In the extraction of acetic acid from an aqueous solution in benzene in a packed column of height $1\mathrm{.}4m$ and cross$-$sectional area $0\mathrm{.}0045m^2,$ the concentrations measured at the inlet and outlet of the column are:

acid concentration in the inlet water phase, $C_{w2}=0\mathrm{.}69$kmo$\frac{l}{m^3}$

acid concentration in the outlet water phase, $C_{w1}=0\mathrm{.}685$kmo$\frac{l}{m^3}$

lowrate of benzene phase $=5\mathrm{.}7{10}^{-6}\frac{m^3}{s}=1\mathrm{.}27{10}^{-3}\frac{m^3}{m^2}.s$

inlet benzene phase concentration, $C_{B1}=0\mathrm{.}0040$kmo$\frac{l}{m^3}$

outlet benzene phase concentration, $C_{B2}=0\mathrm{.}0115$kmo$\frac{l}{m^3}$

The equilibrium relationship for this system is:

$\frac{C_B^{**}}{C_w^{**}}=0\mathrm{.}0247$

Determine the overall transfer coefficient and the height of the transfer unit.