The gas phase mass transfer coefficient for the evaporation of a drop of ethyl alcohol in a stream of air

at $300$K and $1\mathrm{.}2$ bar pressure is kG$=2\mathrm{.}4$x$106$ kmol$/$s$.$m$2$

$.$mmHg$.$

a$)$ Calculate the values of the mass transfer coefficient if the deriving force is expressed in terms of

difference in $($i$)$ mole fraction of alcohol in the gas phase and $($ii$)$ mole concentration of alcohol

in kmol$/$m$3$

$($iii$)$ mole concentration of alcohol in kmol$/$m$3$

for equimolar counter diffusion.

b$)$ Calculate the FG

c$)$ If the diffusivity of alcohol in air is $0\mathrm{.}103$ cm$2$

$/$s at $300$K$,$ estimate the thickness of the stagnant

gas file.

Vapor pressure of alcohol $=0\mathrm{.}0877$ bar at $300$K