JNTU
JNTU B.Tech II CHEMICAL PROCESS CALCULATIONS Previous Question Paper (September - 2021 - R13)
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What is ideal gas? How do you apply ideal gas law to gaseous mixtures?
Answer
An ideal gas is a theoretical gas composed of particles that occupy negligible volume, exert no intermolecular forces, and undergo perfectly elastic collisions. It obeys the ideal gas law equation of state under all conditions of temperature and pressure.
For gaseous mixtures, the ideal gas law is applied using the concept of partial pressure (Dalton's Law) or partial volume (Amagat's Law). According to Dalton's Law, the total pressure of a mixture is the sum of the partial pressures exerted by each component if it occupied the total volume alone at the mixture temperature:
Where y_i is the mole fraction of component i. Each component in the mixture behaves as if it were an ideal gas in the total volume V, such that P_i V = n_i R T. Summing these for all components yields the total pressure relationship P_total V = n_total R T, where n_total is the sum of moles of all components.
Calculate the weight of 100 cu ft of water vapor, measured at a pressure of 15.5 mm Hg and 23°C.
Answer
To calculate the weight of the water vapor, use the ideal gas law in the form:
Given data:
- V = 100 cu ft = 2831.68 liters
- P = 15.5 mm Hg = 15.5 / 760 atm = 0.02039 atm
- T = 23°C = 296.15 K
- R = 0.08206 (L atm) / (mol K)
Calculate the number of moles (n):
The molecular weight of water (H₂O) is 18.015 g/mol. The weight (w) is:
Converting to pounds (1 lb = 453.59 g):
Calculate the volume occupied by 1 gm mole of water vapour at 900°C and 100 atm by the perfect gas law.
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Air contains 21% O2 and 79% N2 by volume. Calculate the composition in terms of percent by weight and its density at a pressure of 735.56 mm Hg and a temperature of 25°C. Assume air to behave as an ideal gas.
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Write short notes on the following:
Vapour pressure of immiscible liquids
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Critical properties estimation.
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Write short notes on the following: i) Liquefaction ii) Antoine equation.
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A mixture of ethanol vapour and air contains 5% ethanol by volume. Calculate the relative saturation and % saturation of the mixture at a temperature of 26°C and a pressure of 100 kPa.
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A producer gas made from coke has the following composition by volume: CO- 28%, CO2 - 3.5%, O2 - 0.5%, N2 - 68%. This gas is burned with such a quantity of air that the oxygen from the air is 20% in excess of the net oxygen required for complete combustion. If the combustion is 98% complete, Calculate the weight and composition in volumetric percent of the gaseous products formed per 100 kg of gas burned.
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A coal containing 87% total carbon and 7% unoxidized hydrogen is burned in air.
If air is used 40% in excess of that theoretically requires, calculate the number of pounds of air used per pound of coal burned.
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Calculate the composition, by weight, of the gases leaving the furnace, assuming complete combustion.
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Calculate the standard enthalpy change of the following reaction at 298 K:
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A producer gas with the composition by volume, 27.3% CO, 5.4% CO2, 0.6% O2, 66.7% N2 is burnt with 20% excess air. If the combustion is 98% complete, calculate the composition by volume of the flue gases.
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