Question 1 The gas phase of CO2 (A) – air system is in equilibrium with a water solution at 303K. XA for CO2 in equilibrium in the solution is 7.07 x 10-5 mole fraction. Given, Henry’s law constant = 0.186 x 104 atm/mole fraction, what is the partial pressure of CO2 in equilibrium (PA*)? Solution Solution: Question 2 In a wetted-wall tower an air-H2S mixture is flowing by a film of water that is flowing as a thin film down a vertical plate. The H2S is being absorbed from the air to the water at a total pressure of 1.50 atm abs and 30oC. A value for k’C of 9.567 x 10-4 m/s has been predicted for the gas phase mass transfer coefficient. At a given point the mole fraction of H2S in the liquid at the liquid-gas interface is 2.0 x 10-5 and pA of H2S in the gas is 0.05 atm. The Henry’s law equilibrium relation is pA (atm) = 609 xA (mole fraction in liquid). Calculate the rate of absorption of H2S. Solution:

Question 3 An impurity is being absorbed from air into water under extremely dilute conditions. Operating and equilibrium information for the system is given below. Use this information to calculate the following: a) The values of k’L, k’G, K’G b) The molar flux through the interface at a point in the equipment where the mole fraction of impurity in both bulk phases is 0.020 c) The controlling resistance to mass transfer d) The interface compositions in the two phases e) Sketch the mole fraction profiles near the interface in the two phases Date: Temperature 300K, PT = 100 kPa Henry’s law constant at 300K = 0.040 kPa/mol frac Liquid properties are those of water Film mass transfer coefficients: k’y 2.50 x 10-2 kmol/m2.s; k’x 1.11 x 10-2 kmol/m2.s Solution: