A gas phase, $V,$ containing $0\mathrm{.}4$ mole percent $($not mole fraction$)$ solute $A$ is to be purified

by countercurrently flowing pure liquid phase, $L,$ such that the exit gas stream contains

$0\mathrm{.}05$ mole percent A$.$ The Henry's law constant is $0\mathrm{.}776.$

a$)$ Discuss which phase controls the mass transfer. $($gas phase$)$

b$)$ Determine the composition of the exiting solvent stream, if the solvent flow rate is $1\mathrm{.}5$

times the minimum solvent flow rate, in a packed column. $(x_1=0\mathrm{.}00343)$

c$)$ Determine the number of transfer units based on the overall gas phase driving force, for

the packed column. $(N_{OG}=4\mathrm{.}1)$

d$)$ Determine the number of theoretical stages required to achieve the same separation

with the same operating conditions, in a plate tower. $(4)$

e$)$ Determine the composition of the exiting liquid stream and the solvent flow rate

$($relative to solvent flow rate in a plate tower$)$ that is required to achieve the same

separation in a single stage operation. $(x_l=0\mathrm{.}00064)$