A liquid stream containing $50\mathrm{.}0$mole$\%$ benzene and the balance toluene at $25C$ is fed

to a continuous single$-$stage evaporator at a rate of $1320mo\frac{l}{s}.$ The liquid and vapor streams leaving

the evaporator are both at $65C.$ The liquid contains $42\mathrm{.}5$mole$\%$ benzene and the vapor contains $73\mathrm{.}5$

mole $\%$ benzene. Calculate the heating requirement for this process in $kW.$