JNTU
JNTU B.Tech II CHEMICAL PROCESS CALCULATIONS Previous Question Paper (October - 2020 - R18)
Answer any five questions. All questions carry equal marks.
Main
By electrolyzing a mixed brine a mixture of gases is obtained at the cathode having the following percentage composition by weight: Cl2 – 67, Br2 – 28, O2 - 5. Using the ideal gas law, calculate:
Composition of the gas by volume
Answer
To find the composition by volume, we first calculate the moles of each component in 100 g of the mixture. The molecular weights are Cl2 = 71, Br2 = 160, and O2 = 32.
- Moles of Cl2 = 67 / 71 = 0.9437 mol
- Moles of Br2 = 28 / 160 = 0.1750 mol
- Moles of O2 = 5 / 32 = 0.1563 mol
- Total moles = 0.9437 + 0.1750 + 0.1563 = 1.2750 mol
Volume percentage is equal to mole percentage:
- Cl2: (0.9437 / 1.2750) × 100 = 74.02%
- Br2: (0.1750 / 1.2750) × 100 = 13.73%
- O2: (0.1563 / 1.2750) × 100 = 12.25%
Density of the mixture in grams per litre at 250C and 740 mm of Hg pressure
Answer
Using the ideal gas law, density ρ = (P × Mavg) / (R × T). First, calculate the average molecular weight (Mavg) of the mixture:
Given conditions: P = 740 / 760 = 0.9737 atm, T = 25 + 273.15 = 298.15 K, R = 0.08206 L·atm/(mol·K).
Specific gravity of the mixture, (air = 1.0), Atomic weights: Cl=35.5, Br=80, O=16.
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A solution of sodium chloride in water contains 230 grams of NaCl per liter at 200C. The density of the solution at this temperature is 1.148 gm/cm3. Calculate the following:
Composition in weight percent
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Volumetric percent of water
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Composition in mole percent
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Molality
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Composition in atomic percent
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Explain about effect of temperature on vapour pressure.
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Write about molal humidity, relative and percentage saturation.
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Air at a temperature of 300C and a pressure of 100 k Pa has relative humidity of 80%.
Calculate the molal humidity of the air
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Calculate the molal humidity of the air if its temperature is reduced to 150C and the pressure increased to 200 kPa, condensing out some of the water.
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The spent acid from a nitrating process contains 33 % H2SO4, 36 % HNO3, and H2O by weight. This acid is to be strengthened by addition of concentrated sulfuric acid containing 95% H2SO4, and concentrated nitric acid containing 78% HNO3. The strengthened mixed acid is to contain 40 % H2SO4 and 43% HNO3. Calculate the quantities of spent and concentrated acids that should be mixed together to yield 1500 lb of the desired mixed acid.
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What is Kistyakowsky equation? How it is applied to estimate the enthalpy of non-polar liquids.
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How do you calculate theoretical flame and actual flame temperature? Explain.
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Calculate the standard heat of formation of n-butane (g) (C4H10) at 298K from a knowledge of standard heat of combustion. Data: ΔHC0298 of C(s) = -393.78 kJ/mol; H2(g) = -286.03 kJ/mol; C4H10(g) = -2880.44 kJ/mol
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Octane is burnt with 10% excess air. Calculate:
air/fuel ratio by weight
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air/fuel ratio by volume
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Weight of dry exhaust gas formed per unit of fuel. The specific gravity of octane may be taken as 0.7.
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