS Previous Question Paper (April/May - 2023 - R18)

B. Tech | II Year | I Semester | R18 | April/May - 2023

Answer PaperPaper Code: 153AFMaximum Marks: 75Time: 3 Hours

Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. iii) In Part B, Answer any one question from each unit.

Part A

1a

Define Gram-atoms of an elementary substance.

2 marks

Answer

The gram-atom (also referred to as a mole of atoms) of an elementary substance is defined as the quantity of that element whose mass in grams is numerically equal to its atomic weight (or relative atomic mass). Mathematically, it is expressed as:

Gram-atoms = Mass of the element in grams / Atomic weight of the element

For example, since the atomic weight of carbon is 12.01, one gram-atom of carbon corresponds to exactly 12.01 grams of the substance. This unit is fundamental in chemical process calculations as it represents 6.022 × 1023 atoms (Avogadro's number) of the element.

1b

An aqueous solution contains 40% Na2CO3 by weight. Express the composition in mole percent. Molecular weight of Na2CO3 = 106.

3 marks

Answer

To convert the weight percentage composition of an aqueous solution to mole percent, we consider a basis of 100 g of the solution.

  • Mass of Na2CO3 = 40 g
  • Mass of H2O = 100 g - 40 g = 60 g
  • Molecular weight of Na2CO3 (M1) = 106 g/mol
  • Molecular weight of H2O (M2) = 18 g/mol

Next, calculate the number of moles for each component:

  • Moles of Na2CO3 (n1) = 40 g / 106 g/mol = 0.3774 mol
  • Moles of H2O (n2) = 60 g / 18 g/mol = 3.3333 mol
  • Total moles (ntotal) = 0.3774 + 3.3333 = 3.7107 mol

Finally, calculate the mole percent of Na2CO3:

Mole fraction (x1) = n1 / ntotal = 0.3774 / 3.7107 = 0.1017

Mole percent of Na2CO3 = 0.1017 × 100 = 10.17%

1c

Define molal humidity and relative humidity of gas.

2 marks

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1d

State Antoine equation. Mention the applications of this equation.

3 marks

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1e

What is a recycle stream? Mention the purpose of recycling in a process?

2 marks

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1f

Explain limiting reactant and excess reactants with examples.

3 marks

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1g

State Trouton’s rule.

2 marks

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1h

What is theoretical flame temperature and actual flame temperature?

3 marks

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1i

Define fuel ratio of a coal.

2 marks

Answer

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1j

State and explain Dulong's formula for calculating heating value of a coal.

3 marks

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Part B

210 marks
a
A solution of naphthalene (C10H8), in benzene (C6H6) contains 25 mole per cent of naphthalene. Express the composition of the solution in weight percent. Atomic mass of C = 12 and H = 1.
4 marks

Answer

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b
A natural gas has the following composition, all figures being in volumetric per cent: CH4 = 86.5%, C2H6 = 11.7% and N2 = 1.8%. Calculate the composition in mole percent, average molecular weight and density of gas mixture at standard conditions. Atomic mass are: C = 12, H = 1 and N = 14.
6 marks

Answer

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OR
310 marks
a
A solution of potassium chloride in water contains 250 grams of KCl per liter at 20°C. The density of the solution at this temperature is 1.148 gm/cc. Calculate the following items: volumetric percent of water, composition in atomic percent and the molality. Atomic mass of K = 39 and for Cl = 35.
7 marks

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b
Define density and specific gravity of a gas.
3 marks

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410 marks
a
Describe the conditions for the boiling of bulk liquid.
4 marks

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b
Discuss the effects of temperature on vapor pressure of liquid.
4 marks

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c
What is Cox vapor – pressure chart?
2 marks

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OR
510 marks
a
State Raoult’s law. Explain the conditions for Raoult’s law validity from kinetic theory of equilibrium vapor pressures.
5 marks

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b
A mixture of acetone vapor and nitrogen contains 14.8% acetone by volume. Calculate the relative saturation and the percentage saturation of the mixture at a temperature of 200C and a pressure of 745 mm of Hg. The vapor pressure of acetone at 200C is 184.8 mm of Hg.
5 marks

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6

A solution of sodium nitrate in water at a temperature of 400C contains 49% of NaNO3 by weight. (a) Calculate the percentage saturation of this solution (b) Calculate the weight of NaNO3 that may crystallize out from 1000 kg of this solution by reducing the temperature to 100C. (c) Calculate the percentage yield. Data: Solubility of NaNO3 at 100C is 44.5 % by weight and at 400C is 51.5% by weight. Molecular mass of NaNO3 = 85 gm/mol.

10 marks

Answer

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OR
710 marks
a
Explain the two classes of material balance equations for processes involving chemical reactions.
5 marks

Answer

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b
Explain the material balance equations for a continuous drying operation.
5 marks

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810 marks
a
Explain the heat capacity of gas at constant volume (CV) and at constant pressure (CP). How are they related?
5 marks

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b
Discuss the Kirchhoff's equation to analyze the effect of temperature on heat of reaction.
5 marks

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OR
910 marks
a
Explain the calculation for heat of combustion and heat of neutralization with an example.
5 marks

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b
Compute the heat of reaction at 5000C for the combustion of SO2 according to the reaction. SO2 + 0.5 O2 → SO3.
5 marks

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1010 marks
a
Explain the physical meaning of hot thermal efficiency and cold thermal efficiency of a process.
5 marks

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b
Explain the input and output variables for the material balance equation of a coal combusting furnace.
5 marks

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OR
11

A coal containing C = 67.9%, H = 4.4%, S = 0.8%, N = 16%, O = 3.5%, ash = 4.5% and water = 2.9% is burnt in a furnace. The product of combustion (dry gas) analysis give the composition CO2 = 14.5%, O2 = 4.7% and N2 rest. Calculate (a) the theoretical volume of air used for the complete combustion of 100 kg of coal and (b) % excess air.

10 marks

Answer

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About this paper

This page contains the solved question paper with answers of CHEMICAL PROCESS CALCULATIONS from JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD for B. Tech PTM II Year I Semester, April/May - 2023, R18.

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