In an absorption column, the prevailing mass transfer coefficient for the gas film, kG, is 5107molm2Pa1s1 and that for the liquid film, kL, is 2104ms1. The interfacial equilibrium is governed by Henry's law with the constant, m=5. The prevailing pressure is 0.2MPa and the total liquid concentration, CT is 50kmolm3. (a) Show that when the above mass transfer coefficients are expressed in the same units as that of molar flux, i.e. ky and kx, the following equations apply: kY=PkGandkX=CTkL [2 marks] (b) Show that the overall mass transfer coefficient based on the overall driving force on the gas side, KY, is given by: KY1=kY1+kXm and that the overall mass transfer coefficient based on the overall driving force on the liquid side, Kx, is given by: KX=mKY [4 marks] (c) Calculate Ky and Kx and state which mass transfer film is controlling the transfer across the interface. [3 marks] (d) In the above absorption column a gas mixture containing 2% solute on volumetric basis at 298K is scrubbed with pure water. The gas flow rate is 900kgh1m2. If 98% of the solute is removed from the gas stream, calculate the minimum water rate in kgh1m2, i.e. for the case where the liquid flowing out of the column is fully saturated. Take the relative molecular mass of the gas mixture as 30gmol1 and of water as 18gmol1. [4 marks] List without any derivations all the underlying assumptions involved in the derivation of the design equation below for the calculation of the required packed column height, Z, for the absorption of a low concentration solute from a gas stream. Here, Gm is the molar flux of gas, Ky is the overall mass-transfer coefficient based on gas phase, a is the specific surface area of the packing per unit volume, yAB,yAT are the mol fraction of the solute in the gas stream at the bottom and the top of the packed column, respectively, and yAB,yAT are the driving forces, or the differences between the mol faction of the solute in the gas stream and that in equilibrium with the liquid, at the bottom and the top of the packed column, respectively. [3 marks]