JNTU II B.Tech I Semester Regular Examinations, November 2008
CHEMICAL PROCESS CALCULATIONS
1. How many kilograms of CO2 are obtained by the decomposition of 100 kg of lime stone containing 94.5% CaCO3, 4.2% MgCO3, and 1.3% inert material? What is the volume of CO2 obtained at STP?
2. (a) A 50 m diameter spherical balloon contains air at 300 K and 1 bar. How many
kilograms of air present in the balloon. Take the molecular weight of air to be 29.
(b) 20 kg of Cl2 is to be stored on a container at 0.9 bar and 295 K. What should be the volume of the container?
3. The vapor pressure (P*) of Chloroform is given by the Antoine Equation ln P_ = 13.9582 ?2696.79 / T?46.16
Where pressure in kpa and temperature in K. Determine:
(a) The boiling point of Chloroform at 50 kpa
(b) The vapor pressure at 300 K.
4. A stream of air at 30 0C and 10% relative humidity is humidified in an adiabatic
spray tower operating at 1 atm. The emerging air is to have a relative humidity of 40%. Use humidity chart to calculate the rate at which water must be added to humidify 1000 kg/h of entering air.
5. In the hydrochloric acid manufacture, the reactants sodium chloride and sulfuric acid are heated in a reactor. The hydrochloric acid gas obtained is absorbed in water to produce 30% HCl by weight. Some HCl is lost in absorption. To produce 1000 kg of 30% HCl, the reactor is charged with 560 kg of NaCl and 500 kg of 97% H2SO4. The reaction is 100% complete. Calculate:
(a) Percentage loss of HCl during absorption
(b) Weight and composition of residue in the reactor assuming 48% water has gone out as vapor.
6. A material containg 70% water and 30% solid is fed to a granulator at a rate of 3000 kg/hr. The feed is premixed in the granulator with recycled product from a drier which follows the granulator to reduce the water concentration of the overall material in the granulator to 50% water and 50% solid. The product leaves the drier is 16% water. In the drier, air is passed over the solid being dried. In the drier, air is passed over the solid being dried. The air entering the drier contains 3% water by weight and the air leaving drier contains 6% water by weight.
(a) What is the recycle rate to the granulator?
(b) What is the rate of air flow to the drier on a dry basis?
7. 2500 kcal of heat are added to 8 mol of the gaseous mixture having the following composition by volume: CO2 = 70%, N2 = 27% and O2 = 3%. The gas mixture is initially at 300C. What is the final temperature of the gas mixture?
Cp for CO2 = 6.339 + 10.14 × 10?3T ? 3.415 × 10?6 T2
Cp for N2 = 6.457 + 1.389 × 10?3 T ? 0.069 × 10?6 T2
Cp for O2 = 6.117 + 3.167 × 10?3 T ? 1.005 × 10?6 T2
Here Cp is in Cal/(mol.K) and T is in K.
8. (a) What are standard heat of formation and standard heat of combustion? How can you obtain standard heat of reaction from standard heat of formation and standard heat of combustion?
(b) For the following reaction calculate the standard heat of reaction:
C2H5OH(l) + CH3COOH(l) ! C2H5OOCCH3(l) + H2O(l)
? Hc for C2H5OH(l) = ?326700 cal
?Hc for CH3COOH(l) = ?208340 cal
?Hc for C2H5OOCCH3(l) = ?538760 cal
? Hf for H2O(l) = ?68317 cal